Fasigyn (tinidazole) is a nitroimidazole antimicrobial used to treat certain protozoal infections and bacterial vaginosis. In the U.S., tinidazole is indicated for trichomoniasis, giardiasis (age 3 and older), amebiasis (age 3 and older), and bacterial vaginosis in non-pregnant adult women.
What is Fasigyn Used For?
Tinidazole should be used only for infections that are proven or strongly suspected to be caused by susceptible organisms. It's not effective against viruses (such as colds or flu), so don't use it for viral infections.

If it seems suspicious that a specialist has prescribed these tablets, don't hesitate to ask questions. Also, keep in mind that this medicine is only available with a doctor's prescription.
Trichomoniasis (sexually transmitted infection)
Tinidazole is indicated for the treatment of trichomoniasis caused by Trichomonas vaginalis. Because trichomoniasis is a sexually transmitted disease, sexual partners should be treated with the same dose and at the same time to prevent re-infection.
Bacterial vaginosis (BV)
Tinidazole is indicated for the treatment of bacterial vaginosis in non-pregnant adult women.
Infections caused by organisms called protozoa
Tinidazole is indicated for giardiasis caused by Giardia duodenalis and for intestinal amebiasis and amebic liver abscess caused by Entamoeba histolytica (in adults and in children age 3 and older).
Infection associated with stomach ulcers in combination with other drugs
Tinidazole may be used off-label as part of some Helicobacter pylori eradication regimens in combination with other medicines. Use only if prescribed by a clinician for this purpose.
In all uses, the active ingredient is tinidazole, so you may see this name often when looking for information on Fasigyn tablets.
How to take Fasigyn Tablets
Take tinidazole with food to help reduce stomach upset. Swallow tablets with water (about 100 mL / about 3.4 fl oz). If you have trouble swallowing, ask your pharmacist or doctor for advice (tablets may be crushed and mixed with syrup only if directed by a healthcare professional).
Here are some dos and don'ts when it comes to taking Fasigyn.
Dos:
- If you become pregnant during the course, notify your doctor as soon as possible;
- If you get white spots in your mouth and on your tongue while or soon after finishing the course, contact your doctor or pharmacist;
- If you get itching or burning on your genitals and/or white discharge while or soon after finishing the tablets, notify your doctor. Tinidazole may contribute to yeast overgrowth;
- If you're about to start taking other medications during the course, consult your doctor beforehand;
- Notify all medical specialists that treat you about the fact you're taking tinidazole.
Don'ts
- Don't give your tablets to anyone else, even if they have similar symptoms or the same condition;
- Don't try to acquire prescription medicines without a prescription to treat any conditions.
If you miss a dose:
- Take a dose as soon as you remember, unless it is almost time for your next dose;
- Do not take more than prescribed to make up for a missed dose.
If you overdose:
- Call 911 for emergencies, or contact your doctor and/or Poison Control (U.S.: 1-800-222-1222).
Side Effects of Fasigyn
If you have any discomfort during the course, even if the symptoms aren't on the list, check with your doctor. Some reactions may be individual.
The most common adverse reactions reported with a single 2 g dose include metallic/bitter taste, nausea, weakness/fatigue/malaise, stomach upset (dyspepsia/cramps/epigastric discomfort), vomiting, anorexia, headache, dizziness, and constipation.
Skin rash or itching
If you develop a severe rash, swelling, trouble breathing, or other signs of a serious allergic reaction, stop the medicine and seek medical help right away.
Fasigyn Dose
Follow your doctor's prescription exactly. The dose depends on the condition being treated.
Tinidazole 500 mg: 4 tablets at once
A dose of 4 tablets of tinidazole 500 mg taken at once equals 2 grams (2 g). When a clinician prescribes a 2 g single dose, it means taking all four 500 mg tablets at the same time (preferably with food to reduce stomach upset).
- Trichomoniasis (adults): 2 g by mouth as a single dose with food. Treat sexual partners with the same dose at the same time.
- Giardiasis: Adults: 2 g by mouth as a single dose with food. Children (age 3 and older): 50 mg/kg as a single dose (max 2 g) with food.
- Amebiasis (intestinal): Adults: 2 g per day for 3 days with food. Children (age 3 and older): 50 mg/kg/day (max 2 g/day) for 3 days with food.
- Amebic liver abscess: Adults: 2 g per day for 3-5 days with food. Children (age 3 and older): 50 mg/kg/day (max 2 g/day) for 3-5 days with food.
- Bacterial vaginosis (non-pregnant adult women): 2 g once daily for 2 days with food, or 1 g once daily for 5 days with food.
Contraindications and Precautions
Do not take tinidazole if you have had a hypersensitivity/allergic reaction to tinidazole or other nitroimidazole derivatives.
- Pregnancy: Do not use tinidazole during the first trimester of pregnancy. If you are pregnant (especially in the 2nd/3rd trimester) or planning pregnancy, discuss risks and benefits with your doctor.
- Breast-feeding: Breastfeeding should be interrupted during tinidazole therapy and for 3 days following the last dose.
Stop tinidazole and contact a clinician promptly if abnormal neurologic signs develop (e.g., numbness/tingling, seizures).
Interaction With Other Medicinal Products and Forms of Interaction
Tell your doctor about all medicines and supplements you take.
Alcohol
Avoid alcoholic beverages and products containing ethanol or propylene glycol during tinidazole therapy and for 3 days after the last dose because a disulfiram-like reaction (flushing, abdominal cramps, nausea, vomiting, headache) may occur. Do not take tinidazole if you have taken disulfiram within the last 2 weeks.
Don't drink alcohol-containing medicine (like some cough syrups) either.
Anticoagulants
Tinidazole may enhance the effect of warfarin and other coumarin anticoagulants, resulting in a prolongation of prothrombin time/INR. The anticoagulant dose may need adjustment during tinidazole co-administration and for up to 8 days after discontinuation.
Effects on ability to drive and use machines
Tinidazole may cause dizziness or other neurologic side effects in some people. If you feel dizzy or unwell, avoid driving or operating machinery.
How to Store Fasigyn Tablets
- Store at controlled room temperature 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F).
- Protect from light and keep in the original packaging.
- Keep out of reach of children and pets.
Don't dispose of the drug by flushing it down the toilet. Ask a pharmacist about proper disposal.