Green discharge is almost always a sign of infection. The green color comes from white blood cells rushing to fight off a pathogen. These immune cells release a green-tinted enzyme as they work, and the more of them that accumulate, the more distinctly green the discharge becomes. While several infections can cause this, the most common culprit is trichomoniasis, a sexually transmitted infection caused by a parasite.
Trichomoniasis: The Most Likely Cause
Trichomoniasis is the infection most closely associated with green discharge. It produces a green-yellow, frothy discharge that often has a fishy smell. The CDC describes the discharge as thin or increased in volume, and it can range from yellowish to distinctly green. Beyond the discharge itself, you may notice genital itching and soreness, pain or burning when you pee, and general irritation around the vulva or vaginal opening.
Trichomoniasis is caused by a tiny parasite called Trichomonas vaginalis, spread through sexual contact. It affects both women and men, though symptoms differ. Men with trichomoniasis can develop a yellow or green discharge from the penis along with burning during urination, though many men have no symptoms at all. Women are more likely to be symptomatic, but even among women, some infections are silent.
Untreated trichomoniasis carries real risks. It’s linked to a 1.5 times increased risk of acquiring HIV if exposed. During pregnancy, it can lead to preterm delivery, low birth weight, and premature rupture of membranes. In rare cases, the parasite can even pass to a newborn during delivery, causing vaginal or respiratory infections in the baby.
Other Infections That Cause Green Discharge
Gonorrhea is another STI that can produce green or yellow-green discharge in both men and women. In women, it may be accompanied by bleeding between periods and pelvic pain. In men, gonorrhea typically causes a thick green or yellow discharge from the penis along with painful urination. Chlamydia, while more commonly associated with clear or white discharge, can occasionally produce a greenish tint as the immune response intensifies.
Bacterial vaginosis (BV) is sometimes confused with trichomoniasis because both can produce a fishy odor. However, BV typically causes a thin, milky-white or grayish discharge rather than green. If your discharge is clearly green and frothy, trichomoniasis is a more likely explanation than BV.
Green Discharge in Children
In young children, green vaginal discharge has a different set of causes. The most common is vulvovaginitis, an irritation of the vulva and vagina. Irritants account for up to 75% of cases in toddlers, including harsh soaps, bubble baths, scented lotions, and tight-fitting clothing.
Foreign objects are another important cause. Children sometimes place small items inside their vaginas while exploring their bodies. Toilet paper is the most common object found, but small toys are also frequently the culprit. A foreign object left in place will cause discharge that can turn green or yellow-green and develop a strong odor. Poor wiping habits can also introduce fecal bacteria, leading to infection and discolored discharge.
Why the Color Matters
Normal vaginal discharge is clear to white, sometimes slightly yellow when it dries. It changes in consistency throughout the menstrual cycle but stays within that color range. Green is never part of the normal spectrum. The green tint specifically signals that your immune system is actively fighting something, because the enzyme released by white blood cells during that fight is what creates the color. This is the same reason nasal mucus turns green during a sinus infection.
The shade and texture offer additional clues. Frothy, green-yellow discharge with a fishy smell points strongly toward trichomoniasis. Thick, opaque green or yellow-green discharge is more suggestive of gonorrhea. A faint greenish tinge with mild irritation could indicate a less severe bacterial infection. Regardless of the shade, green discharge warrants testing.
How It Gets Diagnosed
If you go in with green discharge, your provider will likely test for trichomoniasis and other STIs. The traditional approach, examining a sample under a microscope (called a wet mount), only catches trichomoniasis 44% to 68% of the time. Molecular tests, which detect the parasite’s genetic material, are far more accurate, with sensitivity above 95% and specificity above 99% in most cases. Some clinics also offer rapid tests that return results in 10 to 15 minutes with good accuracy.
If you’re tested for trichomoniasis with a microscope slide and the result is negative, it’s worth asking about molecular testing. A negative wet mount misses roughly one-third to one-half of infections. Testing for gonorrhea and chlamydia is typically done at the same time using a urine sample or swab.
What Treatment Looks Like
Trichomoniasis is treated with a course of oral antibiotics. The infection is fully curable, and symptoms usually resolve within a week of starting treatment. Sexual partners need to be treated at the same time, even if they have no symptoms, to prevent reinfection. You’ll be advised to avoid sex until both you and your partner have finished treatment and symptoms have cleared.
Gonorrhea requires a different antibiotic regimen but is also curable. If both infections are present, they can be treated simultaneously. The key is getting tested rather than guessing, because the correct treatment depends entirely on which organism is causing the problem.