Yellowish green vaginal discharge typically signals an infection, most commonly a sexually transmitted infection like trichomoniasis, chlamydia, or gonorrhea. Normal discharge ranges from clear to white and doesn’t have a strong odor. When discharge shifts to yellow or green, it usually means your immune system is actively fighting something off, and the color itself comes from a biological process worth understanding.
Why Discharge Turns Green or Yellow
The color change happens because of your white blood cells. When your body detects an infection, it sends immune cells called neutrophils to the area. These cells contain an enzyme with a green pigment, similar to the pigment in blood but green instead of red. When large numbers of neutrophils concentrate in vaginal fluid, they tint the discharge yellow or green. The more intense the immune response, the greener the discharge tends to look.
This is the same reason pus looks yellowish green. It’s not the bacteria themselves causing the color. It’s your body’s defense response.
Trichomoniasis: The Most Common Cause
Trichomoniasis is the most common non-viral sexually transmitted infection worldwide, with an estimated 156 million new cases in 2020 alone. It’s caused by a parasite, not a bacterium or virus, and it produces one of the most recognizable patterns of abnormal discharge.
The classic signs include thin or frothy discharge that can be clear, white, yellow, or green, along with a distinctly foul smell. You may also notice itching, irritation, or discomfort during urination or sex. However, many people with trichomoniasis have no symptoms at all, which means the infection can go undetected for weeks or months.
Trichomoniasis is treated with a course of oral antibiotics, typically taken twice a day for seven days. Sexual partners need treatment at the same time to prevent reinfection.
Chlamydia and Gonorrhea
Both chlamydia and gonorrhea can produce yellow vaginal discharge or any discharge that looks different from your normal pattern. The American College of Obstetricians and Gynecologists lists yellow discharge as a key symptom of both infections. With gonorrhea, discharge may lean more toward a thicker, yellowish appearance. Chlamydia discharge is often lighter but still noticeably off from your baseline.
The tricky part is that both infections are frequently silent. Many women with chlamydia or gonorrhea have no obvious symptoms, or symptoms so mild they’re easy to dismiss. If you’re sexually active and noticing a change in your discharge color, testing for both infections is important even if you feel fine otherwise. Standard STI panels using a vaginal or urine swab can detect both.
Bacterial Vaginosis
Not every case of yellowish green discharge points to an STI. Bacterial vaginosis (BV) happens when the normal balance of bacteria in the vagina shifts, allowing certain species to overgrow. BV discharge is often grayish white, but it can take on a yellowish or greenish tint in some cases. The hallmark is a strong, fishy odor that tends to get worse after sex.
One way clinicians distinguish between causes is vaginal pH. A healthy vagina sits at a pH of around 4.5 or below. BV and trichomoniasis both push the pH higher, into the 5 to 6 range, while yeast infections keep the pH closer to normal. This is one reason a clinical exam is more reliable than guessing based on color alone.
What to Watch For Beyond Discharge
Discharge color and odor are important clues, but they’re rarely the full picture. Pay attention to whether you’re also experiencing lower abdominal pain, fever, pain during sex, burning with urination, or bleeding between periods. These symptoms together can indicate pelvic inflammatory disease (PID), which happens when an untreated infection like chlamydia or gonorrhea spreads from the vagina into the uterus or fallopian tubes.
PID doesn’t always announce itself dramatically. Some women have only mild discomfort and unusual discharge. But the longer it goes untreated, the higher the risk of lasting damage, including scarring that can affect fertility. Early treatment with antibiotics resolves most cases without complications.
Risks During Pregnancy
Yellowish green discharge during pregnancy deserves prompt attention because the infections behind it carry specific risks for both the pregnancy and the baby. Untreated chlamydia has been linked to preterm delivery, low birth weight, and eye or lung infections in newborns. Gonorrhea can be transmitted during delivery, potentially causing serious infections in the baby including bloodstream infections and blindness. Trichomoniasis during pregnancy increases the chance of delivering early or having a baby under 5.5 pounds.
All three infections are treatable during pregnancy with antibiotics that are safe for the developing baby. The key is catching them early, which is why prenatal care routinely includes STI screening.
Getting Tested
You can’t reliably diagnose the cause of yellowish green discharge at home. Color, consistency, and smell overlap enough between infections that even experienced clinicians rely on lab tests rather than visual assessment alone. The most accurate option is a nucleic acid amplification test, which detects genetic material from the specific organism causing the infection. These tests are highly sensitive and can be run from a vaginal swab or urine sample.
Older methods like examining a sample under a microscope are still used in some settings but miss a significant number of cases, particularly for trichomoniasis. If your initial test comes back negative but symptoms persist, ask about more sensitive testing options.
Most STI-related causes of abnormal discharge are straightforward to treat with a short course of antibiotics. Sexual partners typically need treatment as well, and you’ll want to avoid sex until both you and your partner have completed treatment to prevent passing the infection back and forth.