ConditionInfections
Trichomoniasis (Trich)
Trichomoniasis, or "trich", is a common sexually transmitted infection caused by the parasite Trichomonas vaginalis. It is the most common curable STI worldwide. About 70 percent of infected people have no symptoms. When symptoms occur, women may have frothy yellow-green vaginal discharge with a strong smell, itching and burning, and men may have urethral discharge or burning when urinating. It is easily diagnosed with a swab or urine test and cured with antibiotic tablets, but partners must be treated too.
Also called: Trich, trichomonas infection, Trichomonas vaginalis infection, TV
At a glance
- Cause
- Trichomonas vaginalis, a single-celled parasite spread through sexual contact.
- How common
- Millions of infections each year in the US; most common curable STI worldwide.
- Symptoms
- Often none; frothy, smelly yellow-green discharge, itching, burning, pain with sex or urination.
- Diagnosis
- Nucleic acid amplification test (NAAT) on a vaginal swab, urine or urethral swab.
- Treatment
- Metronidazole or tinidazole tablets; treat all sex partners; avoid sex until cured.
- Risks if untreated
- Higher HIV risk, preterm birth, pelvic inflammatory disease in some.
When to get help
Call 911 or go to the ER
- Severe lower abdominal pain with high fever, vomiting or fainting
- Heavy vaginal bleeding or severe pain in pregnancy
See a doctor within a day or two
- Lower abdominal or pelvic pain with fever, pain during sex or abnormal bleeding (possible pelvic inflammatory disease)
- Symptoms of trichomoniasis or any STI during pregnancy
- Testicle pain or swelling with urethral discharge
Book a routine appointment
- Yellow-green, frothy or foul-smelling vaginal discharge, itching or burning
- Burning on urination or discharge from the penis
- A sex partner diagnosed with trichomoniasis or another STI
- Symptoms that return after treatment
- New or multiple sex partners, for STI testing
How trichomoniasis spreads
The parasite lives in the vagina, cervix and urethra in women, and in the urethra and sometimes the prostate in men. It spreads through vaginal sex and genital contact, including between women. It is not spread by toilet seats, kissing or casual contact. Without treatment, infection can persist for months to years, especially in women.
Symptoms
Symptoms typically appear 5 to 28 days after exposure, but most infected people have none.
In women
- thin or frothy vaginal discharge, white, gray, yellow or green
- an unpleasant, often fishy smell
- itching, burning, redness or soreness of the vulva and vagina
- discomfort when urinating
- pain or discomfort during sex
- small red spots on the cervix ("strawberry cervix") seen on examination
In men
- itching or irritation inside the penis
- burning after urinating or ejaculating
- discharge from the penis
- most men have no symptoms
Trichomoniasis vs other causes of discharge
| Condition | Discharge | Other features |
|---|---|---|
| Trichomoniasis | Frothy, yellow-green, smelly | Itching, soreness; sexually transmitted |
| Bacterial vaginosis | Thin, gray-white, fishy smell | Little itching; not classed as an STI |
| Yeast infection | Thick, white, cottage-cheese-like | Intense itching, little smell |
| Chlamydia and gonorrhea | Often none, or yellow discharge | Bleeding after sex, pelvic pain |
Symptoms overlap, so testing is the only reliable way to tell them apart.
Diagnosis
- NAAT (nucleic acid amplification test): the most accurate test, done on a vaginal swab (which can be self-collected), urine, or a urethral swab in men.
- Rapid antigen tests in some clinics.
- Microscopy (wet mount): quick but misses many infections.
Anyone diagnosed with trichomoniasis should be tested for other STIs, including chlamydia, gonorrhea, syphilis and HIV.
Treatment
- Antibiotic tablets: metronidazole, or tinidazole, prescribed by a clinician. CDC guidelines recommend a 7-day course of metronidazole for women and a single larger dose for men. Take every dose.
- Treat all recent sex partners, even if they have no symptoms, to prevent reinfection. Expedited partner therapy (giving treatment for partners) is allowed in many US states.
- Avoid sex until you and your partners have completed treatment and symptoms have gone, typically about 7 days.
- Retest: women should be retested within about 3 months, because reinfection is common.
- Pregnancy: treatment is recommended and safe in all trimesters.
Over-the-counter treatments for yeast infections do not cure trichomoniasis.
Complications
- Increased risk of getting and passing on HIV
- Pregnancy complications: preterm birth and low birth weight
- Pelvic inflammatory disease, especially in women with HIV
- Persistent or recurrent infection
- In men, rarely, prostate or epididymis inflammation
Prevention
- Use condoms consistently and correctly.
- Limit the number of sex partners and get tested with new partners.
- Do not douche, which can disturb vaginal bacteria.
- Get tested regularly if you have new or multiple partners, and annually if you are a woman living with HIV.
Frequently asked questions
What are the symptoms of trichomoniasis?
Most people have no symptoms. Women may have frothy, yellow-green, smelly vaginal discharge, itching, burning, soreness and pain during sex or urination. Men may notice burning after urinating or ejaculating, or discharge from the penis.
How is trichomoniasis treated?
It is treated with prescribed antibiotic tablets, usually metronidazole or tinidazole. All sex partners must also be treated, and you should avoid sex until everyone has finished treatment and symptoms have resolved. Women should be retested within 3 months.
Can men get trichomoniasis?
Yes. Men can carry and spread trichomoniasis, usually without symptoms. Some notice itching inside the penis, burning after urinating or ejaculating, or discharge. Men whose partners are diagnosed should be treated even if they feel well.
Can trichomoniasis go away on its own?
In men, it sometimes clears on its own within weeks, but in women it often persists for months or years without treatment. Because it is easily cured and can cause complications and spread to partners, treatment is always recommended.
How long after treatment can I have sex?
Wait until you and all your partners have completed treatment and any symptoms have resolved, usually about 7 days after starting a 7-day course or after a single-dose treatment. Having sex earlier risks reinfection.
Sources
This guide was written from current patient and clinical guidance, including:
- CDC: Sexually Transmitted Infections Treatment Guidelines, trichomoniasis
- CDC: About trichomoniasis
- American College of Obstetricians and Gynecologists: Vaginitis FAQ
- MedlinePlus: Trichomoniasis
- World Health Organization: Sexually transmitted infections fact sheet