Font Size

Antiprotozoals for Trichomoniasis


Generic NameBrand Name
metronidazoleFlagyl, Tindamax
tinidazoleFlagyl, Tindamax

How It Works

Antiprotozoals kill the tiny parasite (a one-celled protozoan organism) that causes trichomoniasis (trich).

Why It Is Used

These medicines are used to cure trichomoniasis by destroying the parasite that causes the condition.

Oral metronidazole can be taken either as a single dose or as multiple doses. A single oral dose of metronidazole can be taken by a pregnant woman if needed.1 Women who are breast-feeding will be instructed by their doctors on the use of metronidazole.

The treatment regimen with tinidazole is usually a one-time dose. Pregnant women should not take tinidazole, because it is not yet clear whether this medicine is safe to use during pregnancy.

How Well It Works

The cure rate in treating trichomoniasis using metronidazole is 90% to 95%.1

The cure rate using tinidazole is 86% to 100%.1

Sex partners should be treated at the same time. Sexual intercourse should be avoided until symptoms are gone. Men may not have any symptoms but still need treatment.

People who are infected with HIV receive the same treatment for trich as those who are HIV-negative.


  • No follow-up is needed if symptoms go away.
  • If symptoms do not go away, you may need to take the medicine again.
  • If treatment fails after this and you have not been reinfected, further testing may be done to find out the cause of your symptoms. It is possible to have a strain of trich that is resistant to metronidazole. High-dose tinidazole is used for metronidazole-resistant trich organisms and is as effective as metronidazole in curing trich.2

Metronidazole vaginal suppositories or creams are not recommended, because oral metronidazole is much more effective. Vaginal medicines cure trich in less than 50% of cases. Metronidazole vaginal gel, which is used to treat bacterial vaginosis, is not recommended by the U.S. Centers for Disease Control and Prevention (CDC) for treatment of trich.1

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call or other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.

Call your doctor right away if you have:

  • Hives.
  • Numbness, tingling, pain, or weakness in your hands or feet.

Common side effects of these antibiotics include:

  • Diarrhea.
  • Dizziness.
  • Headache.
  • Tiredness.
  • Trouble sleeping.
  • Mild stomach pain or cramps, nausea, loss of appetite.
  • Metallic or unpleasant taste in the mouth.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

The oral form of these medicines is the most effective treatment for trichomoniasis.

Oral metronidazole can be taken by pregnant women at any time during pregnancy.

While you are taking these medicines and for at least 3 days after your last dose, do not use alcohol or products that contain alcohol.

Trich during pregnancy raises the risk of premature rupture of membranes (PROM) and premature delivery. Treating the infection does not appear to reduce this risk.2 If you are pregnant and have trich, talk to your doctor about the pros and cons of treatment.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)Click here to view a form.(What is a PDF document?) to help you understand this medication.



  1. Centers for Disease Control and Prevention (2010). Trichomoniasis section of Sexually transmitted diseases treatment guidelines 2010. MMWR, 59(RR-12): 58–61. Also available online:

  2. American College of Obstetricians and Gynecologists (2006, reaffirmed 2011). Vaginitis. ACOG Practice Bulletin No. 72. Obstetrics and Gynecology, 107(5): 1195–1206.


ByHealthwise Staff
Primary Medical ReviewerSarah Marshall, MD - Family Medicine
Specialist Medical ReviewerJeanne Marrazzo, MD, MPH - Infectious Disease
Last RevisedJuly 9, 2012

eMedicineHealth Medical Reference from Healthwise

This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

To learn more visit

© 1995-2014 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.

Medical Dictionary