Thrush is a yeast infection caused by a fungus called Candida albicans. Both men and women can get thrush, though it is more often associated with women.
The medical term for thrush is candidiasis.
In men, it usually affects the head of the penis – causing irritation, discharge and redness.
Read more about the symptoms of thrush
It can also affect the skin, known as candidal skin infection, and the inside of the mouth, known as oral thrush.
If you suspect thrush for the first time, it's best to see a doctor for a diagnosis. This is because the symptoms can be similar to those of a sexually transmitted infection (STI). Your GP will be able to tell the difference.
If you've had thrush before and you recognise the symptoms, you can treat it yourself with over-the-counter medication.
You should also visit your GP if you have a weakened immune system and you have thrush. This is because there is a risk that a thrush infection could progress to a more serious case of invasive candidiasis. Read our page on the complications of thrush for more information about invasive candidiasis.
You can treat thrush without prescription medications. For thrush affecting your penis, ask your chemist for clotrimazole cream or a tablet called fluconazole. For thrush infections in your groin or elsewhere, the chemist can supply a cream.
It's possible for thrush to spread during sex, but it's not an STI. However, both sexual partners may need thrush treatment to prevent re-infection. Re-infection from a female partner is common. Seek advice from a pharmacist or your GP.
However, not all cases are caused by sex, and many cases develop in men and women who are not sexually active.
Read more about treating thrush
You can help prevent thrush by cleaning your penis regularly and using a condom while having sex with your partner (if they have thrush).
Avoid using perfumed soaps or shower gels on your genitals, as they can cause irritation. Make sure you dry your penis properly after washing.
Wearing loose-fitting cotton underwear can help prevent moisture building up under your foreskin, which lowers the chances of the candida fungus multiplying.
The fungus candida albicans occurs naturally in your body, particularly in warm, moist areas, such as inside the mouth and around the genitals.
It does not usually cause problems because it is kept under control by your immune system (the body’s natural defence against illness and infection) and other types of bacteria in the body.
However, certain conditions can cause the fungus to multiply and lead to infection. You are more likely to be at risk of thrush if: