Green discharge from the vagina or penis is almost always a sign of infection. Normal vaginal discharge ranges from clear to white, so a green or yellow-green color signals that your body is fighting off a bacterial or parasitic invader. The most common cause is trichomoniasis, a sexually transmitted infection caused by a parasite, though gonorrhea, chlamydia, and other infections can also be responsible.
Trichomoniasis: The Most Common Cause
Trichomoniasis is a parasitic infection and the single most frequent reason for green discharge. The parasite is a tiny, mobile organism roughly the size of a white blood cell, equipped with whip-like tails that let it move through the urogenital tract. Once there, it releases proteins that actively destroy the tissue lining, which triggers the body’s immune response and produces that characteristic discharge.
The discharge from trichomoniasis is typically yellow-green, thin, frothy, and foul-smelling. It also shifts the vagina’s natural pH from a healthy range of 4.0 to 4.5 up to 5.0 or 6.0, and sometimes as high as 6.5 or more. That rising acidity disrupts the normal balance of protective bacteria, which can make symptoms worse and leave you more vulnerable to additional infections. Other common symptoms include itching, irritation, and discomfort during urination or sex.
Gonorrhea, Chlamydia, and Other STIs
Gonorrhea and chlamydia can both produce green or yellowish discharge, though they behave differently from trichomoniasis. Gonorrhea infections in women are frequently asymptomatic, meaning you may have no noticeable symptoms until the infection has already spread to the uterus and fallopian tubes, a condition called pelvic inflammatory disease. PID can cause tubal scarring that leads to infertility or ectopic pregnancy, which is why early testing matters even without obvious symptoms.
Chlamydia follows a similar pattern. When symptoms do appear, they can include unusual discharge and pain during urination, but the infection often progresses silently. If it spreads, you may develop lower abdominal pain, nausea, or fever. Both infections are diagnosed through simple swab or urine tests and treated with antibiotics.
Green Discharge in Men
Men can also develop green or yellowish discharge from the penis, usually from urethritis, which is inflammation of the urethra. The discharge may look clear and mucus-like or thick and pus-like depending on the cause. The two most established causes are gonorrhea and chlamydia, with chlamydia responsible for 15% to 40% of non-gonococcal urethritis cases. Another organism called Mycoplasma genitalium accounts for 15% to 25% of those cases in the United States.
Trichomoniasis can also cause urethritis in heterosexual men, though it tends to produce milder symptoms than in women. Other, less common causes include herpes simplex virus, Epstein-Barr virus, and certain bacteria acquired through oral or anal sex. Painful urination and itching at the tip of the penis typically accompany the discharge.
Non-Infectious Causes
A retained foreign body in the vagina, most commonly a forgotten tampon, can produce discharge that looks green or yellow and smells intensely foul. The longer the object stays in place, the worse the odor and discharge become. Symptoms include blood-stained, malodorous discharge and lower abdominal pain. In one documented case, a retained foreign body went undetected for 13 years. Once the object is removed, symptoms typically resolve quickly, though antibiotics may be needed if a secondary infection has developed.
How Green Discharge Is Diagnosed
If you visit a healthcare provider for green discharge, they’ll likely collect a swab sample. For trichomoniasis, the traditional diagnostic method involves examining the sample under a microscope, but this approach catches only about 25% of infections. A molecular test that detects the parasite’s genetic material is far more accurate, identifying roughly 92% of cases. Most clinics now use this more reliable test, especially when microscopy comes back negative but symptoms are still present.
Gonorrhea and chlamydia are also diagnosed through molecular tests, typically from a vaginal swab or urine sample. Your provider may test for multiple infections at once since co-infections are common.
Treatment and Partner Notification
Trichomoniasis is treated with a course of oral antibiotics taken twice daily for seven days in women, or as a single higher dose in men. An alternative single-dose option exists for both. Treatment is straightforward, but there’s one critical piece: all current sexual partners need to be treated at the same time, even if they have no symptoms. Without concurrent treatment, reinfection is almost guaranteed. Both you and your partners should avoid sex until treatment is complete and symptoms have fully resolved.
Gonorrhea and chlamydia are also curable with antibiotics, though they require different medications. Your provider will select the right treatment based on your test results.
Risks During Pregnancy
Green discharge during pregnancy carries additional concerns. In one study of pregnant women with abnormal discharge, 33.3% experienced preterm delivery and 33.3% had babies with low birth weight, both significantly higher rates than among women with normal discharge. Trichomoniasis in particular has been linked to premature rupture of membranes and early labor. If you’re pregnant and notice green or yellow-green discharge, getting tested and treated promptly can reduce these risks.
Symptoms That Need Urgent Attention
Green discharge on its own warrants a medical visit, but certain accompanying symptoms point to a more serious or spreading infection. These include fever or chills, pain in the pelvis or lower abdomen, nausea or vomiting, pain during sex, painful urination, and low back pain. These can indicate pelvic inflammatory disease or a systemic infection that needs treatment quickly to prevent lasting damage. Rectal bleeding, throat pain, or spotting between periods are also signs the infection may have spread beyond the genital tract.