BV or thrush? How to tell the difference

Medically reviewed by Muhammad A Jalil, Superintendent Pharmacist (GPhC Reg No: 2236161)

Published 2026-08-22 · Clinically reviewed 2026-08-22 · Updated 2026-08-23

BV usually causes a thin, greyish discharge with a fishy smell; thrush causes itching and a thick white discharge. How to tell which you have.

The quickest way to tell them apart: bacterial vaginosis (BV) usually means a thin, greyish-white discharge with a distinctive fishy smell and little or no itching, while thrush usually means intense itching and soreness with a thick, white, cottage-cheese-like discharge that barely smells at all. The distinction matters because the treatments do not overlap — BV needs antibiotics, thrush needs antifungals, and using the wrong one leaves the real problem untouched. BV is also the more common of the two, despite thrush having the bigger reputation.

Symptoms side by side

	Bacterial vaginosis	Thrush
Discharge	Thin, watery, grey-white	Thick, white, like cottage cheese
Smell	Fishy, stronger after sex	Little or none
Itching	Uncommon	Prominent, often intense
Soreness or redness	Uncommon	Common, may sting when peeing
Vaginal pH	Raised (above 4.5)	Normal (4–4.5)

Neither condition typically causes pelvic pain, fever or bleeding — those symptoms point elsewhere and need a clinician.

What causes each one?

A healthy vagina is mildly acidic, kept that way by lactobacilli. BV happens when those bacteria fall and mixed bacteria overgrow, pushing pH up. It is not an infection you "catch" so much as an ecosystem shift — triggered by douching or perfumed products, periods, semen (which is alkaline), a new sexual partner, or a copper coil in some women. Thrush is the opposite kind of imbalance: an overgrowth of Candida yeast in a normally acidic environment, encouraged by antibiotics, pregnancy, diabetes, a weakened immune system or damaged skin.

BV is not classed as a sexually transmitted infection, though sex can trigger it. Thrush is not an STI either — both are imbalances of organisms that live there normally.

How is each one treated?

BV is treated with antibiotics: metronidazole tablets (or vaginal gel), or clindamycin cream as an alternative. Avoid alcohol completely during and for 48 hours after metronidazole — the combination causes severe sickness for some people. Thrush is treated with antifungals: a single fluconazole capsule by mouth, or a clotrimazole pessary with cream for external symptoms. Antifungals do nothing for BV, and antibiotics can actively cause thrush by clearing protective bacteria — one reason a wrong guess sometimes produces the other condition a week later.

In pregnancy both conditions still need treating, but the choices change (no oral fluconazole, for instance), so speak to a midwife, GP or pharmacist rather than self-treating.

Can you have both at once?

Yes — the two imbalances can coexist, which produces confusing, mixed symptoms such as an itchy but fishy-smelling discharge. A swab sorts it out quickly. Mixed or ambiguous pictures are exactly when guessing costs the most time.

When should you test rather than guess?

Self-treating a classic, one-off episode is reasonable. Get a proper assessment — GP, sexual health clinic or a pharmacy consultation — if it is your first ever episode, you are pregnant, symptoms do not settle within a week of treatment, they keep returning, you have a new partner or any STI risk, or there is blood, ulcers, pelvic pain or fever. Chlamydia, gonorrhoea and trichomoniasis can all masquerade as "just discharge", and trichomoniasis in particular mimics BV's smell with added soreness. If thrush is the one that keeps returning, our guide to recurrent thrush explains what breaks that cycle.

Why does BV keep coming back?

Recurrence is BV's signature problem — around half of women see it return within months of treatment, because antibiotics clear the overgrowth without always restoring the protective lactobacilli. Repeated episodes justify a review of triggers: douching and perfumed washes (stop completely), whether episodes follow sex with a particular partner (condoms for a while are a useful experiment, since semen raises pH), and period patterns. For confirmed frequent relapses, clinicians can prescribe suppressive courses such as twice-weekly metronidazole gel.

Looking after your vaginal microbiome

The vagina is self-cleaning: wash the vulva with water or a plain emollient, never douche, and keep soaps, wipes, deodorants and "intimate washes" away from it — perfumed products are the biggest self-inflicted trigger for both conditions. Cotton underwear, prompt changes out of wet kit, and liners only when genuinely needed all help the skin. Evidence for probiotics remains mixed; none of them replaces treatment.

Frequently asked questions

Is BV a sexually transmitted infection?

No, although sex — especially without condoms, or with a new partner — can trigger the pH shift that lets it develop. Male partners do not need treatment.

Will BV or thrush go away on their own?

Mild BV sometimes settles as the cycle moves on, and mild thrush can too, but both tend to linger or relapse untreated — and in pregnancy BV deserves treatment because it carries pregnancy risks. If symptoms are clear, treat them.

Can men get thrush or pass it back?

Men can occasionally get penile thrush (itchy red rash, usually after antibiotics or with diabetes), but ping-pong reinfection between partners is rare and routine partner treatment is not recommended for either condition.

Does a smelly discharge always mean BV?

No — trichomoniasis and a forgotten tampon are two other causes of strong-smelling discharge. A fishy smell with a thin grey discharge is BV's classic pattern, but anything persistent or unusual deserves a swab.

If your symptoms match one pattern clearly, treatment can be quick: you can check your eligibility for BV treatment online, and a UK clinician will confirm whether antibiotics, antifungals or an in-person review is the right next step.