Bacterial vaginosis (BV) typically produces a thin, grayish-white discharge. It often looks milky or watery rather than thick, and it tends to coat the vaginal walls evenly. The color can range from off-white to a noticeable gray, and it’s usually accompanied by a fishy smell that becomes stronger after sex or during a period.
What BV Discharge Looks Like
The hallmark of BV discharge is its consistency as much as its color. It’s thin and homogeneous, almost like skim milk, rather than clumpy or chunky. The grayish-white color distinguishes it from normal discharge, which is usually clear to slightly white and changes in thickness throughout your menstrual cycle. BV discharge also tends to be heavier in volume than what you’re used to.
The fishy odor is the other major giveaway. Normal discharge has a mild scent or none at all. BV discharge has a distinct smell that many people notice most after intercourse or when washing. If you’re seeing thin, grayish discharge with an unusual odor, those two signs together strongly point toward BV.
BV Discharge vs. Yeast Infection Discharge
These two conditions are easy to confuse, but their discharge looks quite different. A yeast infection produces thick, white, cottage cheese-like clumps. BV produces thin, grayish, watery discharge. The texture difference is the fastest way to tell them apart at home.
The symptoms surrounding the discharge also differ. Yeast infections cause significant itching and burning, especially during sex. BV can cause mild irritation, but pain and intense itching are not typical. Yeast infections rarely produce a strong odor, while BV almost always does. Getting the distinction right matters because they require completely different treatments: antibiotics for BV, antifungals for yeast.
What Causes the Change in Discharge
A healthy vagina is dominated by beneficial bacteria that produce lactic acid and other antimicrobial compounds. These keep the vaginal environment acidic (below a pH of 4.5) and hold harmful bacteria in check. When those protective bacteria decline, opportunistic species multiply rapidly, increasing in concentration by 100 to 1,000 times their normal levels. That bacterial shift is what changes the color, consistency, and smell of your discharge.
The overgrowth raises vaginal pH above 4.5, creating a less acidic environment where more problematic bacteria thrive. The fishy odor comes from compounds these bacteria release, which become more volatile in alkaline conditions. This is why the smell often intensifies after sex, since semen is naturally alkaline.
How BV Is Diagnosed
A clinician can often diagnose BV during a standard exam. The clinical criteria require at least three of four signs: the characteristic thin, milky discharge; a vaginal pH above 4.5; a fishy odor; and the presence of “clue cells” (vaginal cells coated with bacteria) visible under a microscope. In many cases, the appearance of the discharge and the smell are enough to prompt testing, and results come back quickly.
BV is not a sexually transmitted infection, though sexual activity can increase your risk. It’s the most common vaginal condition in women of reproductive age, and many people who have it experience no symptoms at all. If you do notice grayish discharge with a fishy smell, getting tested is straightforward and typically involves a simple swab.
Treatment and Recurrence
BV is treated with antibiotics, either taken orally or applied as a vaginal gel or cream. Most courses last five to seven days, and symptoms usually start improving within a few days of starting treatment. The infection itself clears in the majority of cases with a single course.
The bigger challenge is recurrence. Between 50% and 80% of women experience BV again within a year of completing antibiotics. The bacterial balance can be disrupted again by the same factors that caused the initial episode, including douching, new sexual partners, or shifts in the vaginal microbiome that researchers still don’t fully understand. If you find yourself dealing with repeated episodes, your provider may suggest a longer or different treatment approach.
Why BV Matters During Pregnancy
BV carries specific risks for pregnant women. In one study, the preterm birth rate before 34 weeks was nearly four times higher in women with BV compared to those without (22.7% vs. 6.2%). Babies born to mothers with BV had significantly lower birth weights, averaging 2,450 grams compared to 2,950 grams. Rates of neonatal intensive care admission were also more than double in the BV group.
These risks make it worth paying attention to discharge changes during pregnancy. Grayish, thin, fishy-smelling discharge at any point during pregnancy warrants a conversation with your provider, since early treatment can reduce the chance of complications.