Version July 2025
Note: Dosage expressed in terms of elemental phosphorus.
Internal contamination with radioactive phosphorus (P-32) (off-label use): Oral: 250 to 500 mg 4 times daily (Ref).
Phosphate supplement: Oral: 250 to 500 mg 4 times daily.
Urinary acidification (K-Phos No. 2): Oral: 250 mg 4 times daily; may be increased to 250 mg every 2 hours when the urine is difficult to acidify (maximum: 2,000 mg/day).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustment provided in the manufacturer’s labeling. Use with caution. Contraindicated in patients with severe impairment (<30% of normal function).
There are no dosage adjustments provided in the manufacturer’s labeling. Use with caution.
Refer to adult dosing.
(For additional information see "Potassium phosphate and sodium phosphate: Pediatric drug information")
Note: Consider the contribution of sodium and potassium cations when determining appropriate phosphate replacement. Dosing is presented as mg/day and mmol/day; use extra caution. Note: 1 mmol phosphate = 31 mg phosphorus; 1 mg phosphorus = 0.032 mmol phosphate. Dosage expressed in terms of phosphate/phosphorus.
Dietary supplementation: K-Phos Neutral, Phospha 250 Neutral, Phos NaK, Phospho Trin 250 Neutral:
Children >4 years and Adolescents: Oral: 250 mg elemental phosphorus (1 tablet) 4 times daily (with meals and at bedtime).
Hypophosphatemia, chronic; prevention or maintenance treatment: Note: Dose should be individualized and may vary based on underlying etiology.
Infants, Children, and Adolescents: Oral: 2 to 3 mmol elemental phosphorus/kg/day in divided doses, usually at least 4 divided doses (Ref).
Internal contamination with radioactive phosphorus (P-32): Limited data available:
Children >4 years and Adolescents: Oral: 250 mg 4 times daily; adolescent dosing not defined in expert recommendations; in adults, doses of 250 to 500 mg 4 times daily suggested (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in the manufacturer's labeling; phosphorus accumulates in renal impairment. Contraindicated in patients with severe impairment (<30% of normal function).
There are no dosage adjustments provided in the manufacturer’s labeling. Use with caution.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Also see individual agents.
Frequency not defined:
Cardiovascular: Bradycardia, cardiac arrhythmia, chest pain, edema, lower extremity edema, tachycardia
Central nervous system: Confusion, dizziness, fatigue, headache, heaviness of the legs, numbness, paresthesia, seizure, tingling sensation, tetany (with large doses of phosphate)
Endocrine & metabolic: Alkalosis, hyperkalemia, weight gain
Gastrointestinal: Diarrhea, flatulence, nausea, oral paresthesia, sore throat, stomach pain, vomiting
Genitourinary: Decreased urine output
Local: Local pain (hands and feet)
Neuromuscular & skeletal: Arthralgia, asthenia, limb pain, muscle cramps, muscle weakness of the extremities, ostealgia, paralysis
Renal: Acute renal failure
Respiratory: Dyspnea
Miscellaneous: Increased thirst
Hyperphosphatemia; infected urinary phosphate stones; severe renal impairment (<30% of normal)
Concerns related to adverse effects:
• Hyperphosphatemia: Hyperphosphatemia managed with hemodialysis has been reported following excessive use of sodium phosphate enemas (Becknell 2014).
• Laxative effect: A mild laxative effect may occur within the first few days of therapy; if the laxative effect persists, reduce the dose or discontinue use until diarrhea improves.
Disease-related concerns:
• Adrenal insufficiency: Use with caution in patients with severe adrenal insufficiency (eg, Addison disease)
• Cardiac disease: Use with caution in patients with cardiac disease, including heart failure (especially patients receiving digoxin) and hypertension.
• Dehydration: Use with caution in patients with acute dehydration.
• Edema: Use with caution in patients with peripheral or pulmonary edema.
• Hepatic impairment: Use with caution in patients with cirrhosis or severe hepatic impairment.
• Hypernatremia: Use with caution in patients with hypernatremia.
• Myotonia congenita: Use with caution in patients with myotonia congenita.
• Pancreatitis: Use with caution in patients with acute pancreatitis.
• Parathyroid disease: Use with caution in patients with hypoparathyroidism.
• Renal calculi: Patients with renal calculi may pass preformed stones when phosphate therapy is initiated.
• Renal impairment: Use with caution in patients with renal impairment or chronic renal disease; use is contraindicated in patient with severe renal impairment (<30% of normal).
• Rickets: Use with caution in patients with rickets; may increase the risk of extraskeletal calcification.
• Tissue breakdown: Use with caution in patients with extensive tissue breakdown (eg, severe burns).
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Powder for solution, oral:
Phos-NaK: Dibasic potassium phosphate, monobasic potassium phosphate, dibasic sodium phosphate, and monobasic sodium phosphate per packet (100s) [sugar free; equivalent to elemental phosphorus 250 mg (8 mmol), sodium 160 mg (6.9 mEq), and potassium 280 mg (7.1 mEq) per packet; fruit flavor]
Generic: Dibasic potassium phosphate, monobasic potassium phosphate, dibasic sodium phosphate, and monobasic sodium phosphate per packet
Tablet, oral:
Av-Phos 250 Neutral: Monobasic potassium phosphate 155 mg, dibasic sodium phosphate 852 mg, and monobasic sodium phosphate 130 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 298 mg (13 mEq), and potassium 45 mg (1.1 mEq)]
K-Phos Neutral: Monobasic potassium phosphate 155 mg, dibasic sodium phosphate 852 mg, and monobasic sodium phosphate 130 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 298 mg (13 mEq), and potassium 45 mg (1.1 mEq)]
K-Phos No. 2: Potassium acid phosphate 305 mg and sodium acid phosphate 700 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 134 mg (5.8 mEq), and potassium 88 mg (2.3 mEq)]
Phospha 250 Neutral: Monobasic potassium phosphate 155 mg, dibasic sodium phosphate 852 mg, and monobasic sodium phosphate 130 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 298 mg (13 mEq), and potassium 45 mg (1.1 mEq)]
Phospho-Trin 250 Neutral: Monobasic potassium phosphate 155 mg, dibasic sodium phosphate 852 mg, and monobasic sodium phosphate 130 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 298 mg (13 mEq), and potassium 45 mg (1.1 mEq)]
Virt-Phos 250 Neutral: Monobasic potassium phosphate 155 mg, dibasic sodium phosphate 852 mg, and monobasic sodium phosphate 130 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 298 mg (13 mEq), and potassium 45 mg (1.1 mEq)] [DSC]
Generic: Monobasic potassium phosphate 155 mg, dibasic sodium phosphate 852 mg, and monobasic sodium phosphate 130 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 298 mg (13 mEq), and potassium 45 mg (1.1 mEq)]
Yes
Tablets (K-Phos No 2 Oral)
305-700 mg (per each): $1.22
Tablets (K-Phos-Neutral Oral)
155-852-130 mg (per each): $0.89
Tablets (Phospha 250 Neutral Oral)
155-852-130 mg (per each): $0.51
Tablets (Phospho-Trin 250 Neutral Oral)
155-852-130 mg (per each): $0.49
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.
Administer with a full glass of water at mealtime and at bedtime.
Oral powder: Must be diluted in water or juice prior to administration.
Oral:
Tablets: Administer with a full glass of water.
Oral powder (Phos-NaK): Each packet must be diluted in 75 mL of water or juice prior to administration; stir well and use promptly. Proper dilution may help prevent GI injury associated with concentrated oral potassium preparations.
Phosphate supplement: As a phosphorus supplement
Urinary acidification: To increase urinary phosphate and pyrophosphate
K-Phos No. 2: Urinary acidifier for patients with elevated urinary pH to help keep calcium soluble and reduce odor and rash caused by ammoniacal urine; increases the antibacterial activity of methenamine.
Internal contamination with radioactive phosphorus (P-32)
K-Phos Neutral may be confused with Neutra-Phos-K [DSC]
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.
Aliskiren: Potassium Salts may increase hyperkalemic effects of Aliskiren. Risk C: Monitor
Amantadine: Urinary Acidifying Agents may decrease serum concentration of Amantadine. Risk C: Monitor
AMILoride: Potassium Salts may increase hyperkalemic effects of AMILoride. Management: Amiloride and potassium supplements should not be used except in severe or refractory cases of hypokalemia. If coadministered, monitor serum potassium closely as rapid increases in potassium are possible. Risk D: Consider Therapy Modification
Amphetamines: Urinary Acidifying Agents may decrease serum concentration of Amphetamines. Risk C: Monitor
Angiotensin II Receptor Blockers: Potassium Salts may increase hyperkalemic effects of Angiotensin II Receptor Blockers. Risk C: Monitor
Angiotensin-Converting Enzyme Inhibitors: Potassium Salts may increase hyperkalemic effects of Angiotensin-Converting Enzyme Inhibitors. Risk C: Monitor
Antacids: May decrease serum concentration of Potassium Phosphate. Management: Consider separating administration of antacids and oral potassium phosphate by at least 2 hours to decrease risk of a significant interaction. Risk D: Consider Therapy Modification
Burosumab: Phosphate Supplements may increase adverse/toxic effects of Burosumab. Risk X: Avoid
Calcium Salts: May decrease absorption of Phosphate Supplements. Management: This applies only to oral phosphate and calcium administration. Administering oral phosphate supplements as far apart from the administration of an oral calcium salt as possible may be able to minimize the significance of the interaction. Risk D: Consider Therapy Modification
ChlorproPAMIDE: Urinary Acidifying Agents may increase serum concentration of ChlorproPAMIDE. Risk C: Monitor
CycloSPORINE (Systemic): May increase hyperkalemic effects of Potassium Phosphate. Management: Avoid coadministration of potassium phosphate and cyclosporine due to the risk of severe and potentially fatal hyperkalemia. If coadministration is required, monitor serum potassium concentrations closely. Risk D: Consider Therapy Modification
Digitoxin: Potassium Salts may increase adverse/toxic effects of Digitoxin. Potassium Salts may decrease therapeutic effects of Digitoxin. Risk C: Monitor
Digoxin: May increase hyperkalemic effects of Potassium Phosphate. Management: Avoid coadministration of potassium phosphate and digoxin due to the risk of severe and potentially fatal hyperkalemia. If coadministration is required, monitor serum potassium concentrations closely. Risk D: Consider Therapy Modification
Drospirenone-Containing Products: May increase hyperkalemic effects of Potassium Salts. Risk C: Monitor
Eplerenone: May increase hyperkalemic effects of Potassium Salts. Management: This combination is contraindicated in patients receiving eplerenone for treatment of hypertension. Potassium supplements may be needed to treat/prevent hypokalemia in select patients with heart failure receiving eplerenone and high dose loop diuretics. Risk D: Consider Therapy Modification
Erdafitinib: Serum Phosphate Level-Altering Agents may decrease therapeutic effects of Erdafitinib. Management: Avoid coadministration of serum phosphate level-altering agents with erdafitinib before initial dose increase period based on serum phosphate levels (Days 14 to 21). Risk D: Consider Therapy Modification
Finerenone: Potassium Salts may increase hyperkalemic effects of Finerenone. Risk C: Monitor
Heparin: May increase hyperkalemic effects of Potassium Salts. Risk C: Monitor
Heparins (Low Molecular Weight): May increase hyperkalemic effects of Potassium Salts. Risk C: Monitor
Iron Preparations: May decrease absorption of Phosphate Supplements. Management: Administer oral phosphate supplements as far apart from the administration of an oral iron preparation as possible to minimize the significance of this interaction. Risk D: Consider Therapy Modification
Magnesium Salts: May decrease serum concentration of Phosphate Supplements. Management: Administer oral phosphate supplements as far apart from the administration of an oral magnesium salt as possible to minimize the significance of this interaction. Risk D: Consider Therapy Modification
Mecamylamine: Urinary Acidifying Agents may decrease serum concentration of Mecamylamine. Risk C: Monitor
Multivitamins/Minerals (with ADEK, Folate, Iron): May decrease serum concentration of Phosphate Supplements. Management: Administer oral phosphate supplements as far apart from the administration of an iron-containing oral multivitamin as possible to minimize the significance of this interaction. Risk D: Consider Therapy Modification
Nicorandil: May increase hyperkalemic effects of Potassium Salts. Risk C: Monitor
Nonsteroidal Anti-Inflammatory Agents: May increase hyperkalemic effects of Potassium Salts. Risk C: Monitor
Salicylates: Potassium Phosphate may increase serum concentration of Salicylates. Risk C: Monitor
Spironolactone: Potassium Salts may increase hyperkalemic effects of Spironolactone. Risk X: Avoid
Sucralfate: May decrease absorption of Phosphate Supplements. Management: This applies only to oral phosphate administration. Administering oral phosphate supplements at least 2 hours before sucralfate may reduce the significance of the interaction. Risk D: Consider Therapy Modification
Tacrolimus (Systemic): May increase hyperkalemic effects of Potassium Phosphate. Management: Avoid coadministration of potassium phosphate and tacrolimus due to the risk of severe and potentially fatal hyperkalemia. If coadministration is required, monitor serum potassium concentrations closely. Risk D: Consider Therapy Modification
Triamterene: Potassium Salts may increase hyperkalemic effects of Triamterene. Risk X: Avoid
Uva Ursi: Urinary Acidifying Agents may decrease therapeutic effects of Uva Ursi. Management: Consider avoiding use of uva ursi with agents that acidify the urine, as this may impair uva ursi efficacy. Risk D: Consider Therapy Modification
Use with caution in patients with preeclampsia.
Also refer to individual monographs for additional information.
It is not known if potassium phosphate and sodium phosphate are present in breast milk. The manufacturer recommends that caution be exercised when administering potassium phosphate/sodium phosphate to breastfeeding women.
Also refer to individual monographs for additional information.
In addition to phosphate, products contain potassium and sodium.
Dietary reference intake (elemental phosphorus) (IOM 1997):
1 to 6 months: Adequate intake: 100 mg/day (3.2 mmol/day).
7 to 12 months: Adequate intake: 275 mg/day (8.9 mmol/day).
1 to 3 years: Recommended dietary allowance (RDA): 460 mg/day (14.8 mmol/day).
4 to 8 years: RDA: 500 mg/day (16.1 mmol/day).
9 to 18 years: RDA: 1,250 mg/day (40.3 mmol/day).
≥18 years: RDA: 700 mg/day (22.6 mmol/day).
Serum potassium, sodium, calcium, phosphorus, magnesium (to facilitate potassium repletion), and renal function at periodic intervals
Note: Reference ranges may vary depending on the laboratory
Serum potassium: 3.5 to 5 mEq/L (SI: 3.5 to 5 mmol/L).
Serum phosphorus: Both low and high ends of the normal range are higher in children than in adults.
Infants: 4.5 to 7.5 mg/dL (SI: 1.5 to 2.4 mmol/L)
Children: ~4 to 6 mg/dL (SI: ~1.3 to 1.9 mmol/L)
Adults: 3 to 4.5 mg/dL (SI: 1 to 1.5 mmol/L)
See individual agents.
Onset of action: Catharsis: Oral: 3 to 6 hours
Absorption: Oral: 1% to 20%
Excretion: Oral forms excreted in feces
