Trichomoniasis: Treatment

INTRODUCTION — Trichomoniasis is a genitourinary infection with the protozoan Trichomonas vaginalis. It is the most common nonviral sexually transmitted infection (STI) worldwide. Females are affected more often than males. Trichomoniasis is one of the three common infectious causes of vaginal complaints among reproductive-aged females, along with bacterial vaginosis (BV) and candida vulvovaginitis, and is a cause of urethritis in males; however, the infection is often asymptomatic.

The various clinical presentations of trichomoniasis and diagnostic tests are presented in related content. (See "Trichomoniasis: Clinical manifestations and diagnosis".)

The approach to patients with vaginal discharge and urethritis are discussed separately.

●(See "Vaginitis in adults: Initial evaluation".)

●(See "Urethritis in adult males".)

In this topic, we use the terms "women" or "men" as they are used in the studies presented. We encourage the reader to consider the specific counseling and treatment needs of transgender and gender-expansive individuals.

WHOM TO TREAT — Treatment is indicated for both symptomatic and asymptomatic persons with confirmed infection with T. vaginalis. Treatment has limited side effects, is associated with a high cure rate, likely reduces the prevalence of T. vaginalis carriage in the population, reduces transmission of the parasite, and reduces the risk of sequelae (including acquisition/transmission of HIV) [1,2].

5-NITROIMIDAZOLE DRUGS — The 5-nitroimidazole drugs provide curative therapy of trichomoniasis.

Overall efficacy — The 5-nitroimidazole drugs (metronidazole, tinidazole, and secnidazole) are the only class of drugs that provide curative therapy of trichomoniasis (algorithm 1) [3,4]. Most strains of T. vaginalis are highly susceptible to these agents [5]. Randomized trials using these drugs have generally reported cure rates of 90 to 95 percent [6-9]. Choice of agent is generally determined by availability, preference for single-day therapy, and cost. Management of nitroimidazole-resistant Trichomonas is discussed below. (See 'Patients with persistent symptoms' below.)

Drugs and descriptions

Metronidazole — Metronidazole is available in oral and topical formulations and in single- and multi-dose regimens. Selection is determined by patient characteristics (eg, pregnant or not), patient preferences, and drug availability. (See 'Treatment regimens' below.)

●Oral preferred to vaginal dosing – Cure rates for vaginal therapy with metronidazole gel are ≤50 percent, which is significantly lower than with oral therapy, and therefore therapy with topical metronidazole is not recommended [1,10,11]. In a meta-analysis of two trials comparing oral versus vaginal metronidazole, use of oral metronidazole was 80 percent more likely to result in parasitological cure compared with vaginal therapy (risk ratio 0.20, 95% CI 0.07 to 0.56, n = 94) [8]. Treatment with vaginal metronidazole gel does not reach therapeutic levels in the urethra and paravaginal glands, which serve as endogenous reservoirs of organisms that can cause disease recurrence.

●Multi-dose compared with single-dose metronidazole therapy

•Data supporting multiday treatment for female patients – While single- (2 g) and multi-dose (500 mg twice daily for seven days) oral metronidazole treatment options are reasonable, multi-dose treatment is preferred based on studies in HIV-uninfected women reporting of higher cure rates following multi-dose treatment (multi-dose cure rates of 89 to 92 percent versus single-dose cure rates of 81 to 86 percent) [6,12,13]. In a systematic review including five studies comparing multi-dose with single-dose therapy in women without HIV infection, single-day treatment was 80 percent more likely to be associated with treatment failure (pooled risk ratio of 1.80, 95% CI 1.07-3.02) [13]. At least one study reported similar adherence for single- and multiday regimens (99 versus 96 percent, respectively) [12]. Selection varies by the patient characteristics (eg, pregnant or not) and preferences. Either dosing regimen is associated with side effects (eg, nausea, vomiting, headache, metallic taste, dizziness); these effects appear to be dose-related and thus occur less frequently with the lower doses used in multi-dose therapy [8,14]. The authors reserve single-dose therapy for female patients who are unable to complete a multi-dose treatment course of metronidazole.

•Data supporting single-dose metronidazole treatment for male patients – Single-dose therapy for male patients is generally preferred because of ease of single dosing, although efficacy may be lower than that of multi-dose metronidazole therapy [15,16]. However, trial data are limited. In a trial including 325 males comparing a single 2 g oral dose of metronidazole and metronidazole 400 mg three times daily for five days, treatment failure occurred in 43 percent of the single-dose patients and none of the multi-dose patients [16]. Until data from an adequately powered trial are available, both dosing regimens are reasonable and patient preference, usually for single-dose treatment, determines treatment choice. The authors extrapolate this approach to individuals who have undergone surgical phalloplasty, although the authors are unaware of a reported case of trichomoniasis in a patient with phalloplasty.

Tinidazole — Tinidazole, given as a single 2 g oral dose, is an alternative treatment for trichomonas infection for females and males [1,17,18]. In addition, the World Health Organization (WHO) lists tinidazole 500 mg orally twice daily for five days as an alternative, although it is not clear which patients may benefit most from longer duration of initial treatment [17]. In addition, the relative efficacy of either tinidazole dose compared with single- and multi-dose metronidazole is unclear. Although tinidazole was significantly more effective than metronidazole in several randomized trials including women, most of these trials were subject to bias since outcome was assessed by clinicians who were not blinded to the patient's treatment group [8]. Data specific to male patients are limited. In one trial comparing oral tinidazole 1 g with oral metronidazole 1.5 g in 73 men with trichomoniasis, all had negative T. vaginalis cultures at 14 and 30 days post treatment [19].

Compared with metronidazole, tinidazole generally causes fewer gastrointestinal side effects, but the cost may be higher and the drug may be less commercially available.

Secnidazole — Secnidazole is a 5-nitroimidazole with a longer half-life (17 to 19 hours) than oral metronidazole (7 to 8 hours) and tinidazole (12 to 13 hours) [20]. It is given as a single 2 g oral treatment for trichomoniasis [21]. It is administered as a packet of granules which should be sprinkled onto a standard serving of applesauce, yogurt, or pudding and consumed within 30 minutes [22]. Single-dose secnidazole is the only oral treatment option for both trichomoniasis and bacterial vaginosis (BV) in patients with a vagina [23].

●Efficacy – Compared with placebo for treatment of trichomoniasis in females, cure rates of 92 percent were reported at 6- to 12-day follow-up, which is comparable to other 5-nitroimidazole single-dose regimens in this short-term follow-up period [9,13]. Gastrointestinal side effects were reported in <5 percent of participants in either arm, which is lower than rates reported with single-dose metronidazole [12]. Data for using secnidazole in males with trichomoniasis are limited. In one trial comparing ornidazole, metronidazole, or secnidazole treatment in 85 men with confirmed trichomoniasis, all three treatment groups tested negative (by microscopic evaluation and culture of discharge) and were asymptomatic at follow-up evaluation [24].

●Limitations – While secnidazole may be preferred by patients for its single-day dosing, the cost may be higher because it is a newer treatment. Additionally, there are no head-to-head efficacy comparisons of single-dose secnidazole and the seven-day metronidazole regimen for the treatment of trichomoniasis in females or males.

Concerns with alcohol ingestion — Previous guidelines and package label inserts have recommended avoiding alcohol ingestion while taking metronidazole due to a potential disulfiram-like reaction associated with 5-nitroimidazoles [14]. However, several authors have reviewed the cases that are the basis of these reports and have not identified any convincing data to suggest that this is a true association [25-28]. Disulfiram inhibits acetaldehyde dehydrogenase, leading to increased concentrations of acetaldehyde, while in vitro experiments show a decrease in acetaldehyde with addition of metronidazole [29]. Thus, we do not believe that patients need to be counseled to avoid alcohol while using metronidazole and extrapolate this approach to tinidazole and secnidazole.

TREATMENT REGIMENS — Treatment is indicated in all persons diagnosed with trichomoniasis, even if asymptomatic, and their sex partners (algorithm 1). We use the regimens below, which are in agreement with the World Health Organization (WHO) and/or the US Centers for Disease Control and Prevention (CDC), except as noted [1,17].

Females

Nonpregnant — Nonpregnant females are preferentially treated with a multi-dose oral metronidazole regimen rather than single-day treatment because multi-dose therapy is associated with improved cure rates at one month [12,13].

●Preferred – Metronidazole 500 mg, tablet or capsule, orally twice daily for seven days [1,17,18,30-32]. The authors prefer this approach because of higher efficacy compared with single-day regimens [12,13]. An oral suspension is also available with unique dosing (metronidazole oral suspension 250 mg [2.5 mL] orally three times daily for seven days) [33]. (See 'Metronidazole' above.)

●Alternatives – Alternative treatments vary according to the source guideline (CDC compared with WHO). As direct comparative data are lacking, selection is based on availability and cost.

•Single-dose options – Treatment with a single 2 g oral dose of either metronidazole or tinidazole (ie, four 500 mg tablets) is associated with lower rates of cure compared with metronidazole multi-dose therapy [1,8]. The authors reserve single-dose therapy for those who are unable to complete a multi-dose treatment course.

-Metronidazole 2 g orally given as a single dose [17] or metronidazole oral suspension 2 g (20 mL), either as a single oral dose or in two divided oral doses of 1 g (10 mL) each, given on the same day [33]. (See 'Metronidazole' above.)

OR

-Tinidazole 2 g orally given as a single dose [1,18]. (See 'Tinidazole' above.)

OR

-Secnidazole 2 g orally given as a single dose [9,34] (single-dose secnidazole is effective treatment for both trichomoniasis and bacterial vaginosis). (See 'Secnidazole' above and "Bacterial vaginosis: Initial treatment", section on 'Secnidazole'.)

•Multi-dose tinidazole – Tinidazole 500 mg orally twice daily for five days is an alternative option listed by WHO [17]. It is not yet known which patient groups may benefit from multi-dose tinidazole compared with single-dose for initial treatment. We reserve multi-dose tinidazole for patients with persistent infection despite adequate initial treatment and use a higher dose in this setting (tinidazole 2 g daily for seven days [1]). (See 'Treatment' below.)

●Not advised – Vaginal metronidazole gel is not recommended because it does not effectively treat all anatomic reservoirs of infection and should not be used to treat trichomoniasis [1]. However, metronidazole vaginal gel remains on at least one treatment guideline [17]. (See 'Metronidazole' above.)

Pregnant — Treatment of pregnant persons, with or without symptoms, is indicated as T. vaginalis infection is common in pregnant persons and has been associated with adverse pregnancy outcomes [1,35,36]. (See "Trichomoniasis: Clinical manifestations and diagnosis", section on 'Female'.)

Treatment and dosing options

●Preferred – Metronidazole 500 mg orally twice daily for seven days, regardless of trimester [1,17]. An oral suspension is also available (metronidazole oral suspension 250 mg [2.5 mL] orally three times daily for seven days) [33].

This is our preferred regimen as we believe the available evidence supports the benefits of treatment, including reduced partner and perinatal transmission, and outweighs potential risks, although at least one organization advises waiting until after the first trimester for treatment, if possible [17].

●Alternate regimens – WHO lists the following as alternative treatment options with the notation to avoid metronidazole use in the first trimester of pregnancy if possible [17]. While data directly comparing the treatment options in pregnant persons are lacking, there is no reason to think that pregnancy would make the alternative regimens more effective than multi-dose oral metronidazole.

•Metronidazole 2 g orally in a single dose [17]. An oral suspension is also available (metronidazole oral suspension 2 g [20 mL], either as a single oral dose or in two divided oral doses of 1 g [10 mL] each, given on the same day) [33]. While single-day dosing is included as a first-line treatment option in the WHO sexually transmitted infection (STI) treatment guidelines, we view it as an alternative for the reasons discussed above. However, both single- and multiple-dose regimens are acceptable as there are no specific data comparing single-dose and multiple-dose regimens in pregnant individuals and there are no reasons to think that efficacy is different in pregnant patients. In our practices, we reserve the single-dose regimen for pregnant individuals who are unable to complete seven days of treatment or prefer single-dose therapy.

OR

•Metronidazole 200 or 250 mg orally three times daily for seven days [17]. These doses may not be universally available.

●Not advised during pregnancy – In our practices, we do not use metronidazole gel, tinidazole, or secnidazole in pregnant persons.

•Metronidazole vaginal gel does not effectively treat all anatomic reservoirs of infection and is not advised [1], although at least one guideline lists metronidazole gel as a third-line treatment option [17].

•Tinidazole and secnidazole – We avoid oral tinidazole or secnidazole, especially in the first trimester, as safety data from human pregnancies are insufficient to make a definitive conclusion regarding teratogenicity and some, but not all, animal data suggest risk [1,21,23,37,38].

Teratogenicity — While metronidazole crosses the placenta [39], it appears to be low risk to the developing fetus. Cross-sectional and cohort studies have not reported teratogenicity or mutagenic effects for single- or multi-dose metronidazole treatment in humans (although studies suggest the drug is mutagenic in bacteria and carcinogenic in mice) [40-44]. There is limited information on the safety of tinidazole or secnidazole in pregnancy and thus we do not advise use of these drugs during pregnancy [1,21,23,37,38].

Males — While other treatment options exist, preferred treatment for male patients with confirmed trichomoniasis include:

●Preferred – Metronidazole 2 g orally in a single dose [1,17,32]. If the oral suspension is preferred to tablets or capsules, the dosing is: metronidazole oral suspension 2 g (20 mL), either as a single oral dose or in two divided oral doses of 1 g (10 mL) each, given on the same day [33].

●Alternatives

•Tinidazole 2 g orally in a single dose [1,19].

OR

•Secnidazole 2 g orally given as a single dose [9,24,34].

OR

•Metronidazole, 400 or 500 mg, orally twice daily for seven days [17]. Dose selection is based on availability and type of oral formulation; the 500 mg dose of metronidazole is more commonly available. If the oral suspension is preferred, it is given as 250 mg (2.5 mL) orally three times daily for seven days [33]. Although data supporting a longer course of therapy are lacking, this approach is described for individuals with recurrent or persistent infection [17].

The clinical evaluation and management of individuals with urethritis are discussed in detail separately. (See "Urethritis in adult males".)

Sex partners — All sex partners (female and/or male) of patients treated for trichomoniasis are treated concurrently with the goal of preventing reinfection of the index patient and/or spread to other sex contacts [1].

●Treatment selection – Treatment selection is based on the individual's characteristics (eg, pregnant or not, genital anatomy, dosing preferences) and as presented above. (See 'Treatment regimens' above.)

●Option for expedited partner treatment – Ideally, all sex partners undergo their own evaluation for trichomoniasis and other STIs but expedited partner therapy (EPT) is reasonable where permitted [45,46].

●Abstinence from sexual activity – After completion of therapy (single- or multi-dose), the patient and their sex partners should abstain from intercourse until all partners have completed antibiotic therapy and symptoms have resolved [1]. There are no studies on how long trichomonads remain viable after treatment is initiated or completed. We counsel patients to abstain from anal intercourse as well because trichomonads have been found in rectal samples and an anal reservoir of organisms could be a source of reinfection [47].

●Concurrent carriage rates – Concurrent carriage rates of 30 to 70 percent have been reported in male sex partners [48]. Concurrent carriage rates for female sex partners of female patients are not known.

Additional counseling — Additional counseling for patients with confirmed trichomoniasis, or their sex partners, includes:

●Sexual activity – Avoid genital sexual activity until all sex partners have completed antibiotic treatment and are asymptomatic [1].

●STI testing – Testing for other STIs, including HIV, syphilis, gonorrhea, and chlamydia, and treatment as indicated, is advised for patients with confirmed infection and their sex partners [1]. (See "Screening for sexually transmitted infections".)

REPEAT TESTING AFTER TREATMENT

●Female – We retest all female patients who were treated for a documented Trichomonas infection, regardless of whether they believe their sex partners were treated [1]. The rationale is that rates of persistent infection or reinfection are high. Retrospective studies have reported positive retest rates of 24 to 44 percent for patients undergoing nucleic acid amplification tests (NAATs) within the guideline time frame [49,50]. A single study in pregnant people, in which diagnosis could be made using NAAT or wet mount, found a similarly high prevalence of 29 percent upon retesting [36]. (See "Polymerase chain reaction (PCR)".)

•Repeat testing is ideally performed with a NAAT, which can be done no sooner than three weeks [51] and up to three months after completing treatment, regardless of whether or not sex partner(s) were treated [1].

•If testing is not possible within three months of initial treatment, then testing is advised up to 12 months from initial treatment [1].

•If NAATs are not available, retesting with the same modality used to make the initial diagnosis (or a more sensitive test) is advised.

●Male – Data to inform retesting previously treated male patients are lacking; there is no recommendation to retest these patients unless they are symptomatic [1].

PATIENTS WITH PERSISTENT SYMPTOMS — Most cases of persistent symptoms result from inadequate initial treatment or reinfection by an untreated sex partner. Some patients will have persistent infection despite adequate initial treatment.

Diagnostic approach — We take the following approach:

●Patient history – Take a detailed history to determine if the persistent symptoms are likely from inadequate initial treatment or reinfection.

●Diagnostic test – Retest patients with persistent symptoms with nucleic acid amplification testing (NAAT) to confirm trichomonas as the cause of the persistent symptoms as patients can have more than one infection. NAAT should not be repeated sooner than three weeks from completion of prior treatment because of potential for false-positive results [1,51]. (See "Trichomoniasis: Clinical manifestations and diagnosis", section on 'Preferred tests'.)

●Exclude other causes – Other potential sources of symptoms, such as vulvovaginal candidiasis, bacterial vaginosis (BV), and the sexually transmitted infections gonorrhea and chlamydia, are excluded with appropriate tests. (See "Vaginitis in adults: Initial evaluation", section on 'Test vaginal discharge'.)

Treatment — Treatment is based on diagnostic test results. As coinfection is common, all diagnosed potential causes of the patient's symptoms (eg, candidiasis, BV, trichomonas) are treated as indicated.

For patients with confirmed persistent or recurrent trichomoniasis, we proceed through the treatment approaches as listed:

●Inadequate initial treatment – The most common cause of continued symptoms and infection is medication misuse or early discontinuation that results in a persistent vaginal reservoir of organisms. For patients with recurrent symptoms and likely inadequate initial treatment, we discuss obstacles to completing therapy, explore possible solutions, and retreat with the initial regimens as above. Use of single-dose drugs may enhance medication completion in drug intolerant patients. (See 'Treatment regimens' above.)

●Reinfection by sex partner – Reinfection from untreated or undertreated sexual partners is common. For patients with recurrent trichomoniasis in whom reinfection by a sex partner is likely, we repeat treatment of the patient, and all sex partners, with the originally selected treatment regimen as presented above. (See 'Treatment regimens' above.)

●Persistent infection – Persistent infection can occur despite appropriate treatment of the patient and all sex partners. Once inadequate initial treatment and/or reinfection from a sex partner have been excluded, we retreat the index patient and all sex partners as follows:

•Longer duration of treatment – Individuals with symptom recurrence after single-dose oral metronidazole 2 g should be treated with oral metronidazole 500 mg twice daily for seven days (total dose 7 g) [1,31].

•Increased dose and duration of treatment – If the patient has persistent trichomonas infection despite multi-dose treatment, we then treat with higher doses of oral tinidazole or metronidazole.

-Females – Metronidazole or tinidazole 2 g orally once a day for seven days (total dose 14 g) can be used [1,31]. This approach can also be effective in patients with low levels of metronidazole resistance, which was noted in 4 percent of 538 T. vaginalis isolates collected from women attending STD clinics in six cities in the United States [52].

-Males – Metronidazole 2 g orally once daily for seven days (total dose 14 g) is advised [1].

Drug-resistant infection — If the above treatment regimens fail and NAAT confirms persistent trichomonas infection, next steps include in vitro culture and drug susceptibility testing and patient referral to a specialist [4]. One option for culture and drug sensitivity testing is available through the United States CDC Infectious Disease Laboratories. Metronidazole-resistant T. vaginalis has been documented [53-55]. Cross resistance to tinidazole is frequent but not inevitable [53,56]. For secnidazole, trichomoniasis isolates requiring a minimum inhibitory concentration similar to that of metronidazole have been reported [55]. In an in vitro study of trichomonas isolates in South Africa, resistance to metronidazole was more common (11 percent) than tinidazole (2 percent) or secnidazole (1 percent) [3].

Treatment options for patients with metronidazole-resistant infection include:

●High-dose tinidazole – Refractory disease has been successfully treated with high-dose oral tinidazole, although the optimal dose, regimen, and combination with other drugs have not been established [4,57-59]. Choice of treatment is based on availability of the drugs below.

•Tinidazole only – Oral tinidazole 2 g daily for 14 days plus vaginal tinidazole 500 mg twice a day for 14 days (total drug dose 42 g) [57].

•Tinidazole plus vaginal boric acid – Tinidazole, 1 g orally three time a day for 14 days plus vaginal boric acid, 600 mg, twice daily for 28 days successfully treated a female patient with confirmed T. vaginalis infection resistant to both metronidazole and tinidazole [60]. Boric acid should never be given orally as it can cause death.

•Tinidazole plus vaginal paromomycin – Tinidazole 1 g orally three times a day plus vaginal paromomycin 6.25% given as 4 g intravaginally at night (ie, 250 mg of drug per dose), both for a total of 14 days, has been reported in one patient [61]. Additional information on vaginal paromomycin is presented in the bullet below.

●Secnidazole – Data supporting secnidazole treatment of drug-resistant trichomoniasis is limited to one case report. A patient with confirmed metronidazole- and tinidazole-resistant infection was successfully treated with an investigational protocol of secnidazole 2 g orally daily for 14 days combined with boric acid 600 mg suppository vaginally twice daily for 14 days [62]. Four weeks after completing treatment, the patient’s symptoms had resolved and test of cure was negative by wet mount, culture, and NAAT.

●Vaginal paromomycin – Rare patients who do not have a response to 5-nitroimidazoles have been treated with the aminoglycoside paromomycin. Paromomycin 6.25% cream is given as a 4 g intravaginal dose (ie, 250 mg of drug) daily for two weeks) [63]. Dual therapy combining intravaginal paromomycin 6.25% cream, 4 g intravaginally at night, with oral tinidazole, 1 g three times daily, for a total of 14 days, has been reported [61]. Intravaginal paromomycin can cause local side effects (pain, mucosal ulceration) but these symptoms are self-limited [64,65]. Applying lubricating jelly to the vaginal tissue prior to vaginal paromomycin application has been reported to reduce ulceration in some patients [65]. Paromomycin is not available commercially in the United States as a cream and must be compounded by a specialty pharmacy. For this reason, we consider it a third-line option when the above regimens have not worked.

●Vaginal boric acid – Successful treatment of drug-resistant trichomoniasis has been reported with vaginal boric acid, alone [66] or combination with other drugs (eg, secnidazole [62] or clotrimazole [67]).

●Limited data – Case reports have described successful use of nimorazole, ornidazole, niridazole, furazolidone, and hamycin [68].

●Not advised – Other topical agents that have a limited (<50 percent) cure rate and therefore are not recommended include vaginal povidone-iodine, clotrimazole, acetic acid, furazolidone, gentian violet, nonoxynol-9, and potassium permanganate [69]. A trial of nitazoxanide in three women with difficult to eradicate T. vaginalis reported lack of efficacy [70].

UNIQUE POPULATIONS

Allergy to 5-nitroimidazole drugs — Given the low efficacy of alternate drug therapies, we suggest patients with an IgE-mediated allergy to metronidazole or tinidazole be referred for desensitization rather than using an alternative class of drugs [1,65]. In one series, all 15 people who underwent desensitization subsequently eradicated their infection [71]. (See "An approach to the patient with drug allergy".)

Data supporting treatment options for patients who cannot undergo or do not respond to desensitization therapy are limited. In a case report of one patient who was unable to complete metronidazole desensitization therapy, the individual with successfully treated with tinidazole [72]. A single case report describes successful treatment with secnidazole in a person with reported metronidazole hypersensitivity [73]. Therapy with drugs other than 5-nitroimidazoles is an option, but cure rates have been low (≤50 percent) [10,74]. Case reports have noted microbiologic and symptomatic cure following long-term treatment with vaginal boric acid, 600 mg intravaginally twice daily, alone or in combination with other agents, for at least 60 days [65].

Lactation — Metronidazole is the preferred drug for use in lactating patients.

●Metronidazole

•Our approach – We treat breastfeeding individuals with metronidazole 500 mg orally twice a day for seven days. The drug dose received through breast milk is lower than what would be used for to treat infection in infants [1,75].

•Alternate dose – Metronidazole 400 mg orally three times a day for seven days.

While one study reported that three times daily dosing produced a lower metronidazole concentration in breast milk [76], limitations include that the study included only seven infants, more frequent dosing may be more challenging for patients, and 400 mg tablets are not universally available.

•Option to defer breastfeeding (ie, pump and dump) – Although adverse effects have not been reported from infant exposure to maternal oral metronidazole, some clinicians advise deferring breastfeeding for 12 to 24 hours following maternal single-dose treatment because the relative infant dose of metronidazole is high (29 percent) with maternal administration of the 2 g one-time dose [77]. For patients who wish to avoid any metronidazole exposure to their infants, we advise pumping and expelling breast milk for 12 hours. Comparative data for the 12- and 24-hour time windows are lacking; deferring breastfeeding for 24 hours may be challenging.

●Tinidazole – Lactating patients who require treatment with oral tinidazole, which has a longer half-life than metronidazole, are advised to defer breastfeeding (ie, pump and dump) for 72 hours (three days) after a single 2 g dose [1]. Although data from human studies are limited, animal studies suggest tinidazole may be associated with risk to the infant. (See 'Teratogenicity' above.)

●Secnidazole – Data on safety of secnidazole use during lactation are lacking. Given the long half-life of the drug (approximately 17 hours), the manufacturer advises avoiding giving milk to the infant for 96 hours after a single dose [78,79].

HIV infection

●Treatment and retesting

•Female – Female patients with HIV infection and T. vaginalis are treated with metronidazole 500 mg twice per day for seven days [1,80]. We do not use single-dose metronidazole in this population given the high prevalence of asymptomatic bacterial vaginosis (BV) coinfection and other factors that may render single-dose oral metronidazole less effective. Female patients are retested for trichomoniasis three months after completion of therapy, preferably with NAAT. (See "Trichomoniasis: Clinical manifestations and diagnosis", section on 'Preferred tests'.)

•Male – Male patients receive the same treatment and retesting approaches regardless of HIV infection status. Treatment with metronidazole 2 g in a single oral dose is advised; retesting of male patients is not recommended at this time [1].

•Sex partners – As with other populations, sex partners of HIV-infected patients with T. vaginalis infection should be treated as well. (See 'Sex partners' above.)

●Supporting data for multi-dose metronidazole for female patients

•In a trial where 270 HIV-positive women with culture-confirmed T. vaginalis were randomly assigned to treatment with metronidazole 2 g single dose or metronidazole 500 mg twice per day for seven days, single-dose therapy was less effective than multi-dose therapy [80]. The seven-day treatment group had a lower rate of positive cultures 6 to 12 days after treatment completion (8.5 percent [11 in 130 women] versus 16.8 percent [21 in 125 women]; relative risk [RR] 0.5, 95% CI 0.25-1.00) and at three months (11 percent [8 in 73 women] versus 24.1 percent [19 in 79 women]; RR 0.46, 95% CI 0.21-0.98). Of note, all women were given a 2 g oral metronidazole dose to deliver to their sex partners.

•In another trial, HIV-infected women on antiretroviral therapy had 2.6-fold greater risk of persistent trichomoniasis than HIV-infected women not on antiretroviral therapy, but this risk could be minimized by multiday dosing [81].

●Bacterial vaginosis coinfection – There is a high prevalence of BV in patients with concurrent HIV and T. vaginalis infection and an apparent association between the presence of BV and early failure of single-dose oral metronidazole treatment of trichomoniasis [82].

•(See "HIV and women", section on 'Bacterial vaginosis, genital ulcers, and pelvic inflammatory disease'.)

•(See "Bacterial vaginosis: Initial treatment".)

Immunosuppression — We treat immunosuppressed patients with metronidazole 500 mg orally daily for seven days. As limited data are available to address the wide spectrum of immunosuppression, treatment of these patients is extrapolated from data based on patients with HIV infection.

Transgender individuals — There are no available data indicating that hormone therapy or surgery should alter trichomoniasis treatment or retesting recommendations. We extrapolate from the above data to transgender patients and treat or retest based on the patient's anatomy.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Sexually transmitted infections".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Trichomoniasis (The Basics)")

RESOURCES FOR PATIENTS AND CLINICIANS — The following resources are available to patients and clinicians at no cost.

●World Health Organization (WHO) – Guidelines for the management of symptomatic sexually transmitted infections

●National Health Service (UK) – Trichomoniasis

●US Centers for Disease Control and Prevention (CDC) – STI Treatment Guidelines

●American College of Obstetricians and Gynecologists – Vaginitis in Nonpregnant Patients

SUMMARY AND RECOMMENDATIONS

●Whom to treat – As with any sexually transmitted infection (STI), treatment is indicated for all persons with confirmed T. vaginalis infection, symptomatic and asymptomatic, as well as their sexual partners (even if asymptomatic). Treatment has limited side effects, is associated with a high cure rate, likely reduces the prevalence of T. vaginalis carriage in the population, reduces transmission, and reduces the risk of sequelae (including acquisition/transmission of HIV and adverse pregnancy outcomes). (See 'Whom to treat' above.)

●Therapeutic drugs and selection – The 5-nitroimidazole drugs (metronidazole, tinidazole, and secnidazole) are the only class of drugs that cure trichomonas infection (algorithm 1). Selection is based on patient characteristics (eg, genital anatomy, pregnancy), patient preferences regarding dosing, and drug availability. (See 'Drugs and descriptions' above.)

●Female patients

•Preferred – For female patients, including those who are pregnant (regardless of trimester), we suggest multi-dose therapy with oral metronidazole (preferred, capsule or tablet 500 mg orally twice daily for seven days, or oral suspension 250 mg (2.5 mL) orally three times daily for seven days) (algorithm 1) (Grade 2C). Treatment with metronidazole vaginal gel is not effective and should not be used to treat trichomoniasis. (See 'Females' above.)

•Alternatives

-Nonpregnant – For nonpregnant females, alternative treatments include single-dose tinidazole or secnidazole (2 g orally once for either drug) or metronidazole oral suspension [2 g (20 mL) as a single dose or in two divided doses of 1 g (10 mL) each, given on the same day]. Single-dose treatment may appeal to those who are unable to complete a seven-day treatment regimen or who prefer single-day dosing. (See 'Nonpregnant' above.)

-Pregnant – Single-day metronidazole is a reasonable treatment option for pregnant persons who are unable to complete a seven-day course of treatment. However, we do not use tinidazole or secnidazole during pregnancy, especially in the first trimester, as data from human pregnancies are limited and studies in animals suggest risk. (See 'Pregnant' above.)

●Male patients

•Initial episode – For male individuals, we suggest single-dose treatment with metronidazole, tinidazole, or secnidazole (2 g orally given once) (Grade 2C). Single-day therapy with an oral 5-nitroimidazole is easier to use compared with multi-dose regimens. Although treatment efficacy may be lower with single-dose metronidazole compared with multi-dose regimens, the available data are inadequate to make a definitive conclusion. Choice of drug is based on availability and cost. For patients unable to tolerate capsules or tablets, metronidazole oral suspension is available. (See 'Males' above.)

•Recurrent infection – Patients who have recurrent or persistent infection despite single-dose treatment may reasonably be treated with a seven-day course of oral metronidazole (capsule or tablet 500 mg orally twice daily for seven days, or oral suspension 250 mg [2.5 mL] orally three times daily for seven days), although supporting data are lacking.

●Sex partners – For all sex partners of patients with confirmed trichomoniasis, we suggest concurrent treatment for trichomoniasis rather than observation (Grade 2C). Treatment selection is based on the individual's anatomy. Ideally, all sex partners should undergo their own evaluation for trichomoniasis and other STIs but expedited partner therapy (EPT) is reasonable where permitted. (See 'Sex partners' above.)

●HIV infection – Patients with HIV infection receive the same treatment approach as listed above. For patients with a vagina, preferred treatment is metronidazole 500 mg orally twice daily for seven days because shorter treatment duration is associated with lower treatment efficacy. (See 'HIV infection' above.)

●Transgender patients – In the absence of data to inform practice, we extrapolate the above treatment approaches to transgender patients based on their genital anatomy. (See 'Transgender individuals' above.)

●Additional counseling points

•Sexual activity – Patients with confirmed trichomonas and their sex partners should avoid genital and anal sexual activity until all sex partners have completed treatment and are asymptomatic. (See 'Additional counseling' above.)

•STI testing – Patients with confirmed trichomonas and their sex partners are offered testing for HIV and other STIs. For those who cannot access evaluation and treatment, EPT is a reasonable option where permitted. (See 'Additional counseling' above.)

●Repeat testing – Female patients treated for a documented trichomonas infection should be retested with nucleic acid amplification tests (NAATs) between three weeks and three months of completing treatment. As data to inform an approach for male patients are inadequate, there is no recommendation to retest these patients unless they are symptomatic. In absence of data to inform practice, we extrapolate these approaches to transgender patients. (See 'Repeat testing after treatment' above.)

●Refractory infection – Treatment with an increased dose and/or duration of metronidazole or tinidazole are the primary options for patients with refractory trichomoniasis. (See 'Patients with persistent symptoms' above.)