The fungus candida albicans occurs naturally in your body, particularly in warm, moist areas, such as inside the mouth and around the genitals.  It is quite normal to have some yeast present in the genital area but a range of factors can cause this natural yeast to overgrow. Whilst thrush is a problem often more associated with cis-women, anyone can get thrush.

It's possible for thrush to spread during sex, but it's technically not an STI.  

Symptoms can include redness, rash, or itching on the part of the body infected.

Thrush can appear in your mouth, your penis, and sometimes in your anus. It is not an STI but it is sometimes related to sex.

If you suspect thrush for the first time, it's best to see your GP 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 can help prevent thrush by regularly using condoms, cleaning your penis (with water only) and drying under the foreskin daily and particularly after washing.  

Avoid using perfumed soaps or shower gels on your genitals, as they can cause irritation.

It may also help to wear light cotton underwear and avoid tight restrictive clothing to prevent moisture building up under your foreskin, which lowers the chances of the candida fungus multiplying.

Thrush can be more common and more severe for people with HIV. Some oral anti-fungal treatments can interact badly with HIV meds, so always check with your HIV doctor before taking them.