Thrush and bacterial vaginosis (BV) are the two most common vaginal infections. They are often confused, and the treatment for one will not work for the other, so knowing the difference helps you get the right treatment faster.
What Is Normal?
A healthy vagina produces discharge, which keeps it clean and protected. It is usually clear or white and changes in amount and texture across the menstrual cycle, becoming clearer and stretchier around ovulation. The vagina is home to helpful bacteria, mainly a type called lactobacilli, which keep it slightly acidic and help protect against infection. It cleans itself, so washing inside it, known as douching, is unnecessary and can upset this balance.
Thrush
Thrush is caused by an overgrowth of a yeast called Candida, which normally lives in the body without causing problems. Around 3 in 4 women will have thrush at least once. Typical signs include:
Itching and soreness around the vagina and vulva
Thick white discharge, often described as looking like cottage cheese, with little or no smell
Stinging when you pass urine or during sex
Thrush is treated with antifungal medicine, either as a tablet or as a cream or pessary, a tablet placed inside the vagina. It is not considered a sexually transmitted infection, and partners do not usually need treatment. If you have thrush four or more times a year, see a doctor rather than treating it yourself each time, as you may need tests and a longer course of treatment.
Bacterial Vaginosis (BV)
BV happens when the balance of bacteria in the vagina changes, with fewer protective lactobacilli and more of other types. It is the most common cause of unusual discharge in women of reproductive age. Typical signs include:
Thin grey or white discharge
A fishy smell, often stronger after sex or during a period
Usually little itching or soreness
BV is treated with antibiotics, usually metronidazole or clindamycin. Treatment works well in the short term, but BV comes back in more than half of women within a year. Left untreated, BV can raise the risk of some sexually transmitted infections and, in pregnancy, of an early birth.
New Research on Stopping BV Coming Back
For a long time, BV was not thought of as sexually transmitted. A trial published in 2025 in the New England Journal of Medicine changed that view. Women with BV were treated alongside their regular male partners, who took antibiotic tablets and applied an antibiotic cream to the penis for a week. Over 12 weeks, BV came back in 35 per cent of women whose partners were treated, compared with 63 per cent of women whose partners were not. The difference was so clear that the trial was stopped early.
This suggests that BV can be passed between partners. If your BV keeps coming back and you have a regular male partner, ask your doctor whether treating your partner is an option. It is not yet standard practice everywhere, and research in women with female partners is still needed.
Reducing Your Risk
Avoid douching, and avoid scented products such as washes or wipes around the vagina
Wash the vulva with plain water or a gentle unscented cleanser
Use condoms with new partners, which may lower the risk of BV
Avoid unnecessary antibiotics, which can trigger thrush in some women
Probiotic products for vaginal health are widely sold, but the evidence that they prevent thrush or BV is limited.
When to See a Doctor
See a doctor or pharmacist if it is your first time with these symptoms, if you are pregnant, if treatment has not worked or if symptoms keep coming back. Some sexually transmitted infections cause similar symptoms, so testing is worthwhile, especially if you have a new partner.