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Is It Thrush, BV or Something Else? A Decision Table
Thrush itches and gives a thick white discharge with little smell; bacterial vaginosis (BV) gives a thin grey-white discharge with a fishy smell and rarely itches; trichomoniasis is frothy, yellow-green and sore; cystitis is a bladder problem, with stinging when you pee and no discharge. Textbook pictures; in practice, when 95 women buying an over-the-counter thrush treatment were examined, 34% had thrush alone, 19% BV alone, 21% both and 14% nothing wrong.1, 2 The misses that cost years are not infections: lichen sclerosus, atrophy after the menopause, an allergy to the cream itself. This is the symptom spoke of the Wellgard guide to what causes BV.
Is it thrush, BV or something else? The decision table
| Cause | Discharge | Smell | Itch and soreness | Other clues | Who to see |
|---|---|---|---|---|---|
| Thrush (candida) | Thick, white, like cottage cheese; sometimes none | Little or none | Itch is the main symptom; soreness, stinging when you pee or during sex; redness | After antibiotics, in pregnancy, with diabetes; pH stays below 4.5 | Pharmacist if diagnosed before; GP if first time, under 16 or over 60, pregnant, or needed twice in six months1 |
| Bacterial vaginosis | Thin, watery, grey or white, often heavier | Fishy, worse after sex and around a period | Usually none; no redness | After a period, sex, douching or a copper coil; pH above 4.5; half have no symptoms3 | GP or sexual health clinic; antibiotics are prescription-only |
| Trichomoniasis (an STI) | Frothy, yellow-green, often heavy | Fishy or unpleasant | Soreness, itch, swelling; pain when you pee or during sex | New or untreated partner; many women have no symptoms4 | Sexual health clinic; partners need treatment as well |
| Cystitis or UTI | None | Urine strong-smelling or cloudy | Burning when you pee, urgency, frequency, lower tummy ache | After sex or the menopause; blood or fever means a GP that day5 | Pharmacist (women 16 to 64); GP or 111 with red flags |
| Vaginal atrophy (after the menopause) | Scant; sometimes thin and yellowish | Sometimes "musty"; pH rises | Dryness, burning, soreness, pain during sex; antifungals do nothing | Perimenopause onwards, breastfeeding; repeated UTIs6 | GP or pharmacist; vaginal oestrogen is the usual conversation |
| Lichen sclerosus | None | None | Relentless vulval itch, often at night; white shiny or crinkled patches; splits, pain during sex | Commonest over 50 but any age; skin that tears easily; "thrush for years" that no cream helped7 | GP, then dermatology or a vulval clinic; prescription steroid ointment |
| Contact dermatitis or cream allergy | None | None | Itch, burning and redness of the vulva that worsen after each cream, wipe, pad or wash | Starts or flares after a new product, including the thrush cream itself | GP; stop every product except water and an emollient |
| Cytolytic vaginosis | White, sometimes thick, like thrush | None or sour | Itch and burning, often worse before a period | Thrush swabs keep coming back negative; pH low; lactobacilli over-abundant8 | GP or gynaecology; diagnosis by microscopy |
| Retained tampon or condom | Heavy, brown or discoloured | Very strong, foul | Discomfort; fever or pelvic pain needs same-day care | A period a week or two ago; a tampon you are not sure came out | GP, sexual health clinic or 111 that day |
How can you tell if it's thrush?
By the itch more than the discharge. In a review of studies that tested symptoms against laboratory diagnosis, no single symptom confirmed any cause, but the absence of itching made thrush unlikely and the absence of a smell made BV unlikely.2 The NHS lets a pharmacist sell an antifungal to a woman who has had thrush diagnosed before, and not more than twice in six months without seeing a pharmacist or doctor.1 A second pack inside six months means a swab, not a third pack. Vaginal thrush: symptoms, causes and treatment and what causes thrush cover the condition and its triggers.
What is usually mistaken for BV, and what does BV get mistaken for?
BV is mistaken for thrush far more often than thrush is mistaken for BV: in the thrush-aisle study, BV or a mixed picture accounted for 40% of the women.2 BV is also mistaken for poor hygiene and for an STI (it is neither, though sex triggers it), and for ordinary smells: semen, sweat, the first day of a period and urine leakage each have a smell, none of them fishy. "How do I know if I have BV or just a smell?" A thin grey discharge with a smell that is worst after sex is probably BV; a smell that comes and goes with sweat, exercise or the end of a period, with no change in discharge, probably is not. What does BV discharge look like? and Does BV always have a smell? take each sign in turn.
How do I know if it's BV or trichomoniasis?
Often you cannot without a swab. Trichomoniasis is a sexually transmitted parasite; the NHS describes a yellow-green discharge that may be frothy or fishy, with itching, soreness, swelling and pain when you pee or have sex.4 BV usually brings no soreness and no redness. The two also travel together: in a 2021 meta-analysis of 12 studies, women with BV were about 1.9 times as likely to acquire trichomoniasis.9 A sexual health clinic tests for both from one swab, and for trichomoniasis your current and recent partners need treatment too.4
How can I tell the difference between BV, thrush and a UTI?
By where it hurts. Cystitis is a bladder infection: burning as you pee, going often and urgently, lower tummy ache, and no vaginal discharge.5 Thrush stings as urine passes over sore skin, which women read as cystitis; the giveaway is that the stinging is outside, with itch and discharge. BV gives discharge and smell with no urinary symptoms. The UTI red flags: fever, shivering, back or side pain, blood in the urine, being sick, confusion in an older woman, pregnancy, or no improvement after 48 hours mean a GP or 111 the same day, and 999 for signs of sepsis.5 Cystitis: everything you need to know covers the rest.
What could be mistaken for thrush when it isn't an infection at all?
Four things. Vaginal atrophy, now called the genitourinary syndrome of menopause: falling oestrogen thins the vaginal skin, the lactobacilli fall away and the pH rises, giving dryness, burning, soreness, pain during sex and repeated UTIs; it can start in perimenopause and while breastfeeding, and no antifungal helps it.6 Vaginal health after the menopause covers it. Lichen sclerosus: an inflammatory skin condition with a relentless itch and white smooth or crinkled patches that tear easily; the NHS says it cannot be cured but a prescription steroid ointment usually relieves it, and because it slightly raises the risk of vulval cancer it is checked regularly.7 Contact dermatitis: the vulval skin reacts to a wipe, a pad, a wash or the antifungal cream itself, so each treatment makes the itch worse; the test is to stop everything but water and a plain emollient. Cytolytic vaginosis: a contested diagnosis in which lactobacilli are over-abundant and the discharge is white and itchy, so it looks like thrush but swabs are negative; a 2023 review found it reported in about 5% of women with vaginal symptoms, diagnosed by microscopy, with no agreed treatment.8 The common thread is a negative swab, which is information, not a dead end.
When should I stop self-treating and see a GP or sexual health clinic?
When thrush treatment has not worked within a week, or you have needed it twice in six months.1 For a first episode of anything. For bleeding between periods, after sex or after the menopause. For sores, blisters, white patches, splits or any skin change. For pelvic pain, fever or pain during sex. For symptoms in pregnancy. For a new partner, with an STI test. For a first episode under 16 or over 50. For BV more than four times a year. And for a smell that does not go. Sexual health clinics need no referral, and the NHS vaginal discharge page says plainly not to self-diagnose.3, 10
How do a swab, pH test and culture settle it?
A clinician looks, dips a pH strip into the discharge (BV and trichomoniasis push the pH above 4.5; thrush and cytolytic vaginosis leave it low) and puts a drop under the microscope: clue cells mean BV, yeast cells and threads mean thrush, moving parasites mean trichomoniasis, and sheets of lactobacilli with fragmented cells suggest cytolytic vaginosis.2, 8 The review that compared these tests with symptoms concluded that microscopy, not the story, is the most useful way to diagnose the three infections.2 A culture names the yeast species when thrush keeps returning, since some species resist the usual antifungals. If every swab is negative and the skin is the problem, the next stop is a dermatologist or vulval clinic.7
Frequently asked questions
What happens if you use a thrush cream but you have BV?
Nothing useful: antifungals do not act on bacteria, so the discharge and smell carry on and the cream can irritate. Antibiotics for BV are prescription-only; how BV is treated in the UK covers the routes.
What smells like BV but isn't BV?
Trichomoniasis, a retained tampon (a far stronger, foul smell), semen for a day after sex, the end of a period, and urine leakage after the menopause. Only a swab tells BV from trichomoniasis.4
How can I be sure I have thrush?
Only a swab is sure. Itch with a thick white discharge and no smell makes it likely; a first episode, a pregnancy or a second episode within six months means a swab rather than a pharmacy pack.1, 2
What is the treatment for an infection "down there"?
It depends which one: an antifungal pessary, cream or tablet for thrush; a prescription antibiotic for BV and trichomoniasis; steroid ointment for lichen sclerosus; vaginal oestrogen for atrophy, a GP or pharmacist conversation. No single product covers them, which is why the diagnosis comes first.1, 3, 4, 5, 7
Sources
- NHS. Thrush in men and women. nhs.uk/conditions/thrush-in-men-and-women.
- Ferris DG, et al. Over-the-counter antifungal drug misuse associated with patient-diagnosed vulvovaginal candidiasis. Obstetrics and Gynecology, 2002. PubMed 11864668; Anderson MR, Klink K, Cohrssen A. Evaluation of vaginal complaints. JAMA, 2004. PubMed 15026404.
- NHS. Bacterial vaginosis. nhs.uk/conditions/bacterial-vaginosis.
- NHS. Trichomoniasis. nhs.uk/conditions/trichomoniasis.
- NHS. Urinary tract infections (UTIs). nhs.uk/conditions/urinary-tract-infections-utis.
- Portman DJ, Gass MLS. Genitourinary syndrome of menopause: new terminology for vulvovaginal atrophy. Menopause, 2014. PubMed 25160739.
- NHS. Lichen sclerosus. nhs.uk/conditions/lichen-sclerosus.
- Kraut R, et al. Scoping review of cytolytic vaginosis literature. PLoS One, 2023. PubMed 36701339.
- Seña AC, et al. Bacterial vaginosis and its association with incident Trichomonas vaginalis infections: a systematic review and meta-analysis. Sexually Transmitted Diseases, 2021. PubMed 34433796.
- NHS. Vaginal discharge. nhs.uk/conditions/vaginal-discharge.
This article is general information, not medical advice. A first episode, treatment that has not worked, bleeding, skin changes, pain, fever, pregnancy or symptoms over 50 mean a GP or sexual health clinic rather than self-treatment.
