The most telling sign of bacterial vaginosis is a thin, grayish or white discharge with a fishy smell, especially after sex. Unlike a yeast infection, BV typically doesn’t cause intense itching or pain. About half of people with BV have no obvious symptoms at all, which makes it tricky to identify on your own.
What BV Discharge Looks and Smells Like
BV discharge has a distinct profile. It’s thin, almost milk-like in consistency, and coats the vaginal walls smoothly rather than clumping. The color ranges from off-white to gray to greenish. Volume tends to be heavier than normal.
The hallmark is a fishy odor that often gets stronger after unprotected sex. This happens because semen is alkaline, and it reacts with the bacteria causing the smell. You might also notice the odor during your period or after washing with soap. If your discharge is thick, white, and clumpy like cottage cheese, that points toward a yeast infection instead.
BV vs. Yeast Infection
These two get confused constantly because they both involve abnormal discharge, but they feel quite different. BV is driven by an overgrowth of certain bacteria, while yeast infections are caused by fungal overgrowth. Here’s how to tell them apart:
- Discharge texture: BV produces thin, watery discharge. Yeast infections produce thick, cottage cheese-like discharge.
- Smell: BV has a noticeable fishy odor. Yeast infections usually have little to no smell.
- Itching and pain: BV can cause mild irritation but typically doesn’t hurt. Yeast infections cause significant itching, burning, and sometimes pain during sex.
- Redness and swelling: BV rarely causes visible inflammation. Yeast infections often make the vulva red and swollen.
If you have both a strong odor and intense itching, it’s possible to have both infections at the same time, which is another reason testing matters more than guessing.
What Happens During a Doctor’s Visit
A doctor confirms BV by looking at a combination of signs, not just one. The standard approach checks for at least three of the following four things: thin, milky discharge that smoothly coats the vaginal walls; a vaginal pH above 4.5 (healthy vaginal pH sits below that); a fishy odor when a chemical solution is added to a sample of discharge; and the presence of “clue cells,” which are vaginal cells covered in bacteria, visible under a microscope.
The visit itself is straightforward. Your provider takes a swab of vaginal discharge during a pelvic exam. Results from the in-office tests come back within minutes. Some clinics send the swab to a lab for scoring under a microscope, where technicians grade the balance of healthy bacteria versus BV-associated bacteria on a 0 to 10 scale. A score of 0 to 3 means healthy, 4 to 6 is intermediate, and 7 to 10 confirms BV.
Can You Test at Home?
Over-the-counter vaginal pH test strips are available at most pharmacies. You insert a small strip, wait for it to change color, and compare it to a chart. A reading above 4.5 suggests something is off. The FDA notes that these strips show good agreement with a doctor’s pH reading.
The catch is that pH alone can’t diagnose BV. An elevated pH can also result from semen exposure, menstrual blood, soap residue, or other infections like trichomoniasis. And a normal pH doesn’t fully rule BV out either. These tests are best used as a first screening step. If your pH is elevated and you have the classic discharge and odor, BV is likely, but you still need a provider to confirm it and prescribe treatment.
What Causes the Bacterial Shift
Your vagina naturally contains a mix of bacteria, dominated by species that produce lactic acid and keep the environment slightly acidic. BV happens when that balance tips: the protective bacteria decline and other types multiply. This isn’t a sexually transmitted infection in the traditional sense, but sexual activity is one of the strongest triggers, particularly new or multiple partners. Douching, scented soaps and body washes near the vagina, and hormonal shifts can also disrupt the balance.
BV is extremely common and not a reflection of poor hygiene. In fact, over-cleaning is more likely to cause it than under-cleaning. The vagina is self-cleaning, and introducing products that alter its natural chemistry pushes things in the wrong direction.
Why It Keeps Coming Back
One of the most frustrating aspects of BV is recurrence. Many people find it returns within a few months of treatment. This happens because antibiotics kill the overgrown bacteria but don’t always restore the protective bacteria to their previous levels. The environment remains vulnerable to the same imbalance.
Recurrent BV sometimes requires a longer course of treatment or a maintenance regimen to keep the bacteria in check. If you’re dealing with repeat episodes, tracking your triggers (new products, timing in your cycle, sexual partners) can help identify patterns worth discussing with your provider.
Risks of Leaving BV Untreated
BV sometimes clears on its own, but leaving it untreated carries real risks. The bacterial imbalance makes you 3 to 4 times more susceptible to picking up chlamydia or gonorrhea if exposed, because the protective acidic environment is compromised. BV also increases the risk of pelvic inflammatory disease, a condition where infection spreads to the uterus and fallopian tubes. Subclinical PID, a low-grade version without obvious symptoms, is nearly three times more common in people with BV.
During pregnancy, untreated BV is linked to preterm birth and low birth weight. And PID itself can lead to chronic pelvic pain, ectopic pregnancy, and reduced fertility. Women with subclinical PID at the time of diagnosis have a 40% lower likelihood of becoming pregnant compared to those without it. These aren’t common outcomes, but they underscore why getting tested and treated matters, especially if you’re planning a pregnancy or notice recurring symptoms.