Version July 2025
Note: Qsymia is a fixed-dose combination product of phentermine/topiramate formulated in a 3.75 mg phentermine/23 mg topiramate ratio.
Weight management, chronic:
Note: For use as adjunct therapy with a reduced-calorie diet and increased physical activity in pediatric patients; only use in patients 12 to <18 years of age with an initial BMI in the 95th percentile or higher for age and sex or patients ≥18 years who have a BMI ≥30 kg/m2 or patients with a BMI ≥27 kg/m2 and ≥1 weight-associated comorbidity (eg, dyslipidemia). Pregnancy status must be assessed monthly during therapy. Doses should be administered in the morning to prevent insomnia, which may occur if doses are administered in the evening. Therapeutic monitoring parameters for dosage adjustments vary by age; in patients 12 to <18 years of age, the rate of weight loss and BMI should be used and in patients ≥18 years of age, weight should be used.
Children ≥12 years and Adolescents <18 years: Qsymia:
Initial: Oral: 3.75 mg phentermine/23 mg topiramate once daily for 14 days, then increase to 7.5 mg phentermine/46 mg topiramate once daily; assess BMI after 12 weeks of therapy and adjust dose as appropriate.
Dosage adjustment: Oral:
• If during any point in therapy weight loss is >0.9 kg/week, consider a decrease in current dose.
• After the first 12 weeks of therapy at the 7.5 mg phentermine/46 mg topiramate daily dose, assess BMI.
- If BMI reduced by ≥3% from baseline, continue current dose of 7.5 mg phentermine/46 mg topiramate once daily.
- If BMI reduced by <3% from baseline after 12 weeks of therapy, increase dose to 11.25 mg phentermine/69 mg topiramate once daily for 14 days, then increase to 15 mg phentermine/92 mg topiramate once daily. After 12 weeks at highest dose, reassess patient's BMI. If BMI reduced by ≥5% from baseline, continue current dose. If BMI only reduced by <5%, discontinue therapy, as patient is unlikely to see further efficacy.
Adolescents ≥18 years of age: Qsymia:
Initial: Oral: 3.75 mg phentermine/23 mg topiramate once daily for 14 days, then increase to 7.5 mg phentermine/46 mg topiramate once daily; assess weight after 12 weeks of therapy and adjust dose as appropriate.
Dosage adjustment: Oral:
• After the first 12 weeks of therapy at the 7.5 mg phentermine/46 mg topiramate daily dose, assess weight.
- If weight reduced by ≥3% from baseline, continue current dose of 7.5 mg phentermine/46 mg topiramate once daily.
- If weight reduced by <3% from baseline after 12 weeks of therapy, increase dose to 11.25 mg phentermine/69 mg topiramate once daily for 14 days, then increase to 15 mg phentermine/92 mg topiramate once daily. After 12 weeks at highest dose, reassess patient's weight. If weight reduced by ≥5% from baseline, continue current dose. If weight only reduced by <5%, discontinue therapy, as patient is unlikely to see further efficacy.
Discontinuation of therapy: Children and Adolescents: Qsymia: Oral: Doses should be gradually tapered to prevent possibility of seizure activity; for example, patients on the 15 mg phentermine/92 mg topiramate daily dose should taper to every other day for 1 week prior to discontinuation.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Children ≥12 years and Adolescents: Oral:
Note: Kidney function may be estimated using the Cockcroft-Gault formula with actual body weight for dosage adjustment purposes.
CrCl ≥50 mL/minute: No dosage adjustment necessary.
CrCl <50 mL/minute: Maximum daily dose: 7.5 mg phentermine/46 mg topiramate once daily.
End-stage kidney disease on dialysis: Avoid use (has not been studied).
Children ≥12 years and Adolescents: Oral:
Mild impairment: No dosage adjustment necessary.
Moderate impairment: Maximum daily dose: 7.5 mg phentermine/46 mg topiramate once daily.
Severe impairment: Avoid use (has not been studied).
(For additional information see "Phentermine and topiramate: Drug information")
Dosage guidance:
Clinical considerations: Avoid in patients with heart disease or poorly controlled hypertension (Ref). In females of childbearing potential, perform pregnancy test prior to initiation and monthly thereafter. Phentermine/topiramate is a combination product formulated in a 3.75:23 ratio. Adult dosage recommendations expressed as total mg of phentermine/topiramate.
Weight management, chronic (alternative agent):
Note: For use in combination with diet and exercise in patients who cannot take preferred agents and who have a BMI ≥30 kg/m2 or patients with a BMI ≥27 kg/m2 and ≥1 weight-associated comorbidity (eg, dyslipidemia, type 2 diabetes, hypertension) (Ref).
Oral: Initial: Phentermine 3.75 mg/topiramate 23 mg once daily for 14 days. Increase dose as tolerated to phentermine 7.5 mg/topiramate 46 mg once daily for 12 weeks, then evaluate weight loss. If ≥3% of baseline body weight has not been lost, either discontinue therapy with a gradual taper (eg, switch from daily dosing to every other day dosing for at least 1 week before discontinuing) or escalate the dose based on tolerability and patient preference. Dose may be escalated to phentermine 11.25 mg/topiramate 69 mg once daily for 14 days, and then to a maximum dose of phentermine 15 mg/topiramate 92 mg once daily. Evaluate weight loss after 12 weeks on phentermine 15 mg/topiramate 92 mg; if ≥5% of baseline body weight has not been lost, discontinue therapy with a gradual taper (ie, switch from daily dosing to every-other-day dosing for at least 1 week before discontinuing) (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Manufacturer's labeling: Note: Kidney function may be estimated using the Cockcroft-Gault formula with actual body weight for dosage adjustment purposes.
CrCl ≥50 mL/minute: No dosage adjustment necessary.
CrCl <50 mL/minute: Maximum dose: Phentermine 7.5 mg/topiramate 46 mg once daily.
End-stage kidney disease on dialysis: Avoid use (has not been studied).
Alternate dosing (Ref):
CrCl ≥50 mL/minute: No dosage adjustment necessary.
CrCl 30 to 49 mL/minute: Maximum dose: Phentermine 7.5 mg/topiramate 46 mg once daily.
CrCl <30 mL/minute: Use is not recommended.
Mild impairment (Child-Pugh class A): No dosage adjustment necessary.
Moderate impairment (Child-Pugh class B): Maximum dose: Phentermine 7.5 mg/topiramate 46 mg once daily
Severe impairment (Child-Pugh class C): Avoid use (has not been studied).
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Adverse reactions reported in adults unless otherwise specified. Also see individual agents.
>10%:
Cardiovascular: Increased heart rate (adolescents, adults: >5 bpm: 70% to 81%; >10 bpm: 50% to 65%; >15 bpm: 33% to 43%; >20 bpm: 14% to 24%)
Endocrine & metabolic: Decreased serum bicarbonate (adolescents: 60% to 70%; adults: 6% to 13%)
Gastrointestinal: Constipation (8% to 16%), xerostomia (7% to 19%)
Nervous system: Headache (10% to 11%), paresthesia (adolescents: 2% to 3%; adults: 4% to 20%), sleep disturbance (6% to 11%; including insomnia)
Neuromuscular & skeletal: Decreased bone mineral density (adolescents)
Renal: Increased serum creatinine (≥0.3 mg/dL: [adolescents: 17%, adults: 7% to 8%]; ≥50% over baseline: [adults: 2% to 3%])
Respiratory: Nasopharyngitis (9% to 13%), upper respiratory tract infection (14% to 16%)
1% to 10%:
Cardiovascular: Chest discomfort (1% to 2%), palpitations (2%)
Dermatologic: Alopecia (2% to 4%), skin rash (3%)
Endocrine & metabolic: Decreased serum potassium (<3.5 mEq/L: 4% to 5%; <3 mEq/L: <1%), hypokalemia (1% to 3%), increased thirst (2%)
Gastrointestinal: Decreased appetite (2%), diarrhea (6%), dysgeusia (metallic taste: 7% to 9%), dyspepsia (3%), gastroenteritis (3%), gastroesophageal reflux disease (3%), nausea (6% to 7%), oral paresthesia (1% to 2%), upper abdominal pain (adolescents: 3%)
Genitourinary: Dysmenorrhea (1% to 2%), urinary tract infection (5%)
Infection: Influenza (adolescents, adults: 2% to 8%)
Nervous system: Anxiety (adolescents, adults: 2% to 8%), cognitive dysfunction (including problems with concentration, memory, and language [word finding]: 5% to 8%), depression (adolescents, adults: 2% to 8%), disturbance in attention (2% to 4%), dizziness (adolescents, adults: 2% to 9%), fatigue (adolescents, adults: 3% to 6%), hypoesthesia (4%), irritability (2% to 4%)
Neuromuscular & skeletal: Arthralgia (adolescents: 2% to 4%), back pain (6% to 7%), muscle spasm (3%), musculoskeletal chest pain (adolescents: 3%), musculoskeletal pain (2% to 3%), neck pain (2%)
Ophthalmic: Blurred vision (5% to 6%), dry eye syndrome (3%), eye pain (2%)
Renal: Nephrolithiasis (1%)
Respiratory: Bronchitis (5% to 7%), cough (5%), nasal congestion (2%), paranasal sinus congestion (3%), pharyngolaryngeal pain (3%), sinusitis (7% to 8%)
Miscellaneous: Fever (adolescents: 4%)
<1%: Nervous system: Suicidal ideation (adolescents), suicidal tendencies (adolescents)
Frequency not defined: Neuromuscular & skeletal: Linear skeletal growth rate below expectation (adolescents: reduction in height velocity)
Postmarketing:
Endocrine & metabolic: Hyperchloremic metabolic acidosis (nonanion gap)
Ophthalmic: Acute angle-closure glaucoma, increased intraocular pressure
Hypersensitivity to phentermine, topiramate, or any component of the formulation or idiosyncrasy to sympathomimetic amines; hyperthyroidism; glaucoma; use during or within 14 days following monoamine oxidase inhibitor therapy; pregnancy.
Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Concerns related to adverse effects:
• CNS effects: Cognitive dysfunction and psychiatric disturbances (mood disorders including anxiety, depression or insomnia) may occur with use; incidence of cognitive events (including attention, language, or memory difficulties) may be related to rapid titration and higher doses; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving). Risk may be increased in patients with a history of depression; dose reduction or discontinuation may be necessary.
• Dermatologic effects: Severe dermatologic reactions, including toxic epidermal necrolysis and Stevens-Johnson syndrome, have been reported with topiramate therapy; discontinue therapy if signs and symptoms occur.
• Hyperthermia: Topiramate may be associated (rarely) with severe oligohidrosis and hyperthermia; use caution and monitor closely during strenuous exercise, during exposure to high environmental temperature, or in patients receiving other carbonic anhydrase inhibitors and drugs with anticholinergic activity.
• Hypokalemia: Can cause hypokalemia; use caution with concurrent use of hydrochlorothiazide or furosemide as risk of hypokalemia may be increased; monitor potassium closely.
• Metabolic acidosis (hyperchloremic, nonanion gap): May decrease serum bicarbonate concentrations, due to inhibition of carbonic anhydrase and increased renal bicarbonate loss. Risk may be increased in patients with conditions that predispose to acidosis (eg, diarrhea, ketogenic diet, renal disease, severe respiratory disorders, status epilepticus, surgery) or concurrent treatment with other carbonic anhydrase inhibitors. Monitor serum electrolytes and bicarbonate prior to and during treatment. Reduce dose or discontinue use if persistent metabolic acidosis develops.
• Ocular effects: Topiramate has been associated with acute myopia and secondary angle-closure glaucoma in adults and children, typically within 1 month of initiation but may occur at any time; discontinue in patients with acute onset of decreased visual acuity or ocular pain. Topiramate is also associated with visual field effects, which may occur without elevation of intraocular pressure; most effects were reversible with discontinuation.
• Renal calculus: Use is associated with kidney stone formation. Topiramate exhibits weak carbonic anhydrase inhibitory properties and may increase the risk of kidney stones. The risk of stones may be increased in patients on a ketogenic diet or concurrent treatment with other carbonic anhydrase inhibitors; risk of stones may be reduced by increasing fluid intake.
• Renal effects: May increase serum creatinine; peak increases from baseline were observed after 4 to 8 weeks of treatment. Changes in serum creatinine (and GFR) with short-term use appear reversible with discontinuation; effects of long-term treatment on renal function are not known. Monitor serum creatinine prior to and during treatment. For persistent elevations, dose reduction or discontinuation may be necessary.
• Suicidal ideation: Pooled analysis of trials involving various antiseizure medications (regardless of indication) showed an increased risk of suicidal thoughts/behavior (incidence rate: 0.43% treated patients compared to 0.24% of patients receiving placebo); risk observed as early as 1 week after initiation and continued through duration of trials (most trials ≤24 weeks). Avoid use in patients with history of suicide attempts or current suicidal ideation. Monitor all patients for notable changes in depression, suicidal thoughts or behavior; discontinue use in patients who experience suicidal thoughts or behavior.
Disease-related concerns:
• Hepatic impairment: Use with caution in patients with hepatic impairment; dosage adjustment may be required. Avoid use in patients with severe hepatic impairment (Child-Pugh class C).
• Renal impairment: Use with caution in patients with renal impairment; dosage adjustment may be required. Avoid use in patients with end-stage renal disease on dialysis.
Dosage form specific issues:
• Tartrazine: May contain FD&C Yellow No. 5 (tartrazine), which may cause allergic reactions, including bronchial asthma in susceptible individuals, especially in patients with aspirin hypersensitivity.
Other warnings/precautions:
• Abuse potential: Phentermine is pharmacologically related to the amphetamines, which have a high abuse potential; prolonged use may lead to dependency. Prescriptions should be written for the smallest quantity consistent with good patient care to minimize the possibility of overdose.
• Withdrawal: Antiseizure medications (including topiramate) should not be discontinued abruptly because of the possibility of increasing seizure frequency. Therapy should be withdrawn gradually to minimize the potential of increased seizure frequency, unless safety concerns require a more rapid withdrawal.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Capsule, extended release, oral:
Qsymia: 3.75/23: Phentermine 3.75 mg [immediate release] and topiramate 23 mg [extended release] [contains tartrazine]
Qsymia: 7.5/46: Phentermine 7.5 mg [immediate release] and topiramate 46 mg [extended release] [contains tartrazine]
Qsymia: 11.25/69: Phentermine 11.25 mg [immediate release] and topiramate 69 mg [extended release] [contains tartrazine]
Qsymia: 15/92: Phentermine 15 mg [immediate release] and topiramate 92 mg [extended release] [contains tartrazine]
Capsule ER 24 Hour Therapy Pack (Qsymia Oral)
3.75-23 mg (per each): $8.09
7.5-46 mg (per each): $8.36
11.25-69 mg (per each): $8.97
15-92 mg (per each): $8.97
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
C-IV
Oral: Administer in the morning without regard to food; avoid late evening administration (potential for insomnia).
Oral: Administer in the morning without regard to meals; avoid late evening administration (potential for insomnia).
Bariatric surgery: Capsule, extended release: Some institutions may have specific protocols that conflict with these recommendations; refer to institutional protocols as appropriate. ER capsule should be swallowed whole. Do not open, crush, chew, or divide. No alternative formulations are available. Individual components of phentermine and topiramate are available as IR tablets. If safety and efficacy can be effectively monitored, no change in formulation or administration is required after bariatric surgery; however, careful evaluation of GI status (gastric emptying and small bowel transit), nutritional intake, and behavioral habits is strongly advised before administering anorexiant agents after bariatric surgery.
Topiramate is a hazardous agent (NIOSH 2024 [table 2]).
Use appropriate precautions for receiving, handling, storage, preparation, dispensing, transporting, administration, and disposal. Follow NIOSH and USP 800 recommendations and institution-specific policies/procedures for appropriate containment strategy (NIOSH 2023; NIOSH 2024; USP-NF 2020).
Note: Facilities may perform risk assessment of some hazardous drugs to determine if appropriate for alternative handling and containment strategies (USP-NF 2020). Refer to institution-specific handling policies/procedures.
Store at 20°C to 25°C (68°F to 77°F); excursions permitted between 15°C to 30°C (59°F to 86°F).
An FDA-approved patient medication guide, which is available with the product information and at https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/022580s025lbl.pdf#page=43, must be dispensed with this medication.
Adjunct treatment for chronic weight management along with a reduced-calorie diet and increased physical activity in pediatric patients with an initial BMI in the ≥95th percentile standardized for age and sex (FDA approved in pediatric patients ≥12 years of age); adjunct treatment for chronic weight management along with a reduced-calorie diet and increased physical activity in patients with either an initial BMI of ≥30 kg/m2 or an initial BMI of ≥27 kg/m2 and at least one weight-related comorbid condition (eg, dyslipidemia, type 2 diabetes, hypertension) (FDA approved in adults).
The Institute for Safe Medication Practices (ISMP) includes this medication among its list of drugs (contraindicated in pregnancy) which have a heightened risk of causing significant patient harm when used in error (High-Alert Medications in Community/Ambulatory Care Settings).
Refer to individual components.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program
Acebrophylline: May increase stimulatory effects of CNS Stimulants. Risk X: Avoid
Acrivastine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Agents with Clinically Relevant Anticholinergic Effects: May increase adverse/toxic effects of Topiramate. Risk C: Monitor
Alcohol (Ethyl): May increase CNS depressant effects of Topiramate. Alcohol (Ethyl) may increase serum concentration of Topiramate. This applies specifically to use with one extended-release topiramate product (Trokendi XR). Also, topiramate concentrations may be subtherapeutic in the later portion of the dosage interval. Management: Concurrent use of alcohol within 6 hours of ingestion of extended-release topiramate (Trokendi XR) is contraindicated. Any use of alcohol with other topiramate products should be avoided when possible and should only be undertaken with extreme caution. Risk X: Avoid
Alizapride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Alkalinizing Agents: May decrease excretion of Amphetamines. Management: Consider alternatives to using amphetamines and alkalinizing agents in combination. If these agents must be used together, patients should be monitored closely for excessive amphetamine effects. Risk D: Consider Therapy Modification
Amantadine: Carbonic Anhydrase Inhibitors may increase serum concentration of Amantadine. Risk C: Monitor
Amifampridine: Agents With Seizure Threshold Lowering Potential may increase neuroexcitatory and/or seizure-potentiating effects of Amifampridine. Risk C: Monitor
Amisulpride (Oral): Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Amisulpride (Oral). Specifically, the risk of seizures may be increased. Risk C: Monitor
Amisulpride (Oral): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Amitriptyline: Topiramate may increase CNS depressant effects of Amitriptyline. Topiramate may increase serum concentration of Amitriptyline. Topiramate may increase active metabolite exposure of Amitriptyline. Risk C: Monitor
Ammonium Chloride: May decrease serum concentration of Amphetamines. This effect is likely due to an enhanced excretion of amphetamines in the urine. Risk C: Monitor
Antihypertensive Agents: Amphetamines may decrease antihypertensive effects of Antihypertensive Agents. Risk C: Monitor
Antipsychotic Agents: May decrease stimulatory effects of Amphetamines. Antipsychotic Agents may increase adverse/toxic effects of Amphetamines. Risk C: Monitor
ARIPiprazole Lauroxil: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of ARIPiprazole Lauroxil. Specifically, the risk of seizures may be increased. Risk C: Monitor
ARIPiprazole: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of ARIPiprazole. Specifically, the risk of seizures may be increased. Risk C: Monitor
Articaine: May increase CNS depressant effects of CNS Depressants. Management: Consider reducing the dose of articaine if possible when used in patients who are also receiving CNS depressants. Monitor for excessive CNS depressant effects with any combined use. Risk D: Consider Therapy Modification
Asenapine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Asenapine. Specifically, the risk of seizures may be increased. Risk C: Monitor
Atomoxetine: May increase hypertensive effects of Sympathomimetics. Atomoxetine may increase tachycardic effects of Sympathomimetics. Risk C: Monitor
Azelastine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Benperidol: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Benperidol. Specifically, the risk of seizures may be increased. Risk C: Monitor
Benperidol: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Blonanserin: CNS Depressants may increase CNS depressant effects of Blonanserin. Management: Use caution if coadministering blonanserin and CNS depressants; dose reduction of the other CNS depressant may be required. Strong CNS depressants should not be coadministered with blonanserin. Risk D: Consider Therapy Modification
Bornaprine: Sympathomimetics may increase anticholinergic effects of Bornaprine. Risk C: Monitor
Brexanolone: CNS Depressants may increase CNS depressant effects of Brexanolone. Risk C: Monitor
Brexpiprazole: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Brexpiprazole. Specifically, the risk of seizures may be increased. Risk C: Monitor
Brimonidine (Topical): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Bromopride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Bromperidol: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Buclizine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Buprenorphine: CNS Depressants may increase CNS depressant effects of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. Risk D: Consider Therapy Modification
BuPROPion: May increase neuroexcitatory and/or seizure-potentiating effects of Agents With Seizure Threshold Lowering Potential. Risk C: Monitor
BusPIRone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Cannabinoid-Containing Products: CNS Depressants may increase CNS depressant effects of Cannabinoid-Containing Products. Risk C: Monitor
Cannabinoid-Containing Products: May increase tachycardic effects of Sympathomimetics. Risk C: Monitor
CarBAMazepine: Topiramate may increase CNS depressant effects of CarBAMazepine. CarBAMazepine may decrease serum concentration of Topiramate. Risk C: Monitor
Carbonic Anhydrase Inhibitors: May increase adverse/toxic effects of Carbonic Anhydrase Inhibitors. The development of acid-base disorders with concurrent use of ophthalmic and oral carbonic anhydrase inhibitors has been reported. Management: Avoid concurrent use of different carbonic anhydrase inhibitors if possible. Monitor patients closely for the occurrence of kidney stones and with regards to severity of metabolic acidosis. Risk X: Avoid
Cariprazine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Cariprazine. Specifically, the risk of seizures may be increased. Risk C: Monitor
Cetirizine (Systemic): May increase CNS depressant effects of CNS Depressants. Management: Consider avoiding this combination if possible. If required, monitor for excessive sedation or CNS depression, limit the dose and duration of combination therapy, and consider CNS depressant dose reductions. Risk D: Consider Therapy Modification
Chloral Hydrate/Chloral Betaine: CNS Depressants may increase CNS depressant effects of Chloral Hydrate/Chloral Betaine. Management: Consider alternatives to the use of chloral hydrate or chloral betaine and additional CNS depressants. If combined, consider a dose reduction of either agent and monitor closely for enhanced CNS depressive effects. Risk D: Consider Therapy Modification
Chlormethiazole: May increase CNS depressant effects of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Risk D: Consider Therapy Modification
Chlorphenesin Carbamate: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor
ChlorproMAZINE: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of ChlorproMAZINE. Specifically, the risk of seizures may be increased. Risk C: Monitor
Clothiapine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Clothiapine. Specifically, the risk of seizures may be increased. Risk C: Monitor
CloZAPine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of CloZAPine. Specifically, the risk of seizures may be increased. Risk C: Monitor
CNS Depressants: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor
Cocaine (Topical): May increase hypertensive effects of Sympathomimetics. Management: Consider alternatives to use of this combination when possible. Monitor closely for substantially increased blood pressure or heart rate and for any evidence of myocardial ischemia with concurrent use. Risk D: Consider Therapy Modification
Dantrolene: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Daridorexant: May increase CNS depressant effects of CNS Depressants. Management: Dose reduction of daridorexant and/or any other CNS depressant may be necessary. Use of daridorexant with alcohol is not recommended, and the use of daridorexant with any other drug to treat insomnia is not recommended. Risk D: Consider Therapy Modification
Desmopressin: Hyponatremia-Associated Agents may increase hyponatremic effects of Desmopressin. Risk C: Monitor
DexmedeTOMIDine: CNS Depressants may increase CNS depressant effects of DexmedeTOMIDine. Management: Monitor for increased CNS depression during coadministration of dexmedetomidine and CNS depressants, and consider dose reductions of either agent to avoid excessive CNS depression. Risk D: Consider Therapy Modification
Difelikefalin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Difenoxin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Dihydralazine: CNS Depressants may increase hypotensive effects of Dihydralazine. Risk C: Monitor
Dihydralazine: Sympathomimetics may decrease therapeutic effects of Dihydralazine. Risk C: Monitor
Dimethindene (Topical): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Dothiepin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Doxofylline: Sympathomimetics may increase adverse/toxic effects of Doxofylline. Risk C: Monitor
Doxylamine: CNS Depressants may increase CNS depressant effects of Doxylamine. Risk C: Monitor
DroPERidol: May increase CNS depressant effects of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Risk D: Consider Therapy Modification
Emedastine (Systemic): May increase CNS depressant effects of CNS Depressants. Management: Consider avoiding this combination if possible. If required, monitor for excessive sedation or CNS depression, limit the dose and duration of combination therapy, and consider CNS depressant dose reductions. Risk C: Monitor
Entacapone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Esketamine (Injection): May increase adverse/toxic effects of Sympathomimetics. Specifically, the risk for elevated heart rate, hypertension, and arrhythmias may be increased. Risk C: Monitor
Esketamine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Esketamine (Nasal): May increase hypertensive effects of CNS Stimulants. Risk C: Monitor
Flecainide: Carbonic Anhydrase Inhibitors may decrease excretion of Flecainide. Risk C: Monitor
Flunarizine: CNS Depressants may increase CNS depressant effects of Flunarizine. Risk X: Avoid
Flunitrazepam: CNS Depressants may increase CNS depressant effects of Flunitrazepam. Management: Reduce the dose of CNS depressants when combined with flunitrazepam and monitor patients for evidence of CNS depression (eg, sedation, respiratory depression). Use non-CNS depressant alternatives when available. Risk D: Consider Therapy Modification
Fluorodopa F18: Coadministration of CNS Stimulants and Fluorodopa F18 may alter diagnostic results. Management: Discontinue medications used to treat Parkinson disease, including dopamine reuptake inhibitors and dopamine releasing agents, such as psychostimulants, 12 hours prior to fluorodopa F 18 administration if these medications can be safely withheld. Risk D: Consider Therapy Modification
Flupentixol: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Flupentixol. Specifically, the risk of seizures may be increased. Risk C: Monitor
FluPHENAZine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of FluPHENAZine. Specifically, the risk of seizures may be increased. Risk C: Monitor
Fosphenytoin-Phenytoin: May decrease serum concentration of Topiramate. Topiramate may increase serum concentration of Fosphenytoin-Phenytoin. Risk C: Monitor
Gastrointestinal Acidifying Agents: May decrease serum concentration of Amphetamines. Risk C: Monitor
Guanethidine: May increase hypertensive effects of Sympathomimetics. Guanethidine may increase arrhythmogenic effects of Sympathomimetics. Risk C: Monitor
Haloperidol: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Haloperidol. Specifically, the risk of seizures may be increased. Risk C: Monitor
Hormonal Contraceptives: Topiramate may decrease serum concentration of Hormonal Contraceptives. Management: Advise patients to use an alternative method of contraception or a back-up method during coadministration, and to continue back-up contraception for 28 days after discontinuing topiramate to ensure contraceptive reliability. Risk D: Consider Therapy Modification
HydrOXYzine: May increase CNS depressant effects of CNS Depressants. Management: Consider a decrease in the CNS depressant dose, as appropriate, when used together with hydroxyzine. Increase monitoring of signs/symptoms of CNS depression in any patient receiving hydroxyzine together with another CNS depressant. Risk D: Consider Therapy Modification
Iloperidone: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Iloperidone. Specifically, the risk of seizures may be increased. Risk C: Monitor
Inhalational Anesthetics: Amphetamines may increase hypotensive effects of Inhalational Anesthetics. Risk C: Monitor
Inhibitors of the Proton Pump (PPIs and PCABs): May increase absorption of Amphetamines. Specifically, the amphetamine absorption rate may be increased in the first hours after dosing. Risk C: Monitor
Iobenguane Radiopharmaceutical Products: Amphetamines may decrease therapeutic effects of Iobenguane Radiopharmaceutical Products. Management: Discontinue all drugs that may inhibit or interfere with catecholamine transport or uptake for at least 5 biological half-lives before iobenguane administration. Do not administer these drugs until at least 7 days after each iobenguane dose. Risk X: Avoid
Iobenguane Radiopharmaceutical Products: CNS Stimulants may decrease therapeutic effects of Iobenguane Radiopharmaceutical Products. Management: Discontinue all drugs that may inhibit or interfere with catecholamine transport or uptake for at least 5 biological half-lives before iobenguane administration. Do not administer these drugs until at least 7 days after each iobenguane dose. Risk X: Avoid
Ioflupane I 123: Coadministration of Phentermine and Ioflupane I 123 may alter diagnostic results. Risk C: Monitor
Iohexol: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Iohexol. Specifically, the risk for seizures may be increased. Management: Discontinue agents that may lower the seizure threshold 48 hours prior to intrathecal use of iohexol. Wait at least 24 hours after the procedure to resume such agents. In nonelective procedures, consider use of prophylactic antiseizure drugs. Risk D: Consider Therapy Modification
Iomeprol: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Iomeprol. Specifically, the risk for seizures may be increased. Management: Discontinue agents that may lower the seizure threshold 48 hours prior to intrathecal use of iomeprol. Wait at least 24 hours after the procedure to resume such agents. In nonelective procedures, consider use of prophylactic antiseizure drugs. Risk D: Consider Therapy Modification
Iopamidol: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Iopamidol. Specifically, the risk for seizures may be increased. Management: Discontinue agents that may lower the seizure threshold 48 hours prior to intrathecal use of iopamidol. Wait at least 24 hours after the procedure to resume such agents. In nonelective procedures, consider use of prophylactic antiseizure drugs. Risk D: Consider Therapy Modification
Ixabepilone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Kava Kava: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Ketotifen (Systemic): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Kratom: May increase adverse/toxic effects of Sympathomimetics. Risk X: Avoid
Kratom: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Lacosamide: Antiseizure Agents (Sodium Channel Blockers) may increase adverse/toxic effects of Lacosamide. Specifically the risk for bradycardia, ventricular tachyarrhythmias, or a prolonged PR interval may be increased. Risk C: Monitor
LamoTRIgine: Topiramate may increase arrhythmogenic effects of LamoTRIgine. LamoTRIgine may increase CNS depressant effects of Topiramate. Management: Consider the risk of serious arrhythmias or death versus any expected benefit of lamotrigine in patients receiving concomitant sodium channel blockers. Additionally, if combined, caution patients that CNS depressant effects may be increased. Risk D: Consider Therapy Modification
Landiolol: Sympathomimetics may decrease therapeutic effects of Landiolol. Risk C: Monitor
Lemborexant: May increase CNS depressant effects of CNS Depressants. Management: Dosage adjustments of lemborexant and of concomitant CNS depressants may be necessary when administered together because of potentially additive CNS depressant effects. Close monitoring for CNS depressant effects is necessary. Risk D: Consider Therapy Modification
Levocetirizine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Levothyroxine: May increase therapeutic effects of Sympathomimetics. Sympathomimetics may increase therapeutic effects of Levothyroxine. Levothyroxine may increase adverse/toxic effects of Sympathomimetics. Specifically, the risk of coronary insufficiency may be increased in patients with coronary artery disease. Risk C: Monitor
Lisuride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Lithium: Topiramate may increase serum concentration of Lithium. Risk C: Monitor
Lofepramine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Lofexidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Loop Diuretics: May increase hypokalemic effects of Topiramate. Risk C: Monitor
Loxapine: CNS Depressants may increase CNS depressant effects of Loxapine. Management: Consider reducing the dose of CNS depressants administered concomitantly with loxapine due to an increased risk of respiratory depression, sedation, hypotension, and syncope. Risk D: Consider Therapy Modification
Lumateperone: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Lumateperone. Specifically, the risk of seizures may be increased. Risk C: Monitor
Lurasidone: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Lurasidone. Specifically, the risk of seizures may be increased. Risk C: Monitor
Magnesium Sulfate: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Mefloquine: May decrease therapeutic effects of Antiseizure Agents. Mefloquine may decrease serum concentration of Antiseizure Agents. Management: Mefloquine is contraindicated for malaria prophylaxis in persons with a history of seizures. If antiseizure drugs are being used for another indication, monitor antiseizure drug concentrations and treatment response closely with concurrent use. Risk D: Consider Therapy Modification
Melitracen [INT]: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Memantine: Carbonic Anhydrase Inhibitors may increase serum concentration of Memantine. Risk C: Monitor
Mequitazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Metergoline: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
MetFORMIN: Topiramate may increase adverse/toxic effects of MetFORMIN. Specifically, the risk for lactic acidosis may be increased. MetFORMIN may increase serum concentration of Topiramate. Topiramate may increase serum concentration of MetFORMIN. Risk C: Monitor
Methenamine: Carbonic Anhydrase Inhibitors may decrease therapeutic effects of Methenamine. Management: Consider avoiding the concomitant use of medications that alkalinize the urine, such as carbonic anhydrase inhibitors, and methenamine. Monitor for decreased therapeutic effects of methenamine if used concomitant with a carbonic anhydrase inhibitor. Risk D: Consider Therapy Modification
Methotrimeprazine: CNS Depressants may increase CNS depressant effects of Methotrimeprazine. Methotrimeprazine may increase CNS depressant effects of CNS Depressants. Management: Reduce the usual dose of CNS depressants by 50% if starting methotrimeprazine until the dose of methotrimeprazine is stable. Monitor patient closely for evidence of CNS depression. Risk D: Consider Therapy Modification
Methoxyflurane: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Metoclopramide: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
MetyraPONE: Coadministration of Antiseizure Agents and MetyraPONE may alter diagnostic results. Management: Consider alternatives to the use of the metyrapone test in patients taking antiseizure agents. Risk D: Consider Therapy Modification
MetyroSINE: CNS Depressants may increase sedative effects of MetyroSINE. Risk C: Monitor
Mianserin: May decrease therapeutic effects of Antiseizure Agents. Risk C: Monitor
Minocycline (Systemic): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Molindone: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Molindone. Specifically, the risk of seizures may be increased. Risk C: Monitor
Monoamine Oxidase Inhibitors: May increase hypertensive effects of Amphetamines. While linezolid and tedizolid may interact via this mechanism, management recommendations differ from other monoamine oxidase inhibitors. Refer to monographs specific to those agents for details. Risk X: Avoid
Moxonidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Multivitamins/Fluoride (with ADE): May decrease serum concentration of Amphetamines. More specifically, the ascorbic acid (vitamin C) in many multivitamins may decrease amphetamine concentrations. Risk C: Monitor
Multivitamins/Minerals (with ADEK, Folate, Iron): May decrease serum concentration of Amphetamines. Risk C: Monitor
Multivitamins/Minerals (with AE, No Iron): May decrease serum concentration of Amphetamines. Specifically, vitamin C may impair absorption of amphetamines. Risk C: Monitor
Nabilone: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Nalfurafine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Noscapine: CNS Depressants may increase adverse/toxic effects of Noscapine. Risk X: Avoid
OLANZapine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of OLANZapine. Specifically, the risk of seizures may be increased. Risk C: Monitor
Olopatadine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Opicapone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Opioid Agonists: CNS Depressants may increase CNS depressant effects of Opioid Agonists. Management: Avoid concomitant use of opioid agonists and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider Therapy Modification
Opipramol: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Orlistat: May decrease serum concentration of Antiseizure Agents. Risk C: Monitor
Orphenadrine: CNS Depressants may increase CNS depressant effects of Orphenadrine. Risk X: Avoid
Oxomemazine: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Oxybate Salt Products: CNS Depressants may increase CNS depressant effects of Oxybate Salt Products. Management: Consider alternatives to this combination when possible. If combined, dose reduction or discontinuation of one or more CNS depressants (including the oxybate salt product) should be considered. Interrupt oxybate salt treatment during short-term opioid use Risk D: Consider Therapy Modification
OxyCODONE: CNS Depressants may increase CNS depressant effects of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider Therapy Modification
Paliperidone: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Paliperidone. Specifically, the risk of seizures may be increased. Risk C: Monitor
Paliperidone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Paraldehyde: CNS Depressants may increase CNS depressant effects of Paraldehyde. Risk X: Avoid
Perampanel: Topiramate may increase CNS depressant effects of Perampanel. Topiramate may decrease serum concentration of Perampanel. Risk C: Monitor
Periciazine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Periciazine. Specifically, the risk of seizures may be increased. Risk C: Monitor
Periciazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Perphenazine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Perphenazine. Specifically, the risk of seizures may be increased. Risk C: Monitor
Pimozide: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Pimozide. Specifically, the risk of seizures may be increased. Risk C: Monitor
Pioglitazone: Topiramate may decrease serum concentration of Pioglitazone. Risk C: Monitor
Pipamperone: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Pipamperone. Specifically, the risk of seizures may be increased. Risk X: Avoid
Piribedil: CNS Depressants may increase CNS depressant effects of Piribedil. Risk C: Monitor
Pizotifen: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Polyethylene Glycol-Electrolyte Solution: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Polyethylene Glycol-Electrolyte Solution. Specifically, the risk of seizure may be increased. Risk C: Monitor
Pramipexole: CNS Depressants may increase sedative effects of Pramipexole. Risk C: Monitor
Procarbazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Prochlorperazine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Prochlorperazine. Specifically, the risk of seizures may be increased. Risk C: Monitor
Promazine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Promazine. Specifically, the risk of seizures may be increased. Risk C: Monitor
QUEtiapine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of QUEtiapine. Specifically, the risk of seizures may be increased. Risk C: Monitor
Quinolones: Amphetamines may increase cardiotoxic effects of Quinolones. Risk C: Monitor
Rilmenidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
RisperiDONE: May increase CNS depressant effects of Topiramate. Topiramate may decrease serum concentration of RisperiDONE. Risk C: Monitor
Ropeginterferon Alfa-2b: CNS Depressants may increase adverse/toxic effects of Ropeginterferon Alfa-2b. Specifically, the risk of neuropsychiatric adverse effects may be increased. Management: Avoid coadministration of ropeginterferon alfa-2b and other CNS depressants. If this combination cannot be avoided, monitor patients for neuropsychiatric adverse effects (eg, depression, suicidal ideation, aggression, mania). Risk D: Consider Therapy Modification
ROPINIRole: CNS Depressants may increase sedative effects of ROPINIRole. Risk C: Monitor
Rotigotine: CNS Depressants may increase sedative effects of Rotigotine. Risk C: Monitor
Salicylates: May increase adverse/toxic effects of Carbonic Anhydrase Inhibitors. Salicylate toxicity might be enhanced by this same combination. Management: Avoid these combinations when possible.Dichlorphenamide use with high-dose aspirin as contraindicated. If another combination is used, monitor patients closely for adverse effects. Tachypnea, anorexia, lethargy, and coma have been reported. Risk D: Consider Therapy Modification
Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors): Amphetamines may increase serotonergic effects of Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors). This could result in serotonin syndrome. Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors) may increase serum concentration of Amphetamines. Management: Monitor for amphetamine toxicities, including serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability). Initiate amphetamines at lower doses, monitor frequently, and adjust dose as needed. Risk C: Monitor
Serotonergic Agents (High Risk): Amphetamines may increase serotonergic effects of Serotonergic Agents (High Risk). This could result in serotonin syndrome. Management: Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability). Initiate amphetamines at lower doses, monitor frequently, and adjust doses as needed. Risk C: Monitor
Sertindole: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Sertindole. Specifically, the risk of seizures may be increased. Risk C: Monitor
Sodium Phosphates: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Sodium Phosphates. Specifically, the risk of seizure or loss of consciousness may be increased in patients with significant sodium phosphate-induced fluid or electrolyte abnormalities. Risk C: Monitor
Solriamfetol: CNS Stimulants may increase hypertensive effects of Solriamfetol. CNS Stimulants may increase tachycardic effects of Solriamfetol. Risk C: Monitor
Solriamfetol: Sympathomimetics may increase hypertensive effects of Solriamfetol. Sympathomimetics may increase tachycardic effects of Solriamfetol. Risk C: Monitor
Sulpiride: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Sulpiride. Specifically, the risk of seizures may be increased. Risk C: Monitor
Suvorexant: CNS Depressants may increase CNS depressant effects of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Risk D: Consider Therapy Modification
Sympathomimetics: May increase adverse/toxic effects of Sympathomimetics. Risk C: Monitor
Tedizolid: May increase adverse/toxic effects of Sympathomimetics. Specifically, the risk for increased blood pressure and heart rate may be increased. Risk C: Monitor
Thalidomide: CNS Depressants may increase CNS depressant effects of Thalidomide. Risk X: Avoid
Thiazide and Thiazide-Like Diuretics: May increase hypokalemic effects of Topiramate. Thiazide and Thiazide-Like Diuretics may increase serum concentration of Topiramate. Risk C: Monitor
Thioridazine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Thioridazine. Specifically, the risk of seizures may be increased. Risk C: Monitor
Thiothixene: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Thiothixene. Specifically, the risk of seizures may be increased. Risk C: Monitor
Trifluoperazine: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Trifluoperazine. Specifically, the risk of seizures may be increased. Risk C: Monitor
Trimeprazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Ulipristal: Topiramate may decrease serum concentration of Ulipristal. Risk X: Avoid
Urinary Acidifying Agents: May decrease serum concentration of Amphetamines. Risk C: Monitor
Valerian: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Valproic Acid and Derivatives: Topiramate may increase adverse/toxic effects of Valproic Acid and Derivatives. Specifically, the risk of hypothermia and hyperammonemia, with or without encephalopathy, may be increased. Valproic Acid and Derivatives may decrease serum concentration of Topiramate. Topiramate may decrease serum concentration of Valproic Acid and Derivatives. Risk C: Monitor
Ziprasidone: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Ziprasidone. Specifically, the risk of seizures may be increased. Risk C: Monitor
Zolpidem: CNS Depressants may increase CNS depressant effects of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Risk D: Consider Therapy Modification
Zuclopenthixol: Agents With Seizure Threshold Lowering Potential may increase adverse/toxic effects of Zuclopenthixol. Specifically, the risk of seizures may be increased. Risk C: Monitor
Zuranolone: May increase CNS depressant effects of CNS Depressants. Management: Consider alternatives to the use of zuranolone with other CNS depressants or alcohol. If combined, consider a zuranolone dose reduction and monitor patients closely for increased CNS depressant effects. Risk D: Consider Therapy Modification
Take in the morning; avoid taking in the late evening. Most effective when combined with a low calorie diet, increased physical activity and behavior modification counseling.
Evaluate pregnancy status prior to use in patients who can become pregnant. Patients who can become pregnant should have a negative pregnancy test prior to and monthly during therapy. Effective contraception should be used during treatment. Irregular bleeding may occur with use of combination oral contraceptives; efficacy of contraception may be dependent upon dose. Consult drug interactions database for more detailed information.
Obesity increases the risk of infertility. Optimal weight control prior to conception improves pregnancy outcomes. However, medications for weight loss are not recommended prior to pregnancy due to safety issues and adverse events. Weight loss medications should be discontinued prior to conception (ACOG 2021; Wharton 2020).
An increased risk in oral clefts (cleft lip with or without cleft palate) has been reported with first trimester exposure to topiramate. An increased risk of small for gestational age has also been reported following in utero exposure to topiramate.
An increased risk of adverse maternal and fetal events is associated with obesity. However, moderate gestational weight gain based on pre-pregnancy BMI is required for positive fetal outcomes in all pregnancies, including patients with overweight or obesity. Therefore, medications for weight loss therapy are not recommended during pregnancy (ACOG 2021; Wharton 2020). Use of this combination product is contraindicated during pregnancy. Refer to individual monographs for additional information.
Data collection to monitor pregnancy and infant outcomes following exposure is ongoing. Health care providers should report all pregnancies exposed to Qsymia in the Qsymia Pregnancy Surveillance Program (1-888-998-4887).
Pregnancy status (baseline, monthly with therapy; must be negative); weight, height, BMI; heart rate (resting); serum bicarbonate, potassium, glucose, and serum creatinine (at baseline and periodically); blood pressure; suicidality or mood disorders; symptoms of secondary angle-closure glaucoma; symptoms of acute acidosis and complications of long-term acidosis (eg, nephrolithiasis); dermatologic reactions.
Phentermine: A sympathomimetic amine with pharmacologic properties similar to amphetamines. The mechanism of action in reducing appetite appears to be secondary to CNS effects, including stimulation of the hypothalamus to release norepinephrine.
Topiramate: Effect on weight management may be due to its effects on appetite suppression and satiety enhancement and based on a combination of potential mechanisms: blocks neuronal voltage-dependent sodium channels, enhances GABA(A) activity, antagonizes AMPA/kainite glutamate receptors, and weakly inhibits carbonic anhydrase.
See individual agents.
