honeypot link

Merck Manual

Please confirm that you are not located inside the Russian Federation

Quick Facts



The Manual's Editorial Staff

Last full review/revision Sep 2019| Content last modified Sep 2019
Click here for the Professional Version
Get the full details

What is trichomoniasis?

Trichomoniasis is a common sexually transmitted disease (STD). An STD is an infection that is spread from person to person by sexual contact. Trichomoniasis is more likely to cause symptoms in women than in men.

  • The most common cause is having sex with an infected partner

  • Infected women may have pain when urinating (peeing) and a lot of green or yellow liquid that comes out of the vagina (vaginal discharge)

  • Men usually have no symptoms or have mild pain when urinating and frothy discharge from the penis

  • Doctors treat trichomoniasis with antibiotics

  • To help prevent this infection, use a condom when having sex

What causes trichomoniasis?

You get trichomonas by having sex with a partner who has trichomoniasis. Your partner may not have any symptoms of trichomoniasis but can still give you the infection.

What are the symptoms of trichomoniasis?


Urinary and vaginal symptoms may occur alone or together.

  • Vaginal discharge that may be green or yellow in color, thin, look bubbly or foamy, smell fishy, and happen in large amounts

  • Itching, redness, or pain around the opening to your vagina

  • Pain or burning when you urinate (pee)

  • Feeling like you need to urinate more often


Most men have no symptoms or only mild symptoms. Even if you don't have symptoms, you can still spread the infection to your partner. If you do have symptoms, you might have:

  • Frothy discharge from your penis

  • Pain or burning when you urinate

  • Feeling like you need to urinate more than usual

How can doctors tell if I have trichomoniasis?


Your doctor will look in your vagina using a plastic speculum and take a sample of the discharge with a cotton swab. Usually your doctor will look at the sample under a microscope. Rarely your doctor will send the sample to a laboratory for testing.


Your doctor usually suspects trichomoniasis when your female sex partner was diagnosed with it. In that case, your doctor will often just give you treatment without doing any tests.

To test you for trichomoniasis, your doctor will put a small cotton swab in your penis to get a sample. Your doctor will send the sample to a laboratory for testing.

How do doctors treat trichomoniasis?

  • Doctors will give you an antibiotic (such as metronidazole or tinidazole) to take by mouth — women often only need one dose, but men may need to take the antibiotic for 5 to 7 days

  • You should not drink alcohol for at least 72 hours after you take the antibiotic — it can make you feel sick, vomit, and have a headache

  • Doctors will tell you not to have sex until your infection has gone away

Your sex partners should be checked by a doctor, who will prescribe the same antibiotic to them.

Drugs Mentioned In This Article

Generic Name Select Brand Names
NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read

Also of Interest