Green vaginal discharge almost always signals an infection or irritation that needs attention. Normal discharge ranges from clear to white or slightly off-white, so a shift to green or yellow-green typically means your body is fighting something off. The most common culprit is trichomoniasis, a sexually transmitted infection caused by a parasite, though other infections and even a forgotten tampon can produce the same color change.
Trichomoniasis: The Most Common Cause
Trichomoniasis is a parasitic infection and one of the most frequently diagnosed STIs worldwide. The discharge it produces is often thin or frothy, yellow-green in color, and has a noticeably foul or fishy smell. Along with the discharge itself, you may experience itching, vulvar irritation, pain during urination, discomfort during sex, or lower abdominal pain.
One tricky thing about trichomoniasis is that 20 to 50 percent of women who have it show no symptoms at all. That means you could carry the infection without realizing it, which is why testing matters even when symptoms are mild or inconsistent. The infection also shifts your vaginal pH significantly. A healthy vagina sits around 3.8 to 4.5 on the pH scale (moderately acidic), but trichomoniasis can push that above 5.4, sometimes as high as 6.5 or more. That shift in acidity is part of why the discharge looks and smells so different from normal.
Treatment is straightforward: an oral antibiotic taken for about a week. Sexual partners need to be treated at the same time, because reinfection from an untreated partner is the most common reason the infection comes back. Most people clear the infection completely with one course of treatment.
Gonorrhea and Chlamydia
Gonorrhea can also cause green discharge, particularly in men, where white, yellow, or green discharge from the penis is a hallmark symptom. In women, gonorrhea more commonly produces white or yellow discharge along with pelvic pain, painful urination, and bleeding between periods. These two infections frequently occur together, so if you’re tested for one, expect to be tested for the other as well.
Many people with chlamydia or gonorrhea have no obvious symptoms, especially early on. When green discharge appears alongside pelvic pain or burning during urination, getting tested for both infections is the logical next step. Left untreated, either can progress to pelvic inflammatory disease, which can damage the reproductive organs and affect fertility.
Bacterial Vaginosis
Bacterial vaginosis (BV) happens when the natural balance of bacteria in the vagina shifts, with harmful bacteria outgrowing the beneficial ones. The discharge from BV is more commonly grayish-white, but it can sometimes appear greenish, especially when mixed with other fluids. The telltale sign is a strong fishy odor, particularly after sex. BV pushes vaginal pH above 4.5, similar to other infections, and is diagnosed when certain criteria are met, including the presence of “clue cells” visible under a microscope.
BV is not sexually transmitted, though sexual activity can increase your risk. It’s the most common vaginal infection in women of reproductive age, and while it sometimes resolves on its own, treatment with antibiotics prevents complications.
A Forgotten Tampon or Retained Object
It happens more often than you might think. A tampon left in too long, or any small object retained in the vaginal canal, can cause discharge that turns yellow, green, pink, gray, or brown. The smell is usually the first thing you notice: strong and unmistakably unpleasant. Other signs include vaginal swelling or redness, pelvic pain, discomfort while urinating, and sometimes a fever.
Tampons should be changed every 4 to 6 hours, and manufacturers recommend never leaving one in for more than 8 hours. If you suspect a retained tampon, removal and a brief medical evaluation are usually all that’s needed, though antibiotics may be prescribed if infection has developed.
What Testing Looks Like
Diagnosing the cause of green discharge is usually quick. A clinician collects a small sample of the discharge and examines it under a microscope. For trichomoniasis, the parasites are visible as tiny, moving organisms with whip-like tails on an unstained slide. This examination needs to happen within about 10 minutes of collecting the sample for the best accuracy. For bacterial vaginosis, the microscope reveals clue cells (vaginal cells coated in bacteria) and a distinct shift in the types of bacteria present.
Your vaginal pH may also be checked with a simple test strip. A reading at or below 4.5 generally rules out infection, while anything above that number points toward BV, trichomoniasis, or another condition. STI testing through swabs or urine samples can confirm or rule out gonorrhea and chlamydia.
Risks During Pregnancy
Green discharge during pregnancy deserves prompt attention. Infections that cause abnormal discharge are linked to a range of serious complications. Research comparing pregnant women with pathological discharge to those with normal discharge found significantly higher rates of premature membrane rupture, preterm delivery, and miscarriage. Newborns were also affected: low birth weight, low Apgar scores (a measure of a baby’s health right after birth), respiratory distress, and neonatal intensive care admissions were all more common.
Trichomoniasis specifically has been associated with premature rupture of membranes, preterm delivery, and low birth weight. The good news is that these infections are treatable during pregnancy, and early treatment reduces the risk of these outcomes considerably. If you’re pregnant and notice a change in discharge color, getting tested sooner rather than later makes a real difference.
Green vs. Yellow vs. White Discharge
Color alone doesn’t give you a definitive diagnosis, but it narrows the possibilities. Here’s a general guide:
- Clear to white: Typically normal. Consistency changes throughout your cycle.
- Thick, white, cottage cheese-like: Often a yeast infection. Usually comes with itching but not a strong odor.
- Grayish-white with a fishy smell: Most commonly bacterial vaginosis.
- Yellow to yellow-green, thin or frothy, foul-smelling: Strongly suggestive of trichomoniasis.
- Green or yellow with pelvic pain: Could indicate gonorrhea, especially with painful urination or bleeding between periods.
Smell and texture matter as much as color. A frothy consistency with a foul odor points toward trichomoniasis, while a thicker discharge without much smell leans more toward a yeast infection. When in doubt, the only way to know for certain is through testing.