Bacterial vaginosis

Bacterial vaginosis is the most common vaginal condition in people of reproductive age, affecting roughly a third at any given time. Despite that, most people have never heard of it until they have it, and many are told they have a "yeast infection" first.

What BV actually is

BV is not an infection in the way most people picture one. Nothing arrives from outside. What happens is a shift in the balance of bacteria already present.

A healthy vagina is dominated by Lactobacillus species producing lactic acid, keeping pH between roughly 3.8 and 4.5. In BV, lactobacilli decline and anaerobic organisms increase substantially: Gardnerella vaginalis, Prevotella, Atopobium vaginae, Mobiluncus and others. Overall bacterial numbers rise, diversity rises, and acidity falls.

Those anaerobes produce volatile amines, which is where the characteristic odor comes from. See what a healthy vaginal microbiome looks like for the underlying ecology.

Signs

• Thin, watery discharge, gray or off-white, often more than usual.
• A fishy odor, characteristically stronger after sex or during your period, because semen and blood are alkaline and release the amines.
• Mild or no itching. Prominent itching points more toward yeast.
• Sometimes burning when urinating, or discomfort during sex.

What increases the risk

• Douching. One of the strongest modifiable risk factors: it flushes out lactobacilli directly.
• A new or multiple sexual partners. Sexual activity is clearly associated with BV, though the relationship is not a simple transmission model.
• Sex between women. Concordance rates between female partners are high.
• Not using condoms. Semen is alkaline and repeated exposure raises pH.
• Smoking. Consistently associated with increased risk.
• Antibiotics taken for anything, which deplete lactobacilli along with the target.
• Intrauterine devices, in some studies.

Is BV a sexually transmitted infection?

Not classified as one, though the picture is more complicated than "no". BV is strongly associated with sexual activity, is rare in people who have never had sex, and recent research suggests male partners can carry the associated bacteria and contribute to recurrence. Some guidelines have begun to consider partner treatment in recurrent cases. It is best understood as sexually associated rather than sexually transmitted. More in why BV keeps coming back.

Why it is worth treating

BV is uncomfortable, but the reason clinicians take it seriously is what it is associated with:

• Increased susceptibility to STIs, including HIV, gonorrhea, chlamydia and herpes; the acidic barrier is part of your defense.
• Pelvic inflammatory disease, particularly after gynecological procedures.
• In pregnancy, association with preterm birth and low birth weight. Any BV symptoms during pregnancy should be assessed promptly.
• Post-surgical infection risk after hysterectomy or termination.

How it is diagnosed

Clinicians typically use Amsel criteria, requiring three of four: thin homogeneous discharge; vaginal pH above 4.5; a positive whiff test (fishy odor when potassium hydroxide is added); and clue cells on microscopy. Nugent scoring on a Gram-stained slide is the research standard. Molecular tests are increasingly available.

No at-home product, ours included, replicates this. pH is a genuinely useful component, which is why at-home pH testing exists, but pH alone is raised by menstruation, semen, douching and menopause too. See vaginal pH.

Treatment

BV is treated with antibiotics, usually:

• Metronidazole, oral for seven days or as a vaginal gel.
• Clindamycin, vaginal cream or oral.
• Tinidazole or secnidazole as alternatives.

Complete the full course even once symptoms settle. Note that clindamycin cream is oil-based and can weaken latex condoms and diaphragms.

Reducing the chance of recurrence

Recurrence is common (over half within a year) and gets its own detailed article. In brief, the evidence supports: stop douching entirely; use condoms consistently; stop smoking; avoid scented internal products; and speak to a clinician about suppressive regimens if you have repeated episodes.

Probiotics are frequently recommended online. The evidence is mixed and strain-specific, and most commercial products have not been tested for this purpose. Discuss it with a clinician rather than assuming.

When to see a doctor

See a clinician for a first episode, symptoms that persist after treatment, recurrence within a few months, symptoms during pregnancy, or any fever, pelvic pain or unusual bleeding. How to make that appointment count.