gynecology
Vaginal Infections: Bacterial Vaginosis, Yeast, and How to Tell Them Apart
These two are constantly mistaken for each other, and it matters, because they are treated with completely different medicines. An antifungal will do nothing for bacterial vaginosis, and studies of women buying over-the-counter thrush treatment have repeatedly found that most of them did not have thrush.
If you have treated yourself twice and it has not worked, stop guessing and get tested.
Telling them apart
Bacterial vaginosis (BV) — an imbalance in which the normally dominant lactobacilli are crowded out by other bacteria.
- Thin, greyish-white, watery discharge
- A fishy odour, characteristically worse after sex or during your period
- Usually little or no itching
- Often no irritation at all — odour is the complaint
Yeast infection (vulvovaginal candidiasis) — an overgrowth of Candida.
- Thick, white, clumpy discharge, often compared to cottage cheese
- Intense itching — the dominant symptom
- Redness, swelling, soreness of the vulva
- Burning with urination or sex
- No strong odour
Rough rule: itch without odour points to yeast; odour without itch points to BV. But the overlap is real, you can have both at once, and neither is reliably diagnosed by yourself.
Why BV matters more than people think
BV is often dismissed as a nuisance. It is associated with:
- Increased susceptibility to HIV and other STIs
- Preterm birth and late miscarriage in pregnancy
- Pelvic inflammatory disease after gynecologic procedures
- Post-surgical infection
That is why it is worth treating properly rather than masking, and worth mentioning to your provider if you are pregnant.
What causes them
BV risk rises with: new or multiple sexual partners, douching, smoking, and an IUD in some people. BV is not classed as an STI — it occurs in people who have never been sexually active — but sexual activity changes the vaginal environment and clearly influences it.
Yeast risk rises with: recent antibiotics (the most common trigger), diabetes or poor glycaemic control, pregnancy, immunosuppression, and high-dose estrogen. Tight non-breathable clothing and staying in wet swimwear play a smaller role than the internet suggests.
Treatment
Bacterial vaginosis
Requires antibiotics, prescribed:
- Metronidazole — oral for 7 days, or vaginal gel for 5
- Clindamycin — vaginal cream, an alternative
- Secnidazole or tinidazole — single-dose oral options
Finish the course even when symptoms settle early. Recurrence is common — up to half within a year — and recurrent BV is managed with longer suppressive regimens, so say so rather than re-treating repeatedly on your own.
Treating male partners has not been shown to prevent recurrence in most studies, though this is an area of active research.
Yeast
- Fluconazole — a single oral dose, usually enough for uncomplicated cases
- Topical azoles — clotrimazole or miconazole, 1 to 7 days, available over the counter
- Recurrent thrush (four or more a year) needs a longer induction-and-maintenance course over several months, and a check for undiagnosed diabetes
- Non-albicans species resist standard treatment and need a culture to identify
In pregnancy, topical azoles are used; oral fluconazole is generally avoided, particularly in the first trimester. Do not self-treat while pregnant without asking.
What does not work
- Douching. It makes BV more likely, not less, by stripping the lactobacilli you need. The vagina is self-cleaning. Wash the vulva with water; nothing goes inside.
- Scented washes, wipes, bubble baths, and "feminine hygiene" products — a common cause of irritation that then gets mistaken for infection.
- Boric acid has a genuine evidence base for recurrent and resistant cases, but only under medical guidance — and it is toxic if swallowed, which is worth knowing if there are children in the house.
- Probiotics and yoghurt — the evidence is weak and inconsistent. Not harmful; not a treatment.
When it is neither
Discharge is not always infection. Get evaluated rather than self-treating if you have:
- Green, yellow, or frothy discharge — think trichomoniasis, which is an STI and needs specific treatment
- Bleeding between periods or after sex
- Pelvic or abdominal pain, fever, or pain with sex — possible PID
- Sores, blisters, or ulcers
- Symptoms that persist after correct treatment
- Recurrent infections
- Any symptoms in pregnancy
Normal discharge changes across the cycle — clear and stretchy around ovulation, thicker afterwards. That is physiology, not a problem to fix.
Testing
A simple examination with vaginal pH, microscopy, and where needed a culture or NAAT settles what you have in one visit. It is quick, and it replaces months of alternating between the wrong products.
Talk to us
Medical disclaimer
This article is general health information, not medical advice for any individual. Vaginal symptoms have several causes that look alike and are treated differently; testing is what distinguishes them. Symptoms in pregnancy, with pelvic pain, or with fever should be assessed promptly.