Yellow-green vaginal discharge usually signals an infection, most commonly trichomoniasis, a sexually transmitted infection caused by a tiny parasite. It can also point to gonorrhea, chlamydia, or in some cases bacterial vaginosis. Normal discharge ranges from clear to white and doesn’t have a strong odor, so a shift toward yellow or green, especially with a noticeable smell, is your body telling you something needs attention.
Trichomoniasis: The Most Likely Cause
Trichomoniasis, often called “trich,” is the most common non-viral sexually transmitted infection worldwide. It’s caused by a single-celled parasite that infects the vaginal lining, and the hallmark symptom is a thin or frothy discharge that ranges from clear to yellow or green with a foul, fishy smell. The CDC estimates millions of people in the United States are infected at any given time, yet most don’t know they have it because symptoms can be mild or absent entirely.
Beyond the discharge itself, trichomoniasis often causes burning, soreness, or itching around the genitals. You might feel discomfort when urinating or during sex, and some people notice pain in the lower abdomen. The infection shifts the vagina’s natural acidity significantly. A healthy vaginal pH sits between 4.0 and 4.5, but trichomoniasis can push it above 5.4 and sometimes as high as 6.5, which is one reason the discharge changes in color and smell.
Men can carry and transmit the parasite too, though their symptoms are often less obvious: irritation inside the penis, burning after urination or ejaculation, and occasionally a clear or pus-like discharge.
Other Infections That Cause Yellow-Green Discharge
Gonorrhea and chlamydia can both produce cloudy, yellow, or green discharge. These bacterial STIs sometimes occur alongside trichomoniasis, which complicates the picture. Trichomoniasis is strongly associated with the presence of other STIs, including gonorrhea, chlamydia, HPV, herpes, and HIV. Having one infection can make it easier to pick up another, so testing for multiple infections at once is standard practice.
Bacterial vaginosis (BV) is another possibility, though its discharge is more typically described as thin, gray-white to yellow, and uniform in texture rather than green or frothy. BV is caused by an imbalance in normal vaginal bacteria rather than a specific pathogen, and it also pushes vaginal pH above 4.5. The fishy odor can overlap with trichomoniasis, which is why a clinical test matters more than trying to self-diagnose based on appearance alone.
How It’s Diagnosed
A healthcare provider can usually identify the cause through a combination of a pelvic exam, a pH test, and a lab analysis of the discharge. For trichomoniasis, looking at a sample under a microscope is one of the most reliable methods. Nucleic acid testing (a type of swab test similar in concept to a COVID PCR) is also widely used because it’s highly accurate. Gonorrhea and chlamydia are typically tested from the same swab.
The color and smell of your discharge give useful clues, but they aren’t enough for a definitive diagnosis. Several infections overlap in how they look, so lab confirmation determines which treatment you actually need.
Treatment Is Straightforward
Trichomoniasis is curable with a short course of oral antibiotics. Women typically take a twice-daily antibiotic for seven days, while men often receive a single higher dose. The infection clears completely in most cases. If your discharge is caused by gonorrhea or chlamydia, those are also treated with antibiotics, though with different medications.
One critical detail: your sexual partner needs treatment at the same time, even if they have no symptoms. Trichomoniasis is notorious for bouncing back and forth between partners. If only one person is treated, reinfection is almost guaranteed. Avoid sexual contact until both of you have finished the full course and symptoms have resolved.
What Happens If You Ignore It
Untreated trichomoniasis isn’t just uncomfortable. It carries a high risk of developing pelvic inflammatory disease, a condition where infection spreads to the uterus and fallopian tubes and can cause chronic pain or fertility problems. In men, the parasite can lead to inflammation of the prostate or the tube behind the testicle, and in rare cases, infertility.
Perhaps the most serious consequence is that trichomoniasis increases the risk of acquiring and transmitting HIV. The infection causes microscopic inflammation in genital tissue, which creates easier entry points for other pathogens.
Yellow-Green Discharge During Pregnancy
If you’re pregnant and noticing yellow-green discharge, getting tested promptly is especially important. Trichomoniasis during pregnancy is linked to premature rupture of membranes, preterm delivery, and low birth weight. Research published in the Pakistan Journal of Medical Sciences found that pathological vaginal discharge during pregnancy was significantly associated with neonatal complications including respiratory distress, intensive care hospitalization, and early neonatal death. Treatment during pregnancy uses the same antibiotic and is considered safe.
Normal Discharge vs. Concerning Discharge
Vaginal discharge changes naturally throughout your menstrual cycle. Around ovulation it often becomes clear and stretchy, and at other times it may look white or slightly cloudy. None of that is cause for concern. The signs that something has shifted include a new or stronger odor (especially a fishy smell), a change to green, bright yellow, or gray, a frothy or lumpy texture, and any accompanying itching, burning, or pain. If your discharge has changed in two or more of these ways at once, an infection is the most likely explanation.