Trichomoniasis is the most common non-viral sexually transmitted infection (STI) globally, affecting millions of people each year. This infection is caused by the single-celled protozoan parasite, Trichomonas vaginalis, not a bacterium. Although many search for an “antibiotic,” the effective medicine belongs to a class of antiprotozoal agents. The goal of treatment is to eliminate the parasite completely, resolving the infection and preventing further transmission. The treatment regimen is highly effective, with cure rates reaching up to 95%.
Treating the Infection
Treatment relies almost exclusively on medications from the nitroimidazole class, which are highly effective against the T. vaginalis parasite. The two primary medications used are metronidazole and tinidazole. Both drugs work by being absorbed into the parasitic cell, where they are chemically reduced into active compounds that disrupt the parasite’s DNA, leading to cell death. Metronidazole is generally considered the first-line treatment and is widely available. Tinidazole is an alternative drug with a longer half-life, meaning it stays in the body longer. It may also be prescribed if initial metronidazole treatment fails due to suspected drug resistance.
Dosing Schedules and Safety Instructions
Treatment protocols are tailored, with two main options available for both metronidazole and tinidazole. For women, the preferred regimen is metronidazole 500 milligrams taken orally twice a day for seven consecutive days. For men, the primary treatment is often a single, high-dose administration of 2 grams of metronidazole. An alternative for both sexes is a single, high-dose of 2 grams of tinidazole.
Safety Guidelines
Strict adherence to safety guidelines is necessary, particularly concerning alcohol consumption. Nitroimidazole drugs interact severely with alcohol, causing a disulfiram-like reaction that results in severe nausea, vomiting, and rapid heart rate. Patients must avoid all alcohol during treatment and for a specific time afterward. For metronidazole, abstinence should continue for at least 24 hours after the final dose, while tinidazole requires 72 hours due to its longer half-life. Patients may also experience common, temporary side effects like a metallic taste in the mouth or generalized nausea.
Ensuring Complete Eradication
Achieving a cure requires steps beyond simply completing the medication, focusing on preventing reinfection and confirming eradication. Simultaneous treatment of all recent sexual partners is necessary to break the cycle of infection, often called “ping-pong” transmission. Healthcare providers may use expedited partner therapy (EPT) to facilitate this process by providing the patient with medication for their partner. Sexual activity should be avoided until both the patient and all partners have finished their medication and symptoms have fully resolved, typically about one week. Due to the high rate of re-infection in women, a follow-up Test of Cure (TOC) is strongly recommended approximately three months after the initial treatment is completed. If initial treatment fails and resistance is suspected, a higher dose or longer course of metronidazole or tinidazole may be needed.