Bacterial vaginosis (BV) discharge is typically thin, grayish-white, and has a distinctive fishy smell. Unlike the thick, clumpy discharge of a yeast infection, BV discharge has a milklike consistency that smoothly coats the vaginal walls. It can also appear yellow-green in some cases. Understanding exactly what to look for helps you tell BV apart from other common vaginal infections.
Color, Texture, and Amount
BV discharge is most often described as gray or off-white, though it can lean yellow-green. The texture is thin and homogeneous, almost watery or slightly foamy. It coats the vaginal walls evenly rather than clumping or forming chunks. Some people notice it on underwear as a uniform wet spot rather than the patchy, cottage cheese-like residue typical of a yeast infection.
The amount varies. BV discharge can be profuse, meaning you may notice significantly more than your normal daily discharge. But it’s also possible to have BV with very little visible discharge, or even none at all. About half of people with BV don’t have noticeable symptoms.
The Fishy Odor
The smell is often the most recognizable sign. BV produces a fishy odor caused by certain chemicals released when anaerobic bacteria overgrow in the vagina. This odor tends to spike at specific times: after sex and during your period. Semen is alkaline, and menstrual blood raises vaginal pH as well. Both of these shifts make the smell more noticeable because the odor-causing compounds become more volatile in a less acidic environment.
If you’re noticing a fishy smell that gets stronger after unprotected sex, that pattern alone is a strong indicator of BV rather than another type of infection.
How BV Discharge Differs From Other Infections
Three common vaginal infections each produce distinctly different discharge, which makes visual comparison useful.
- BV: Thin, grayish or yellow-green, foamy or milky, fishy odor. Usually no itching or irritation.
- Yeast infection: Thick, white, odorless, often described as cottage cheese-like. Accompanied by itching, burning, and sometimes a white coating on the vaginal walls.
- Trichomoniasis: Frothy, yellow-green, foul-smelling (but not specifically fishy), and may contain small spots of blood. Often causes irritation and discomfort during urination.
The key distinction with BV is the combination of thinness and smell. Yeast infections are thick and don’t smell. Trichomoniasis can look somewhat similar to BV but is more likely to cause itching, burning, and visible irritation. BV itself rarely causes pain or significant itching.
What Happens During a Diagnosis
A healthcare provider can usually identify BV during a standard pelvic exam using a set of clinical markers. The CDC outlines four criteria, and meeting at least three confirms BV:
- Thin, homogeneous discharge with a milklike consistency coating the vaginal walls
- Vaginal pH above 4.5 (healthy vaginal pH typically sits at or below 4.5)
- Fishy odor detected during the exam
- Clue cells visible under a microscope
Clue cells are vaginal skin cells that have become so heavily coated with bacteria that their edges look ragged or “moth-eaten” under magnification. They’re a hallmark of BV and don’t appear with yeast infections or trichomoniasis. The pH test is simple: a small strip is touched to vaginal fluid. BV consistently raises pH above the normal acidic range.
When BV Has No Visible Symptoms
It’s worth knowing that BV doesn’t always announce itself with obvious discharge. Many people are diagnosed incidentally during a routine exam. If you have a mild case, the discharge may look close to your normal daily fluid, just slightly thinner or with a faint smell you only catch occasionally. The fishy odor after sex can sometimes be the only clue.
If your discharge has changed in color, consistency, or smell, comparing it against these descriptions can help you narrow down what’s going on. BV’s signature combination of thin gray discharge, a fishy smell that worsens after sex, and the absence of itching or pain is distinct enough to recognize, even before a lab confirms it.