Green vaginal discharge almost always signals an infection. Normal discharge ranges from clear to white and has little to no odor, so a shift to green, especially with a strong smell or unusual texture, means your body is actively fighting something off. The most common culprits are trichomoniasis, gonorrhea, chlamydia, and bacterial vaginosis.
Why Discharge Turns Green
The green color comes from your immune system doing its job. When your body detects an infection in the vaginal area, it sends large numbers of white blood cells to the site. These cells contain an enzyme called myeloperoxidase, which produces powerful germ-killing compounds. That enzyme has a green pigment. The more white blood cells that accumulate, the greener the discharge becomes. It’s the same reason infected mucus from a sinus infection turns green.
A healthy vagina maintains a slightly acidic environment, with a pH between 3.8 and 4.5. Infections disrupt that balance, allowing harmful bacteria or parasites to multiply and triggering the inflammatory response that produces colored discharge.
Trichomoniasis
Trichomoniasis, often called “trich,” is one of the most recognizable causes of green discharge. It’s a sexually transmitted infection caused by a parasite, and it produces discharge that is thin, frothy or bubbly, and ranges from clear to yellow-green. The hallmark feature is a strong fishy odor.
Many people with trich also experience itching, burning during urination, and redness or soreness around the vaginal area. However, a significant number of infected people have mild symptoms or none at all, which means the infection can go undetected and be passed to partners. Trich is treated with a course of oral antibiotics, typically taken twice daily for seven days. Sexual partners need treatment at the same time to prevent reinfection.
Gonorrhea and Chlamydia
Both gonorrhea and chlamydia can produce cloudy, yellow, or green discharge. These bacterial STIs often occur together and share overlapping symptoms, including pain during urination, bleeding between periods, and pelvic discomfort. The discharge from gonorrhea tends to be thicker and more pus-like compared to the thinner discharge seen with trichomoniasis.
Chlamydia is particularly tricky because it frequently causes no noticeable symptoms at all, especially in the early stages. When discharge does appear, it may be subtle enough to dismiss. Left untreated, both infections can spread to the uterus and fallopian tubes, leading to pelvic inflammatory disease, chronic pain, and fertility problems. Both are curable with antibiotics, but the specific treatment differs from what’s used for trich, which is why getting a proper diagnosis matters.
Bacterial Vaginosis
Bacterial vaginosis (BV) is not an STI, but it can produce discharge that looks similar. BV happens when the balance of bacteria in the vagina tips in favor of harmful strains. The discharge is typically thin and may appear gray, yellow-green, or off-white. Like trichomoniasis, it often comes with a fishy odor that may be stronger after sex.
BV is the most common vaginal infection in women of reproductive age, and it can develop from things like douching, using scented products near the vagina, or having new or multiple sexual partners. It’s treated with prescription antibiotics, either taken orally or applied as a vaginal gel. BV has a tendency to come back, so paying attention to recurring symptoms is important.
How Doctors Identify the Cause
You can’t reliably tell the difference between these infections based on discharge alone. Color and texture overlap too much between conditions. Diagnosis requires lab testing, and the accuracy of that testing varies significantly by method.
Traditional clinical examination under a microscope catches only 58% to 77% of infections depending on the type. Nucleic acid amplification testing (NAAT), a more advanced lab method, detects 97% of the common vaginal pathogens. If your provider offers a swab test, NAAT-based panels give the most reliable results. A single swab can check for trichomoniasis, BV, gonorrhea, and chlamydia simultaneously, which means you get a clear answer rather than a guess based on appearance.
Green Discharge During Pregnancy
Green discharge during pregnancy deserves prompt attention. Vaginal infections that cause colored discharge can trigger inflammation that weakens the membranes surrounding the baby, increasing the risk of premature rupture and preterm labor. Preterm delivery carries serious risks for the newborn, particularly related to lung, brain, and digestive system development.
Infections that seem minor outside of pregnancy become higher-stakes during it. Trichomoniasis, BV, and other vaginal infections have all been linked to preterm birth when left untreated. The good news is that these infections are treatable during pregnancy, and early treatment reduces the risk of complications. If you’re pregnant and notice a change in discharge color or smell, getting tested sooner rather than later gives you the best outcome.
Symptoms That Need Quick Attention
Green discharge on its own warrants a medical visit, but certain accompanying symptoms suggest the infection may be spreading or worsening. Watch for fever, sharp or worsening pelvic pain, pain during sex, heavy or unusual vaginal bleeding, and nausea or vomiting. These can point to pelvic inflammatory disease or another complication that needs more aggressive treatment. Pain in the lower abdomen combined with green discharge is a particularly important combination not to ignore.