The most common symptoms of bacterial vaginosis (BV) are a thin, grayish-white discharge and a noticeable “fishy” odor. But here’s the surprising part: the majority of people with BV have no symptoms at all. When symptoms do show up, they range from mild and barely noticeable to persistent and disruptive.
The Main Symptoms
BV produces a specific pattern of symptoms that tends to look and feel different from other vaginal infections. The hallmark signs include:
- Thin, watery discharge that may appear gray, white, or greenish
- A fishy odor that often becomes stronger after sex or during your period
- Vaginal itching, though usually mild
- Burning during urination
The discharge tends to be heavy in volume but thin in texture, almost like a coating rather than a thick fluid. Many people first notice BV not because of the discharge itself but because of the smell, which can be strong enough to detect through clothing.
Why It Smells That Way
The fishy odor isn’t random. It comes from specific chemical compounds, particularly trimethylamine and dimethylamine, that the overgrown bacteria produce in vaginal fluid. These are the same types of compounds responsible for the smell of rotting fish. When vaginal pH rises above 4.5 (a healthy vagina sits below that number), these compounds become more volatile, meaning they evaporate into the air more easily and the smell becomes stronger.
This is why the odor often intensifies after intercourse. Semen is alkaline, which temporarily raises vaginal pH and releases more of those odor-causing compounds. The same thing can happen during menstruation, since blood also shifts vaginal pH upward.
How BV Feels Different From a Yeast Infection
BV and yeast infections are the two most common vaginal infections, and people frequently confuse them. The differences are fairly reliable once you know what to look for.
BV discharge is thin and grayish with a strong fishy smell. Yeast infection discharge is thick, white, and clumpy, often described as looking like cottage cheese, and it typically has little to no odor. The sensation is different too. BV can cause mild irritation, but it rarely causes real pain. Yeast infections tend to bring intense itching and burning, particularly after intercourse. If the dominant symptom is smell, BV is more likely. If it’s itching and thick discharge, a yeast infection is more likely.
That said, it’s possible to have both at the same time, and some sexually transmitted infections produce overlapping symptoms. A clinical test is the only way to confirm which one you’re dealing with.
When There Are No Symptoms at All
In a nationally representative survey cited by the CDC, the majority of women with BV were asymptomatic. This means BV can be present and detectable on lab testing without producing any discharge, odor, or discomfort. Asymptomatic BV often goes undiagnosed because there’s no routine screening for it outside of pregnancy.
This matters because untreated BV, even without symptoms, can increase susceptibility to sexually transmitted infections and cause complications during pregnancy. If you’re pregnant and have BV, your baby is more likely to be born premature or at a low birth weight (under 5.5 pounds).
How BV Is Diagnosed
A healthcare provider can usually diagnose BV during a standard pelvic exam. They’ll look at the discharge, test vaginal pH (a reading above 4.5 suggests BV), and may examine a sample under a microscope. The odor test is straightforward: a small amount of potassium hydroxide is added to a discharge sample, and if it releases a fishy smell, that’s a strong indicator.
Home pH test strips are available over the counter and can give you a rough idea, but they can’t distinguish BV from other conditions that also raise vaginal pH, like trichomoniasis. A clinical visit gives you a definitive answer.
Symptoms Often Come Back
BV is treatable with antibiotics, typically taken orally or applied as a vaginal gel. Most people notice symptoms improving within a few days. The frustrating reality, though, is that recurrence is extremely common. Up to 66% of women experience BV again within a year of completing treatment, according to the American College of Obstetricians and Gynecologists.
Recurrent BV produces the same symptoms as the initial episode. If you’ve had BV before and recognize the smell or discharge returning, that pattern itself is useful information to share with your provider. ACOG now recommends that sexual partners be treated at the same time to help reduce recurrence, a shift from earlier guidelines that focused only on treating the person with symptoms.
Symptoms That Signal Something Else
BV does not cause fever, pelvic pain, or heavy bleeding. If you’re experiencing those alongside vaginal discharge, something else is going on, potentially a more serious infection like pelvic inflammatory disease. BV also doesn’t typically cause sores, blisters, or rashes. Discharge that’s bright yellow or green and frothy, rather than thin and grayish, points more toward trichomoniasis than BV. Any of these patterns warrants a different conversation with your provider than a straightforward BV diagnosis.