Thrush vs BV vs Trichomoniasis: Discharge Compared
Three conditions, three different treatments, and three questions that tell them apart — itch, smell and the look of the discharge, plus the one test that settles it.
Part of the Complete Thrush Guide.
Key fact: Thrush itches and does not smell. BV smells and does not itch. Trichomoniasis is frothy, yellow-green and sexually transmitted, so it needs testing and partner treatment. Vaginal pH separates them more reliably than symptoms: normal in thrush, raised in the other two.
Why getting it right matters
These three conditions account for the great majority of abnormal vaginal discharge, and they need three different treatments: an antifungal for thrush, an antibiotic for bacterial vaginosis, and a specific antibiotic course plus partner treatment for trichomoniasis, which is a sexually transmitted infection.
Treating the wrong one costs a week and leaves the real problem untreated. Studies of self-diagnosis consistently find a substantial proportion of women who believe they have thrush have something else — which is why the comparison below is worth five minutes before buying anything.
The three compared
| Thrush | Bacterial vaginosis | Trichomoniasis | |
|---|---|---|---|
| Cause | Candida yeast overgrowth | Loss of Lactobacilli, overgrowth of anaerobic bacteria | Trichomonas vaginalis, a parasite — sexually transmitted |
| Discharge | Thick, white, cottage-cheese-like | Thin, watery, grey or white | Frothy, yellow-green, often heavier |
| Smell | None | Fishy, worse after sex | Unpleasant, sometimes fishy |
| Itching | Intense — the hallmark | Usually absent or mild | Soreness, itching and irritation |
| Vaginal pH | Normal, below 4.5 | Raised, above 4.5 | Raised, above 4.5 |
| Other features | Vulval redness, stinging as urine passes over the skin | Often no soreness at all | Pain passing urine, lower abdominal discomfort, vulval swelling |
| Treatment | Fluconazole or clotrimazole | Metronidazole, or clindamycin | Metronidazole — and partners must be treated |
| Partner treatment | Not routinely | Not routinely | Yes, always |
| Where to go | Pharmacy or GP | Pharmacy or GP | Sexual health clinic or GP — needs testing |
The three questions that separate them
1. Does it itch?
Intense itching points strongly to thrush. BV characteristically does not itch, which surprises people. Trichomoniasis causes soreness and irritation more than pure itch.
2. Does it smell?
Thrush does not smell. A distinct fishy odour, particularly one that worsens after sex, points to BV or trichomoniasis, not thrush.
3. What is the discharge like?
Thick and white means thrush. Thin, watery and grey means BV. Frothy and yellow-green means trichomoniasis and needs testing.
And one test
Vaginal pH separates them more reliably than any symptom: normal in thrush, raised in both BV and trichomoniasis. A pH self-test is available over the counter.
Our guide to using a self-test covers what the result does and does not tell you. It is good at distinguishing thrush from the other two; it does not identify trichomoniasis specifically, which needs a swab.
Thrush in brief
Candida overgrowth, not sexually transmitted, extremely common. Itching with thick odourless white discharge, treated with a single fluconazole capsule or topical clotrimazole — see fluconazole vs Canesten. Four or more episodes a year is recurrent thrush and is managed differently. Frequently follows a course of antibiotics.
Bacterial vaginosis in brief
A shift in vaginal bacteria rather than an infection caught from someone, and the most common cause of abnormal discharge in women of reproductive age. Thin grey discharge with a fishy smell, usually without itching. Treated with metronidazole or clindamycin — see understanding BV and BV treatment options. It matters in pregnancy because BV has been associated with preterm birth, so it is treated rather than tolerated.
Trichomoniasis in brief
The one of the three that is a sexually transmitted infection. It is caused by a parasite, produces frothy yellow-green discharge with soreness and pain passing urine, and often causes no symptoms at all — in either partner. Diagnosis needs a swab, treatment is metronidazole (as a course or a single larger dose), and partners must be treated regardless of symptoms, with sex avoided until treatment is complete.
If trichomoniasis is possible, get tested rather than treated blind. It is diagnosed on a swab, it usually comes with a recommendation to test for other sexually transmitted infections at the same time, and partner notification is part of treatment. A sexual health clinic can do all of that in one visit, free and confidentially.
When it is none of the three
If the discharge is normal and itching is the only symptom, or if antifungals have already failed, widen the differential: vulval eczema and contact dermatitis from soaps, wipes or pads; lichen sclerosus, which produces white thickened skin and needs specialist assessment; and after the menopause, atrophic change from falling oestrogen, which causes itching and dryness without infection at all.
See a clinician promptly for bleeding between periods or after sex, pelvic or abdominal pain, fever, ulcers or sores, discharge with a recent new partner, or any symptoms in pregnancy. Chlamydia and gonorrhoea can cause discharge with few other symptoms, and neither responds to anything sold for thrush.
Frequently Asked Questions
How do I know if I have thrush or BV?
Three questions separate them. Thrush itches intensely; BV usually does not. Thrush does not smell; BV has a distinct fishy odour that worsens after sex. Thrush discharge is thick and white; BV discharge is thin, watery and grey. If you are still unsure, vaginal pH is the most reliable single test — normal in thrush, raised in BV.
What does trichomoniasis discharge look like?
Classically frothy, yellow-green and heavier than usual, with an unpleasant smell, soreness and sometimes pain passing urine. Many people have no symptoms at all, which is one reason it is often missed. Unlike thrush and BV, it is a sexually transmitted infection, so it needs a swab to diagnose and partner treatment as part of the cure.
Can you have thrush and BV at the same time?
Yes, and it is not rare. Mixed infection is one reason symptoms can be confusing and why treating one condition only partly helps. If symptoms improve but do not resolve after treating one, go back rather than repeating the same treatment — a clinical assessment can identify both.
Does a pH self-test tell me which infection I have?
It distinguishes thrush from the other two reasonably well, because vaginal pH stays normal in thrush and rises in both bacterial vaginosis and trichomoniasis. What it cannot do is tell BV and trichomoniasis apart, or rule out a sexually transmitted infection. A raised pH is a reason to seek assessment rather than to buy an antifungal.
Do I need to tell my partner?
For trichomoniasis, yes — partners must be treated even without symptoms, and sex should be avoided until treatment is finished. For thrush and bacterial vaginosis, routine partner treatment is not recommended and has not been shown to prevent recurrence, though a partner with symptoms should be assessed in their own right.
What if it is none of these?
Consider the non-infectious causes. Vulval eczema or contact dermatitis from soaps, wipes and pads causes itching with no abnormal discharge. Lichen sclerosus produces white, thickened skin and needs specialist assessment. After the menopause, falling oestrogen causes itching and dryness without any infection. Persistent symptoms that have not responded to treatment should be examined rather than treated again.
References
- NHS. Thrush in men and women. nhs.uk
- NHS. Fluconazole: how and when to take it. nhs.uk
- National Institute for Health and Care Excellence. Clinical Knowledge Summary: Candida — female genital. cks.nice.org.uk
- British Association for Sexual Health and HIV. Guidelines on the management of vulvovaginal candidiasis. bashh.org
- NHS. Bacterial vaginosis. nhs.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Vaginal and genital symptoms have several possible causes and thrush is only one of them. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.