Bacterial vaginosis (BV) produces a thin, milky discharge that smoothly coats the vaginal walls, often with a noticeable fishy smell. But more than half of all women with BV have no visible symptoms at all, which is part of what makes the condition tricky to identify on your own.
If you do have symptoms, here’s what to look for and how to tell BV apart from other common infections.
What BV Discharge Looks Like
The hallmark of BV is a thin, watery or milky discharge. It’s typically white or grayish-white, with a consistency the CDC describes as “homogeneous” and “milklike.” Unlike the chunky discharge you’d see with a yeast infection, BV discharge is smooth and even, almost like skim milk. It tends to coat the vaginal walls in a thin, uniform layer rather than clumping or collecting in thicker patches.
The amount of discharge varies. Some women notice a significant increase that shows on underwear, while others see only a slight change from their normal discharge. The color can range from off-white to a dull gray. It doesn’t usually look yellow or green. If your discharge is bubbly, frothy, or greenish-yellow, that pattern points more toward trichomoniasis, a sexually transmitted infection that requires different treatment.
The Fishy Smell
For many women, the smell is more noticeable than the look. BV produces a distinct fishy odor caused by volatile chemicals (specifically certain amines) released by the overgrown bacteria. This smell often becomes stronger after sex and during your period, because both semen and menstrual blood are more alkaline, which triggers the release of those odor-causing compounds.
The odor is one of the key ways doctors confirm BV in the exam room. A clinical test called the “whiff test” involves adding a drop of potassium hydroxide to a sample of discharge. If a fishy smell is released, it supports a BV diagnosis.
What BV Doesn’t Look Like
BV is surprisingly mild in its visible effects on the surrounding tissue. Unlike yeast infections or trichomoniasis, BV rarely causes redness, swelling, or irritation of the vulva. Your skin typically looks normal. Itching, if present at all, is mild. This is an important distinction because many people assume any vaginal infection will cause obvious irritation, and the absence of that irritation can make BV easy to dismiss or overlook.
Internally, the vaginal lining and cervix also look relatively normal during a BV infection. There are no characteristic sores, bumps, or red spots. Trichomoniasis, by contrast, can cause tiny red dots on the cervix known as a “strawberry cervix” pattern. BV simply doesn’t produce that kind of visible tissue change.
How BV Looks Different From a Yeast Infection
Since these two conditions are the most common causes of abnormal discharge, knowing the visual differences helps:
- Texture: BV discharge is thin, watery, and smooth. Yeast infection discharge is thick and clumpy, often described as looking like cottage cheese.
- Color: BV discharge is white to gray. Yeast infection discharge is usually white.
- Smell: BV has a fishy odor. Yeast infections typically have no strong smell.
- Irritation: BV causes little to no itching or redness. Yeast infections cause intense itching and often visible vulvar redness and swelling.
If you’re experiencing thick, clumpy discharge with significant itching but no fishy smell, a yeast infection is more likely. If you’re noticing thin, grayish discharge with a fishy odor but your skin looks and feels fine, that pattern fits BV.
When BV Has No Visible Signs at All
More than half of women who test positive for BV have no symptoms whatsoever. No unusual discharge, no odor, no discomfort. In these cases, the bacterial imbalance is only detectable through lab testing. This is why BV is sometimes discovered incidentally during a routine exam or a screening for something else entirely.
If you suspect BV but aren’t sure what you’re seeing, a healthcare provider can confirm the diagnosis using a few straightforward tests. They’ll check the discharge under a microscope for “clue cells,” which are normal vaginal wall cells that appear to have fuzzy, obscured borders because bacteria are clinging to their surface. They’ll also test the vaginal pH, which in BV rises above 4.5 (a healthy vaginal pH sits between 3.8 and 4.5). Meeting at least three of four clinical markers, including discharge appearance, clue cells, elevated pH, and a positive whiff test, confirms the diagnosis.
What the Discharge Pattern Means
BV isn’t caused by a single invading organism. It happens when the balance of bacteria naturally present in the vagina shifts, with a decline in protective bacteria and an overgrowth of other species. The thin, milky discharge is a byproduct of that bacterial overgrowth rather than a sign of tissue damage or inflammation, which is why the surrounding skin stays calm even when the discharge is noticeable.
This also explains why BV can come and go. Some women experience a single episode that resolves with treatment, while others deal with recurring episodes where the discharge and odor return periodically. The visual appearance stays consistent each time: thin, grayish-white, and smooth, without the redness or swelling that would signal a different type of infection.