Thrush and bacterial vaginosis
Both are common, both cause changes in discharge, and they are treated with entirely different medicines. Self diagnosis is wrong often enough that repeated treatment without a test is a poor strategy.
Telling them apart
| Feature | Thrush | Bacterial vaginosis |
|---|---|---|
| Main symptom | Itching and soreness | Odour and changed discharge |
| Discharge | Thick, white, often described as like cottage cheese | Thin, grey or white, homogeneous |
| Smell | Little or none | Distinctive fishy smell, often stronger after sex or during a period |
| Itching | Usually prominent | Usually absent |
| Soreness with sex | Common | Less common |
| Cause | Overgrowth of yeast normally present in small numbers | Reduction in protective lactobacilli and overgrowth of other bacteria |
| Usual treatment | Antifungal, as a cream, pessary or tablet | Antibiotic, as a gel or tablet |
Trichomonas, which is a sexually transmitted infection, causes a frothy yellow green discharge with soreness and can be mistaken for either. That is one reason a test matters when symptoms are new, recurrent or accompanied by pain.
Thrush
What happens
Yeast, usually candida, lives harmlessly in small numbers in many people. Thrush occurs when it multiplies. Factors that make that more likely include recent antibiotics, pregnancy, poorly controlled diabetes, a weakened immune system, and, for some people, hormonal changes across the cycle. Contrary to common belief, thrush is not caused by poor hygiene, and over washing makes it more likely rather than less.
Symptoms
Itching, soreness, a thick white discharge that does not usually smell, redness and swelling of the vulva, discomfort when passing urine where the skin is inflamed, and pain with sex. Splitting of the skin can occur with severe episodes.
Treatment
Antifungal treatment is effective, available as a pessary, an internal cream, an external cream for the itching, or an oral capsule. A first episode with typical symptoms can reasonably be treated on the basis of the symptoms, particularly with pharmacy advice. Recurrent episodes should be confirmed with a swab before repeating treatment.
Recurrent thrush, usually defined as four or more confirmed episodes in a year, is managed with a longer course rather than repeated short ones, and warrants investigation for an underlying cause including diabetes.
What does not help
Douching, antiseptic washes, and applying yoghurt internally are not effective treatments and irritation from them can prolong symptoms.
Bacterial vaginosis
What happens
The vagina is normally dominated by lactobacilli, which keep the environment acidic. In bacterial vaginosis these are reduced and other bacteria increase, raising the pH. It is the commonest cause of changed vaginal discharge and around half of those affected notice no symptoms at all.
Factors associated with it include douching, new or multiple sexual partners, semen exposure because it is alkaline, smoking, and use of scented products. It is not caught from a partner in the way an infection is, and female partners are sometimes treated where symptoms recur.
Symptoms
A thin grey or white discharge, a distinctive fishy odour that is often more noticeable after sex or during a period, and generally no itching or soreness. Pain and itching suggest something else, or something else in addition.
Treatment
Antibiotic treatment, as a tablet course or a vaginal gel, is effective. Treatment is recommended for symptomatic infection and for some situations in pregnancy, since bacterial vaginosis in pregnancy is associated with an increased risk of preterm birth.
Recurrence is common and frustrating. Reducing modifiable factors helps: stop douching entirely, stop using scented products and washes, and use condoms for a period if symptoms consistently follow sex. Longer suppressive courses are used in some services for frequent recurrence. Evidence for probiotic products is mixed and they are not a substitute for treatment. See the vaginal microbiome.
When to test rather than treat
- Symptoms that are new and have not been diagnosed before.
- Symptoms that recur, since studies of self diagnosis show it is frequently wrong.
- Any pain, fever or pelvic pain, which suggests something more than either condition.
- Bleeding between periods or after sex.
- Symptoms during pregnancy.
- Symptoms after a new partner, when testing for sexually transmitted infections is also appropriate. See testing for sexually transmitted infections.
- Two courses of treatment that have not worked, which is a reason to look for a different diagnosis such as lichen sclerosus, vulvodynia or an irritant reaction.
Normal discharge
Some discharge is normal and healthy. It changes through the cycle, becoming clearer and more stretchy around ovulation and thicker afterwards, and it varies with hormonal contraception and pregnancy. Normal discharge is not accompanied by itching, pain, a strong smell or blood. Attempting to eliminate it with washes or douches is the single most reliable way to cause a problem that was not there.
Where this information comes from
This page follows public guidance and patient information published by the National Health Service, the National Institute for Health and Care Excellence, the World Health Organization, and the Royal College of Obstetricians and Gynaecologists.
Last reviewed: September 2026