Green vaginal discharge almost always signals an infection. Healthy discharge ranges from clear to white to slightly yellow depending on where you are in your menstrual cycle, but green falls outside that normal spectrum. The shade can range from yellow-green to bright green, and it’s typically accompanied by other symptoms like a strong odor, itching, or irritation.
Why Discharge Turns Green
The green color comes from your immune system doing its job. When your body detects an infection, it sends large numbers of white blood cells to fight it off. These immune cells contain a greenish-tinted enzyme, and when they accumulate in vaginal fluid, the discharge shifts from its usual clear or white to yellow-green or green. The more intense the immune response, the greener the discharge tends to be.
This is the same reason infected wounds produce greenish pus and why nasal mucus turns green during a sinus infection. The color itself isn’t dangerous, but it reliably points to an active infection that needs treatment.
What Normal Discharge Looks Like
For comparison, discharge changes naturally throughout your menstrual cycle. In the days after your period, it’s typically dry or sticky and white or light yellow. Mid-cycle, it becomes creamy and white, like yogurt. Around ovulation (roughly days 10 to 14), it turns clear, slippery, and stretchy, resembling raw egg whites. Throughout all of these phases, healthy discharge is generally odorless. Green, gray, or discharge with a strong fishy or foul smell doesn’t fit any stage of a normal cycle.
Trichomoniasis
Trichomoniasis is one of the most common causes of green discharge. It’s a sexually transmitted infection caused by a parasite, and it produces a thin, yellow-green discharge that often has a noticeable fishy smell. The volume of discharge may increase noticeably, and you might also experience itching, burning, or redness around the vulva.
Many people with trichomoniasis have mild symptoms or none at all, which means it can go undetected for weeks or months. When symptoms do appear, the greenish discharge and fishy odor are the most recognizable signs. Treatment is a course of oral antibiotics taken over seven days, and sexual partners need to be treated at the same time to prevent reinfection.
Gonorrhea and Chlamydia
Both gonorrhea and chlamydia can produce cloudy, yellow, or green vaginal discharge. These bacterial STIs often occur together, and both can be present with minimal symptoms, which makes them easy to miss without testing. Beyond unusual discharge, you might notice painful urination or bleeding between periods.
Left untreated, these infections can spread from the cervix into the uterus and fallopian tubes, causing pelvic inflammatory disease (PID). PID symptoms include lower abdominal pain, fever, foul-smelling discharge, pain during sex, and bleeding between periods. PID can lead to long-term complications including chronic pelvic pain and fertility problems, so early treatment matters.
Bacterial Vaginosis
Bacterial vaginosis (BV) is not a sexually transmitted infection, but it can produce a thin, yellow-green or gray discharge with a fishy odor. BV happens when the normal balance of bacteria in the vagina shifts, allowing certain types to overgrow. It’s the most common vaginal condition in women of reproductive age.
BV and STIs have a two-way relationship: having a current STI raises the risk of developing BV, and having BV makes you more vulnerable to picking up an STI. The discharge from BV can look very similar to what trichomoniasis produces, so testing is the only reliable way to tell them apart. BV is treated with oral or topical antibiotics.
Retained Tampon or Foreign Object
A forgotten tampon is a surprisingly common and often overlooked cause of green or otherwise unusual discharge. The discharge can be yellow, green, pink, gray, or brown, and it’s usually accompanied by a strong, foul smell that gets worse over time. If you notice a sudden onset of bad-smelling discharge and can’t identify another cause, it’s worth considering whether a tampon, contraceptive sponge, or other object may have been left in place. A healthcare provider can quickly check for and remove it, and symptoms typically resolve within a day or two.
How the Cause Is Identified
A healthcare provider can often narrow down the cause during a single office visit. The first step is usually checking the pH of your vaginal fluid. Normal vaginal pH sits at 4.5 or below; a reading above 4.5 suggests BV or trichomoniasis, though trichomoniasis can sometimes occur with normal pH.
A small sample of discharge is examined under a microscope. In one preparation, the provider looks for moving parasites (trichomoniasis) or “clue cells,” which are vaginal cells coated in bacteria characteristic of BV. A second preparation helps identify yeast infections. However, microscopy catches only about 50% of trichomoniasis cases, so if the initial exam is negative but symptoms point toward an infection, a more sensitive molecular test (similar to a COVID PCR test) can detect the parasite with much greater accuracy. Gonorrhea and chlamydia are diagnosed through swab or urine tests sent to a lab.
Green Discharge During Pregnancy
Green discharge during pregnancy deserves prompt attention because the infections behind it carry specific risks for the baby. Untreated chlamydia has been associated with preterm delivery, low birth weight, and can cause eye infections or pneumonia in the newborn. Gonorrhea can be transmitted during delivery, potentially causing blindness, joint infections, or blood infections in the baby. Trichomoniasis during pregnancy raises the risk of early delivery and low birth weight (under 5.5 pounds).
All of these infections are treatable during pregnancy with antibiotics that are safe for the baby. The key is catching them early, which is why any green or unusually colored discharge during pregnancy warrants a visit to your provider rather than a wait-and-see approach.
What to Watch For
Green discharge on its own is reason enough to get tested, but certain combinations of symptoms suggest a more urgent situation. Lower abdominal pain paired with green discharge and fever may indicate that an infection has spread beyond the vagina into the reproductive organs. Pain or bleeding during sex, painful urination, and bleeding between periods are additional signs that something more than a simple vaginal infection is going on. The sooner these infections are identified, the simpler and more effective treatment tends to be.