Trichomoniasis

Trichomoniasis (or "trich") is caused by Trichomonas vaginalis, a tiny parasite. It is the most common curable STI worldwide — affecting an estimated 156 million people globally. Most people who have it show no symptoms, making it easy to spread unknowingly. It is highly treatable with a single dose of antibiotics.

Trichomoniasis spreads through vaginal sex and genital-to-genital contact. It infects the vagina, vulva, cervix, urethra, and sometimes the penis. It can also spread through shared sex toys.

Trichomoniasis is not spread through anal or oral sex, toilet seats, hugging, kissing, or sharing food and drinks.

About 70% of people have no symptoms. When symptoms occur (typically 5–28 days after exposure):

• Itching, burning, redness, or soreness in the genital area
• Discomfort or pain during urination or sex
• Vaginal discharge that is clear, white, yellow, or greenish — often with an unusual or fishy odor
• In people with penises: irritation or discharge from the urethra

Symptoms can come and go. Having no symptoms doesn't mean you can't pass it to partners.

Trichomoniasis requires a specific test — it is often not included in standard STI panels. Ask your provider specifically if you think you may have been exposed. Test options:

• NAAT (most sensitive) — urine sample or genital swab
• Wet prep microscopy — swab examined under microscope; less sensitive
• Rapid antigen test — available at some clinics

The CDC recommends annual testing for all sexually active people with a vagina.

Trichomoniasis is cured with antibiotics:

• For people with vaginas: Metronidazole 500mg twice daily for 7 days (recommended)
• For people with penises: Metronidazole 2g single dose
• Alternative for either: Tinidazole 2g single dose; avoid alcohol for 72 hours after

Both partners must be treated at the same time to prevent re-infection — even if one has no symptoms. Avoid sex until all partners have completed treatment and symptoms resolve. Re-infection is common: get retested 3 months after treatment if sexually active.

Prevention steps:

• Condoms reduce transmission risk — but trich can also spread in areas not covered by a condom
• Regular testing if you have multiple partners
• Mutual monogamy with a tested, uninfected partner eliminates risk
• Treat both partners to avoid the ping-pong re-infection cycle

Having trichomoniasis increases susceptibility to other STIs including HIV, so prompt treatment is important.