The most recognizable symptom of bacterial vaginosis (BV) is a thin, off-white, gray, or greenish vaginal discharge with a fishy smell. But here’s the surprising part: in a nationally representative survey cited by the CDC, the majority of women with BV had no symptoms at all. That means BV can be present and causing changes in your body without you ever noticing something is off.
What BV Discharge Looks and Smells Like
BV discharge is distinct from what you’d see with other vaginal infections. It tends to be thin and watery or slightly foamy, with a grayish or greenish tint. The amount is often noticeably more than your normal discharge. The hallmark, though, is the smell: a fishy odor that can range from faint to strong and typically becomes more noticeable after sex.
That odor has a specific biological explanation. When the normal balance of vaginal bacteria shifts, certain species (particularly Prevotella and Dialister) begin producing chemical compounds called amines, including putrescine and cadaverine. These are the same compounds responsible for the smell of decaying organic matter. Interestingly, Gardnerella vaginalis, the bacterium most commonly associated with BV, doesn’t produce these amines on its own. Instead, it releases amino acids and other metabolites that feed the amine-producing bacteria. It’s a cooperative process between multiple bacterial species, which is part of why BV can be stubborn to treat.
Semen is alkaline, which is why the smell often intensifies after unprotected sex. The higher pH releases more of those amine compounds into the air, making what might have been a subtle odor suddenly very noticeable.
Other Physical Symptoms
Beyond discharge and odor, BV can cause mild itching or irritation around the vulva and vaginal opening. Some people experience a burning sensation during urination. These symptoms are generally less intense than what you’d feel with a yeast infection, and many people with BV don’t experience them at all. Pain during sex is possible but not the norm.
BV rarely causes redness, significant swelling, or the kind of intense itching that keeps you up at night. If those symptoms are prominent, a different infection may be involved.
How BV Symptoms Differ 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.
- Discharge texture: BV discharge is thin, watery, or foamy. Yeast infection discharge is thick, white, and often compared to cottage cheese.
- Odor: BV produces a fishy smell. Yeast infections typically have no odor or a faintly bread-like smell.
- Itching: Intense vulvar itching is the defining feature of a yeast infection. BV may cause mild itching, but it’s not usually the main complaint.
- Color: BV discharge is grayish, greenish, or off-white. Yeast discharge is white.
Getting the distinction right matters because the treatments are completely different. Using an over-the-counter yeast treatment when you actually have BV won’t help and can delay proper care.
When BV Has No Symptoms at All
A large portion of BV cases are completely silent. You feel fine, your discharge seems normal, and you have no odor. The infection only shows up when a healthcare provider happens to test for it during a routine exam or while investigating something else, like an abnormal Pap result or a positive STI screen.
This matters because even without symptoms, BV changes the vaginal environment in ways that affect your health. Your vaginal pH rises above 4.5 (normal is below that), and the protective bacteria that produce hydrogen peroxide decline. That shift creates a more hospitable environment for sexually transmitted infections. Research has linked BV to increased susceptibility to HIV, gonorrhea, chlamydia, trichomoniasis, herpes, and HPV. One longitudinal study found that women with BV were 1.6 times more likely to acquire gonorrhea or chlamydia compared to women without it.
BV Symptoms During Pregnancy
BV during pregnancy carries the same symptoms as at any other time, so it can easily go unnoticed. The stakes, however, are higher. Pregnant people with BV face an increased risk of preterm birth and delivering a baby at low birth weight, defined as under 5.5 pounds. The CDC identifies premature delivery as one of the serious health risks of untreated BV during pregnancy.
Because BV is so often asymptomatic, some providers test for it during early prenatal visits, particularly for people with a history of preterm birth. If you’re pregnant and notice any change in your discharge, even a subtle one, it’s worth bringing up at your next appointment. Treatment during pregnancy is both safe and considered important.
How BV Is Confirmed
You can’t reliably diagnose BV on your own. The symptoms overlap too much with other conditions, and the most common symptom is having no symptoms at all. A healthcare provider will typically take a sample of vaginal discharge and evaluate it in one of two ways.
The simpler method checks a few clinical markers: the appearance and consistency of the discharge, the vaginal pH (above 4.5 suggests BV), whether a fishy odor is released when a chemical solution is added to the sample, and what the cells look like under a microscope. The presence of “clue cells,” which are vaginal cells coated in a film of bacteria, is one of the most reliable indicators.
A more precise laboratory method scores the bacterial population on a scale of 0 to 10. A score of 0 to 3 indicates normal flora, 4 to 6 is intermediate, and 7 to 10 confirms BV. This scoring system gives a clearer picture of how far the bacterial balance has shifted, which can be useful for borderline cases.
At-home vaginal pH test strips are available and can tell you if your pH is elevated, but a high pH alone doesn’t confirm BV. Trichomoniasis and other conditions also raise vaginal pH. The test is a reasonable first step if you’re unsure whether your symptoms warrant a visit, but it can’t replace a proper evaluation.