A fishy vaginal odor is almost always caused by an overgrowth of certain bacteria in the vagina, a condition called bacterial vaginosis (BV). It’s the most common vaginal infection in women of reproductive age, and it’s not a sign of poor hygiene. The smell comes from specific chemicals that these bacteria produce, and while some habits can help prevent it, getting rid of an established fishy odor usually requires treatment.
Why the Smell Happens
A healthy vagina maintains an acidic environment, with a pH between 4.0 and 4.5. Beneficial bacteria called lactobacilli keep the pH low and crowd out harmful organisms. When that balance shifts and other bacteria take over, the vagina’s pH rises above 4.5, creating conditions where odor-producing microbes thrive.
These bacteria break down amino acids and release compounds called biogenic amines, including putrescine, cadaverine, and trimethylamine. Those names hint at the problem: they’re the same chemicals responsible for the smell of rotting fish. The bacteria pump these compounds out of their cells in large quantities, which is why the odor can be strong and persistent. It often becomes more noticeable after sex or during your period, because semen and menstrual blood are both alkaline and temporarily raise vaginal pH even further.
BV Isn’t the Only Possible Cause
Trichomoniasis, a sexually transmitted infection caused by a parasite, can also produce a fishy smell. The discharge tends to look different: greenish-yellow and sometimes frothy, compared to BV’s thin, grayish-white discharge. Trichomoniasis also typically causes itching, burning, and genital redness, while BV is often painless aside from the odor. With trichomoniasis, vaginal pH is usually above 5.4, even higher than what’s seen with BV.
A forgotten tampon or other retained object can also cause a strong fishy odor. This is less common but worth considering if the smell appeared suddenly and is unusually intense. Removing the object resolves it quickly, though you may need a healthcare provider’s help.
What Actually Gets Rid of It
If the odor is mild, recent, and your only symptom, a few days of the hygiene adjustments below may be enough to let your vaginal flora rebalance on its own. But a persistent fishy smell that lasts more than a week, or one accompanied by unusual discharge, typically means BV has set in and needs medical treatment.
A healthcare provider can diagnose BV quickly using a combination of clinical signs: thin grayish discharge, a pH above 4.5, a positive “whiff test” (where the fishy smell intensifies when a solution is applied to a sample), and the presence of clue cells under a microscope. Meeting three of those four criteria confirms the diagnosis.
The standard treatment is a course of antibiotics, either taken orally or applied as a vaginal gel or cream. Most people notice the smell fading within a few days of starting treatment, with full resolution by the end of the course. The frustrating part is recurrence: BV comes back in roughly half of treated women within 12 months, which is why prevention habits matter so much.
Boric Acid for Recurrent Odor
For women who keep getting BV after antibiotics, boric acid vaginal suppositories are an option that many clinicians now recommend. A common approach is to complete a round of antibiotics first, then use 600 mg boric acid suppositories daily for up to 21 days, followed by a maintenance regimen of two to three times per week. In clinical surveys, about 77% of women using boric acid regimens reported satisfaction with the results. Notably, those who skipped the initial antibiotic treatment and used boric acid alone were less likely to be satisfied, suggesting the combination works better than boric acid on its own.
Boric acid suppositories are inserted vaginally only. They should never be taken by mouth. They’re available over the counter at most pharmacies.
Probiotics and Restoring Healthy Bacteria
Because BV is fundamentally a problem of lost lactobacilli, there’s growing interest in using probiotics to rebuild the vaginal microbiome. A randomized, placebo-controlled trial tested capsules containing specific strains of Lactobacillus crispatus in women with BV. Both oral and vaginal probiotic capsules reduced symptoms over three months, with measurable improvements in odor, discharge, and itching. Women who used the vaginal capsules showed increased lactobacilli counts and decreased levels of BV-associated bacteria.
Not all probiotic supplements are equally useful here. Look for products that specifically contain Lactobacillus crispatus or Lactobacillus rhamnosus, which are the strains with the most evidence for vaginal health. General gut-health probiotics won’t necessarily colonize the vagina.
Daily Habits That Prevent the Smell
The single most important thing you can avoid is douching. Douching kills the protective lactobacilli that keep harmful bacteria in check. In one study, 41% of women who douched had bacterial vaginosis. The products used in douching often contain antimicrobial agents that are directly toxic to lactobacilli, creating exactly the conditions that cause fishy odor. Your vagina is self-cleaning. Douching to fix the smell will almost certainly make it worse.
Beyond that, a few straightforward habits help maintain the acidic, lactobacillus-friendly environment your vagina needs:
- Wash externally only. Use mild, unscented soap and warm water on your vulva (the outer area). Nothing needs to go inside the vaginal canal.
- Wear breathable fabrics. Cotton underwear allows airflow and reduces the warm, moist conditions that encourage bacterial overgrowth. Avoid thongs and tight-fitting synthetic fabrics when possible.
- Change out of sweaty clothes promptly. Sitting in damp workout clothes or a wet swimsuit for hours gives opportunistic bacteria an advantage.
- Skip scented products. Scented pads, sprays, wipes, and bubble baths can irritate vulvar tissue and disrupt pH.
When the Odor Signals Something More
A fishy smell on its own is uncomfortable but not dangerous. However, untreated BV can increase susceptibility to sexually transmitted infections and, during pregnancy, raises the risk of preterm delivery. If the odor comes with itching, burning during urination, or greenish discharge, trichomoniasis or another infection may be involved, and that requires a different treatment than BV. A simple office visit with a swab test is usually all it takes to sort out which infection you’re dealing with and get the right prescription.