Green discharge is almost always a sign that your body is actively fighting an infection. The green color comes from a specific enzyme inside white blood cells called myeloperoxidase, which is so distinctly green that scientists originally named it “verdoperoxidase” (from the Latin word for green). When your immune system sends large numbers of these cells to fight off bacteria or parasites, the resulting discharge takes on that greenish tint. So green discharge isn’t the infection itself. It’s visible evidence of your immune response working overtime.
Several conditions can trigger this response, ranging from sexually transmitted infections to something as simple as a forgotten tampon. The cause matters, because treatment differs significantly depending on what’s behind it.
Trichomoniasis: The Most Common Culprit
Trichomoniasis is a parasitic sexually transmitted infection and one of the most frequent causes of green or yellow-green discharge. The World Health Organization estimated roughly 156 million new cases globally in 2020 alone, making it far more common than most people realize. It’s caused by a microscopic parasite that infects the vagina or urethra.
In women, the hallmark symptom is a frothy, greenish discharge that often has a strong, unpleasant odor. You may also notice itching, soreness, redness around the vagina, pain during urination, or discomfort during sex. The discharge can range from yellowish to distinctly green, and the volume is often noticeably heavier than normal.
Many people with trichomoniasis have no symptoms at all, which is part of why it spreads so easily. When symptoms do appear, they typically develop within 5 to 28 days of exposure. The infection is curable with a course of oral antibiotics, and sexual partners need treatment at the same time to prevent reinfection.
Gonorrhea and Chlamydia
Both gonorrhea and chlamydia can produce abnormal discharge, though they more commonly cause yellow discharge rather than green. The American College of Obstetricians and Gynecologists lists yellow vaginal discharge as the most common symptom of both infections. That said, when the immune response is strong enough, discharge from either infection can shade into green territory, particularly with gonorrhea.
Other shared symptoms include bleeding between periods or after sex, painful urination, and rectal pain or discharge if the infection has spread to the rectum. The tricky part is that both infections are frequently silent. Many women and a significant number of men experience no symptoms at all, which is why routine screening matters if you’re sexually active with new or multiple partners.
Left untreated, both infections can lead to serious complications. In women, the bacteria can travel upward and cause pelvic inflammatory disease, which can damage the fallopian tubes and lead to infertility. In men, untreated gonorrhea or chlamydia can cause painful inflammation in the testicles and, in some cases, also affect fertility.
Bacterial Vaginosis
Bacterial vaginosis (BV) is not a sexually transmitted infection, but it’s one of the most common vaginal conditions in women of reproductive age. It happens when the balance of bacteria in the vagina shifts, allowing certain types to overgrow. The Mayo Clinic notes that BV discharge can be thin and gray, white, or green, often accompanied by a noticeable “fishy” odor that tends to get stronger after sex.
BV differs from STIs in an important way: it’s a disruption of your vaginal ecosystem rather than an invasion by an outside organism. Things like douching, new sexual partners, or using scented products near the vagina can shift the bacterial balance. While BV sometimes resolves on its own, it often requires treatment, especially during pregnancy, where it’s been linked to preterm labor, premature rupture of membranes, and postpartum infections.
Foreign Objects in the Vagina
A surprisingly common and often overlooked cause of green discharge is a retained foreign object. The most frequent culprit is a tampon that was inserted and forgotten, but other possibilities include broken pieces of a condom, objects used during sex, vaginal pessaries that haven’t been cleaned regularly, or even small bits of toilet paper (particularly in children).
When something remains in the vaginal canal longer than it should, bacteria colonize it rapidly. Your body mounts an immune response, producing discharge that’s typically greenish-yellow or brown, with a distinctly foul smell. The odor is usually the most noticeable symptom, and it can be quite strong. Removal of the object and sometimes a short course of antibiotics resolves the problem quickly.
Green Discharge in Men
Men can also develop green or greenish discharge, typically from the urethra. The most common causes are the same STIs: gonorrhea, chlamydia, and trichomoniasis. Discharge may appear cloudy, yellowish, or green, and it often shows up as a stain on underwear or a visible drop at the tip of the penis.
Other symptoms in men include burning during urination, increased urinary frequency, and swelling or tenderness in the testicles. Non-infectious causes exist too, including irritation from spermicides, soaps, or physical pressure on the urethra from activities like cycling. Without treatment, urethral infections in men can lead to complications including epididymitis (painful swelling behind the testicle), prostate infections, scarring of the urethra, and in some cases infertility.
Why It Matters During Pregnancy
Green discharge during pregnancy deserves prompt attention. The infections behind it, particularly BV and trichomoniasis, carry real risks for both the pregnancy and the baby. BV during pregnancy has been associated with spontaneous abortion, preterm labor, premature rupture of membranes, infection of the amniotic fluid, and postpartum uterine infections.
The mechanism is well understood: the infection triggers your body to produce inflammatory compounds that stimulate the release of prostaglandins, hormone-like substances that cause uterine contractions. These contractions can initiate premature labor. Preterm birth remains one of the leading causes of complications in newborns, so catching and treating these infections early in pregnancy has a meaningful impact on outcomes. Most of the standard treatments are safe during pregnancy, though your provider will choose the appropriate option based on how far along you are.
How the Cause Gets Diagnosed
Figuring out what’s behind green discharge usually involves a combination of a physical exam and lab testing. In the office, a clinician can check the vaginal pH and examine a sample of the discharge under a microscope, looking for the motile parasites of trichomoniasis or the “clue cells” that indicate BV (normal cells coated in a distinctive layer of bacteria).
Microscopy alone, however, catches only about half of trichomoniasis cases. For more reliable results, nucleic acid amplification tests (NAATs) are considered the gold standard. These are the same type of highly sensitive tests used for chlamydia and gonorrhea screening, and they can be run on vaginal swabs or urine samples. If you’re being tested for one STI, it’s worth testing for the others at the same time, since co-infections are common.
What Treatment Looks Like
Treatment depends entirely on the cause, which is why getting tested matters more than guessing based on symptoms alone.
- Trichomoniasis is treated with oral antibiotics, typically taken twice daily for seven days in women. Men are often prescribed a single, larger dose. Sexual partners need simultaneous treatment, and you should avoid sex until both partners have completed the full course.
- Gonorrhea and chlamydia each require specific antibiotic regimens. Because gonorrhea has developed resistance to many antibiotics over the years, current treatment protocols are more targeted than they used to be. Both infections are curable, and retesting a few months after treatment is recommended to make sure you haven’t been reinfected.
- Bacterial vaginosis is treated with antibiotics as well, either oral or vaginal. Recurrence is common, with many women experiencing repeat episodes within a year.
- Foreign objects require removal, which is usually quick and straightforward. If infection has set in, a short antibiotic course follows.
Green discharge is your body sending a clear signal that something needs attention. The good news is that every common cause is treatable, and most resolve completely with the right course of antibiotics. The key step is getting tested so treatment targets the actual problem.