The fishy smell associated with bacterial vaginosis (BV) comes from specific chemicals produced by an overgrowth of anaerobic bacteria in the vagina. The only reliable way to make it go away is to treat the underlying bacterial imbalance, either with prescription antibiotics or by restoring the vagina’s naturally acidic environment. Masking the odor with sprays or washes won’t work and can actually make things worse.
What Causes the Smell
A healthy vagina is dominated by lactobacilli, bacteria that produce lactic acid and keep the pH between 2.8 and 4.2. When BV develops, those protective bacteria get crowded out by anaerobic species that thrive in less acidic conditions. The vaginal pH rises above 4.5, and the new bacteria produce compounds called biogenic amines, specifically putrescine, cadaverine, and trimethylamine. These are the direct source of the characteristic fishy odor.
The smell often becomes more noticeable after sex. Semen is alkaline, and when it mixes with the vaginal environment, it raises the pH further, which causes those amine compounds to volatilize more easily. This is why some people first notice the odor during or after intercourse, even if the infection has been present for a while.
Prescription Treatment Is the Fastest Fix
Antibiotics are the standard first-line treatment. The CDC recommends either an oral antibiotic taken twice daily for seven days or a vaginal gel or cream applied for five to seven days. Most people notice the odor fading within the first few days of treatment, though finishing the full course matters for preventing a quick return.
These treatments work by directly killing the overgrown anaerobic bacteria, which stops the production of odor-causing amines. Once the bacterial population shifts back and lactobacilli can recolonize, your vaginal pH drops and the environment becomes self-regulating again.
Over-the-Counter Options
If you’re looking for something you can try before or alongside a prescription, two categories have some clinical support.
Lactic acid vaginal gels work by lowering vaginal pH directly, mimicking what lactobacilli do naturally. In a head-to-head pilot study comparing lactic acid gel to oral antibiotics, the gel had lower clinical cure rates in the short term but performed equally well for subjective symptom relief and BV recurrence prevention over six months. It’s not a replacement for antibiotics in a clear-cut BV case, but it may help with mild symptoms or as a maintenance strategy.
Boric acid suppositories (600 mg) are sometimes used for resistant or recurrent BV. A systematic review found that side effects occurred in about 7.3% of users and were typically mild and temporary. For recurrent BV, some clinicians suggest using them two to three times per week as maintenance. Boric acid is not safe to take orally and should never be used during pregnancy.
Probiotics After Antibiotics
Taking a Lactobacillus-based probiotic after antibiotic treatment can help prevent the odor from coming back. A phase 2b clinical trial tested a vaginal probiotic containing Lactobacillus crispatus, applied over 11 weeks following antibiotic treatment. The result was a 34% reduction in BV recurrence at 12 weeks compared to placebo. By 24 weeks, there was still a 27% reduction.
There’s an important caveat: the probiotic only worked in women whose initial antibiotic treatment fully cleared the BV. If the antibiotics didn’t wipe out the overgrown bacteria first, adding lactobacilli on top didn’t help. The takeaway is that probiotics are a follow-up strategy, not a standalone treatment. Clearing the infection first gives the beneficial bacteria room to establish themselves. About 79% of women in the trial successfully colonized with the probiotic strain when given after effective antibiotics.
Habits That Make BV Worse
Several common hygiene practices directly disrupt the vaginal microbiome and can either trigger BV or make an existing case harder to resolve.
Douching is the most well-studied offender. A longitudinal study of over 3,600 women found that regular douching increased the risk of BV by 21%. Research in Kenyan women showed that vaginal washing with water alone, or water and soap, reduced the likelihood of having protective lactobacilli by 40%. Even more concerning, increased washing frequency was linked to a greater loss of the hydrogen peroxide-producing lactobacilli that are most effective at keeping harmful bacteria in check.
Feminine hygiene products are similarly problematic. One study found that women using any feminine hygiene product had three times the odds of reporting BV, UTIs, or STIs. Feminine washes and gels specifically were associated with 3.5 times the odds of BV. Lab research has shown that certain vaginal moisturizers completely killed lactobacilli within 24 hours of exposure. These products are marketed as though the vagina needs help staying clean, but they actively undermine its self-cleaning system.
Habits That Help
The vagina maintains itself when you don’t interfere with its pH. Practical steps that support this process include washing the external vulva only (with plain water or a mild, unscented soap), wearing cotton underwear or breathable fabrics, and changing out of wet swimwear or sweaty workout clothes promptly. None of these will cure an active infection, but they reduce the odds of recurrence.
Avoiding scented products in the genital area, including scented pads, tampons, and laundry detergent for underwear, removes another source of chemical disruption. If you use condoms, they can help by preventing alkaline semen from repeatedly raising your vaginal pH.
When the Smell Keeps Coming Back
BV recurrence is frustratingly common. For people who experience multiple episodes, suppressive therapy with a vaginal antibiotic gel used twice weekly for three months or longer has been shown to reduce recurrences. The downside: the benefit tends to disappear once suppressive therapy stops.
Recurrent BV is also worth a closer look to rule out other causes of vaginal odor. Trichomoniasis, a sexually transmitted parasitic infection, can produce a similar smell alongside greenish or frothy discharge. A yeast infection, by contrast, typically causes thick white discharge with itching but minimal odor. If the smell persists despite treatment, lab testing can distinguish between these conditions and ensure you’re treating the right thing.
Combining antibiotic treatment with a probiotic follow-up and eliminating the hygiene habits that suppress lactobacilli gives you the best shot at long-term resolution. The odor is a symptom of a bacterial imbalance, not a hygiene failure, and treating it means restoring the environment rather than covering it up.