Green vaginal or penile discharge almost always signals an infection that needs treatment. It is not a normal variation of healthy discharge, which typically ranges from clear to white. The most common cause is trichomoniasis, a sexually transmitted infection caused by a parasite, though other infections can also be responsible.
Why Discharge Turns Green
Healthy vaginal discharge exists to keep the vagina clean and lubricated. It ranges from clear to milky white and has a mild or no odor. Its acidity, typically between a pH of 3.8 and 4.5, helps keep harmful organisms in check. When an infection takes hold, the body’s immune response and the organisms themselves change the color, texture, and smell of that discharge. Green or yellow-green coloring is a strong indicator that something infectious is going on.
In men, any visible discharge from the penis (outside of urine or semen) is considered abnormal. Green or yellow discharge in men points to the same set of infections and warrants the same urgency.
Trichomoniasis: The Most Common Cause
Trichomoniasis, often called “trich,” is the infection most closely linked to green discharge. It’s caused by a tiny parasite called Trichomonas vaginalis and is one of the most common sexually transmitted infections worldwide. The CDC describes the discharge as thin, increased in volume, and ranging from clear to yellowish or greenish, often with a fishy or musty smell. The discharge may also appear frothy or bubbly, which is a fairly distinctive clue.
Beyond the discharge itself, trichomoniasis can cause genital itching and soreness, a burning sensation when you pee, and discomfort during sex. But many people with trich have no symptoms at all, which is part of why it spreads so easily. It’s transmitted through unprotected vaginal sex and shared sex toys. Men with trich may notice a yellow or green discharge from the penis, along with irritation and burning during urination.
Other Infections to Rule Out
While trichomoniasis is the textbook cause of green discharge, your provider will also want to rule out a few other possibilities.
Gonorrhea can produce cloudy, discolored discharge, though it often causes no symptoms at all. Chlamydia similarly may present with unusual discharge but frequently goes unnoticed. Both are bacterial STIs that require different treatment than trichomoniasis, so accurate testing matters.
A less well-known condition called desquamative inflammatory vaginitis (DIV) can also produce yellow to greenish-yellow discharge. DIV is not sexually transmitted. It’s an inflammatory condition of the vaginal lining that causes irritation, discharge, and discomfort, and it tends to affect people during or after menopause.
Bacterial vaginosis, while more commonly associated with gray or white discharge, can sometimes produce discharge with a greenish tint, particularly when it occurs alongside another infection.
What Testing Looks Like
If you go in with green discharge, the visit is usually straightforward. For vaginal testing, a swab of the vaginal wall is the preferred method. The gold standard for detecting STIs like chlamydia and gonorrhea is a type of lab test called a nucleic acid amplification test, or NAAT. These tests are highly accurate, with sensitivity above 95% and specificity above 99%, meaning false results are rare.
Your provider may also check vaginal pH and examine the discharge under a microscope. A pH above 4.5 can indicate an infection like trichomoniasis or bacterial vaginosis, since healthy vaginal pH sits between 3.8 and 4.5. For trich specifically, the parasite can sometimes be spotted directly on a microscope slide, though lab-based testing is more reliable.
Results for NAATs typically come back within a few days. If trichomoniasis is confirmed, treatment is a course of oral antibiotics, usually taken twice daily for seven days. An alternative is a single, larger dose of a related medication. Sexual partners need to be treated at the same time to prevent reinfection.
Risks of Leaving It Untreated
Green discharge is not something to wait out. Untreated trichomoniasis increases the risk of pelvic inflammatory disease, a serious infection of the uterus, fallopian tubes, or ovaries that can lead to chronic pain and fertility problems. The World Health Organization also links untreated trich to poor birth outcomes in pregnant people.
During pregnancy, the stakes are higher. Vaginal infections that cause inflammation can trigger the early release of compounds that stimulate uterine contractions, potentially leading to premature rupture of membranes and preterm labor. Preterm birth carries significant risks for the baby, including underdeveloped lungs, brain, and digestive system. Bacterial vaginosis during pregnancy has been associated with spontaneous abortion, infection of the placenta, and postpartum complications like uterine infection.
Untreated STIs also increase susceptibility to HIV, making prompt treatment important for broader sexual health.
Signs That Need Prompt Attention
Any green discharge warrants a medical visit, but certain combinations of symptoms suggest a more urgent situation. These include:
- Pelvic pain or lower abdominal pain, which may indicate the infection has spread beyond the vagina
- Fever, suggesting a more systemic response
- Frothy or cottage cheese-like texture, pointing toward active infection
- Bleeding between periods or after sex
- Strong, foul odor that is noticeably different from your normal scent
- Burning during urination, which often accompanies STIs
If you’re pregnant and notice green discharge, getting tested quickly is especially important given the risks to the pregnancy. Most infections that cause green discharge are fully treatable with a short course of medication, and symptoms typically improve within days of starting treatment.