A fishy vaginal odor is almost always caused by bacterial vaginosis (BV), a common condition where the natural balance of bacteria in the vagina shifts. It is not a sexually transmitted infection, though sexual activity can trigger it. Getting rid of the smell typically requires antibiotics, but understanding what disrupts your vaginal environment can help prevent it from coming back.
Why the Smell Happens
A healthy vagina maintains a slightly acidic pH between 3.8 and 4.5, kept in check by beneficial bacteria that produce lactic acid. When that balance tips, a bacterium called Gardnerella and other anaerobic organisms multiply and produce compounds called amines. Those amines are what create the characteristic fishy smell.
The odor often becomes more noticeable after sex because semen is alkaline. When it comes into contact with these amine compounds, the smell intensifies. You might also notice it’s stronger around your period, since menstrual blood raises vaginal pH temporarily. A higher pH (less acidic) creates a friendlier environment for the bacteria that produce the odor.
Common Triggers to Avoid
Several everyday habits can push vaginal pH out of its healthy range and set the stage for BV:
- Douching and feminine hygiene products. Women who use douches, scented washes, or vaginal deodorants are more likely to develop BV, yeast infections, and urinary tract infections. The vagina is self-cleaning. Warm water on the external vulva is all you need.
- Scented soaps and body washes. Even mild-looking products with fragrance can alter pH when they come into contact with vaginal tissue.
- New or multiple sexual partners. Sexual activity introduces new bacteria. This doesn’t make BV an STI, but it is a well-established trigger.
- Tight, non-breathable clothing. Synthetic underwear and tight pants trap moisture, creating conditions where harmful bacteria thrive more easily.
Switching to unscented soap, wearing cotton underwear, and stopping any internal cleaning products can sometimes resolve a mild odor on their own within a few days. If the smell persists or comes with discharge, that usually signals an active infection that needs treatment.
What BV Discharge Looks Like
BV typically produces a thin, grayish-white discharge with a noticeable fishy smell. This is different from a yeast infection, which causes thick, white, cottage cheese-like discharge that itches but rarely smells. It also differs from trichomoniasis, a sexually transmitted parasite that causes yellow-green or gray discharge with odor, often accompanied by irritation, burning during urination, and redness.
If your discharge is gray or white and the primary complaint is the smell rather than itching or pain, BV is the most likely cause. But because these conditions can overlap or mimic each other, a provider can confirm the diagnosis with a simple swab test.
How BV Is Treated
BV requires antibiotics. Over-the-counter products marketed for vaginal odor do not treat the underlying bacterial imbalance. The CDC recommends three first-line options: oral antibiotics taken twice daily for seven days, an antibiotic gel applied internally once daily for five days, or an antibiotic cream applied internally at bedtime for seven days. Your provider will help you choose based on your preferences and any history of side effects.
Most people notice the odor fading within a couple of days of starting treatment, and the full course clears the infection. Alcohol should be avoided during oral antibiotic treatment and for 24 hours afterward, as the combination can cause nausea and vomiting.
Why It Keeps Coming Back
Recurrence is the most frustrating part of dealing with BV. Within 6 to 12 months of finishing antibiotics, 50 to 80 percent of women experience the odor and discharge again. This high recurrence rate is one of the biggest challenges in treating the condition, and researchers still don’t fully understand why some women’s vaginal bacteria repeatedly fall out of balance.
A few strategies can reduce your risk of recurrence. Avoiding douching is the single most impactful change. Using condoms helps by preventing semen from raising vaginal pH after sex. Some providers recommend boric acid vaginal suppositories as a maintenance option after antibiotic treatment. Boric acid works by helping restore the acidic environment that keeps harmful bacteria in check. It’s available over the counter, but it should only be used vaginally (never orally, as it’s toxic if swallowed) and is best started under a provider’s guidance, especially if you’re using it to manage repeat infections.
Probiotics marketed for vaginal health are widely sold, but the evidence supporting them for BV prevention remains inconsistent. They won’t hurt, but they shouldn’t be relied on as a sole strategy if you’re dealing with frequent recurrences.
What You Can Do Right Now
If the fishy smell just started and is mild, try eliminating potential triggers first: stop using any scented products near your vulva, switch to cotton underwear, and give your body a few days. If the odor persists beyond a week, is accompanied by discharge, or gets worse after sex, schedule a visit with your provider. The appointment is quick, a swab takes seconds, and treatment works fast once started.
For women dealing with their third or fourth round of BV in a year, it’s worth having a direct conversation with your provider about a longer-term prevention plan. This might include extended antibiotic courses, boric acid suppositories, or identifying specific personal triggers that keep restarting the cycle.