What does that mean to me?

You don't need to sleep around to get an STI - anyone who has sex without a condom is at risk.

HIV is the most dangerous STI simply because there is no cure. It weakens the immune system so that your body finds it harder to fight off other infections.

Green ooze dripping out of your penis or vagina can be a symptom of gonorrhoea, but many STIs don't carry any symptoms at all, though they can lead to infertility, heart disease, brain and nervous system damage.

Chlamydia is now the most common (yet easily curable) STI in the UK - as many as one in ten young people under 25 may be infected with it. Often people don't know they have it as there aren't always symptoms, but an infection could leave you unable to have children.