The fishy smell from bacterial vaginosis comes from specific chemicals produced by an overgrowth of harmful bacteria, and the only reliable way to eliminate it is to treat the underlying infection. Antibiotics clear most cases within a week, but the smell often returns because BV has a recurrence rate of 50 to 80 percent within a year of treatment. Getting rid of the odor for good means treating the infection and then taking steps to keep your vaginal microbiome balanced long-term.
What Actually Causes the Smell
The odor isn’t caused by poor hygiene. It’s the byproduct of a chemical chain reaction happening inside your vagina. When BV takes hold, protective lactobacilli bacteria get crowded out by a mix of other organisms that work together to produce foul-smelling compounds. A bacterium called Dialister micraerophilus produces putrescine and cadaverine, two aptly named chemicals responsible for the rotting-fish smell. It can’t do this alone, though. It relies on another organism, Fannyhessea vaginae, to break down the amino acid arginine into a precursor compound that Dialister then converts into those odor molecules. A separate group of bacteria produces trimethylamine, the same chemical responsible for the smell of spoiled seafood, primarily by breaking down a compound called betaine.
All of this happens because vaginal pH has risen above its normal range. A healthy vagina sits below 4.5 on the pH scale, kept acidic by lactic acid that lactobacilli produce. When that acid barrier drops, odor-causing bacteria thrive. The smell tends to be strongest after sex and during your period because semen and blood are both alkaline, temporarily raising pH even further and releasing more of those volatile amines.
Antibiotic Treatment Is the First Step
Prescription antibiotics are the most effective way to stop the odor at its source. Your provider will typically prescribe either an oral antibiotic or a vaginal gel or cream, both taken for about seven days. Most people notice the smell fading within two to three days of starting treatment, and it’s usually gone by the time you finish the course.
The challenge is keeping it gone. Between 50 and 80 percent of women experience a recurrence within 6 to 12 months of finishing antibiotics. For people dealing with multiple recurrences, the CDC notes that a longer protocol may help: a week of oral antibiotics, followed by vaginal boric acid suppositories (600 mg daily) for 21 days, then a suppressive vaginal gel used twice weekly for four to six months. This stepwise approach addresses the immediate infection and then works to prevent the bacterial overgrowth from re-establishing itself.
Why the Smell Keeps Coming Back
Antibiotics kill the overgrown bacteria, but they don’t automatically restore a healthy population of lactobacilli. Think of it like clearing weeds from a garden without replanting anything. The conditions that allowed BV to develop in the first place, whether that’s pH disruption, sexual transmission of bacteria, or a weakened microbial community, often remain after treatment ends.
There’s also growing evidence that BV-associated bacteria can be shared between sexual partners. The bacteria live in the penile microbiome and can be reintroduced during unprotected sex, effectively reseeding the infection. Using condoms consistently after treatment may reduce recurrence risk, though research on treating male partners directly is still limited.
Habits That Make BV Worse
Douching is one of the strongest risk factors. Women who douche weekly are five times more likely to develop BV than women who don’t, according to the Office on Women’s Health. Douching strips away protective bacteria and disrupts vaginal acidity, creating exactly the conditions odor-causing organisms need. It also only masks the smell temporarily while making the underlying problem worse.
Scented tampons, pads, vaginal sprays, and perfumed soaps carry similar risks. They introduce chemicals that can irritate vaginal tissue and shift the microbial balance. The vagina is self-cleaning. Warm water on the external vulva is all you need. Internal washing of any kind, with any product, works against you.
Diet and Your Vaginal Microbiome
What you eat appears to influence which bacteria dominate your vaginal ecosystem. A 2025 study published in Frontiers in Cellular and Infection Microbiology found that higher intake of red and processed meat was associated with a vaginal microbiome profile dominated by BV-causing bacteria rather than protective lactobacilli. Alcohol consumption was also significantly linked to higher levels of Gardnerella, one of the key organisms involved in BV.
On the protective side, diets higher in fiber, total carbohydrates, and vegetable proteins correlated with lower Gardnerella levels. Previous research has also linked higher intake of folate, vitamin A, and calcium with reduced BV risk. Interestingly, the relationship between sugar and vaginal health is nuanced. Total carbohydrates appeared protective, but simple sugars like glucose and fructose were positively correlated with some BV-associated bacteria, including Dialister, the very organism that produces putrescine.
None of this means diet alone can cure BV. But if you’re dealing with recurrent infections, shifting toward more plant-based proteins, fiber-rich foods, and fewer processed meats while cutting back on alcohol may help create an environment where protective bacteria can hold their ground.
Probiotics for Restoring Healthy Bacteria
Oral probiotics containing specific strains of lactobacilli show promise for tipping the vaginal microbiome back toward a healthier state. In a randomized, placebo-controlled trial, women who took capsules containing Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 daily for 14 days saw a statistically significant improvement in their vaginal flora compared to women taking a placebo. The improvement was measured using the Nugent score, a standard lab assessment of vaginal bacterial balance, with the probiotic group shifting three points toward healthier flora while the placebo group showed no change.
These aren’t the same lactobacilli found in regular yogurt. If you’re going to try probiotics, look for products that specifically contain the GR-1 and RC-14 strains, as these are the most studied for vaginal health. Probiotics work best as a complement to antibiotic treatment, not a replacement for it. They may help your body recolonize with the right bacteria after antibiotics have done the initial clearing.
What Won’t Fix the Smell
Perfumed products, douches, and deodorant sprays will temporarily cover the odor while actively making the infection worse. Apple cider vinegar rinses, tea tree oil, and garlic, commonly recommended online, lack strong clinical evidence for treating BV and carry the risk of irritating delicate vaginal tissue or further disrupting your microbiome.
If you’ve had a fishy odor lasting more than a few days, especially with thin grayish-white discharge, it’s worth getting tested. A healthcare provider can confirm BV quickly, often in a single visit, using a pH test and microscopic examination of vaginal discharge. A vaginal pH above 4.5 is found in 80 to 90 percent of BV cases, and the diagnosis is straightforward. The sooner you start targeted treatment, the sooner the smell resolves, and the better your chances of preventing a cycle of recurrence.