HIV isn't passed on EVERY time unprotected sex happens but it could be passed on ANY time it happens. The risk depends on the following:

What kind of sex
The kind of unprotected sex you have can make a big difference. For example, oral sex is less risky than vaginal sex, which is less risky than anal sex.

Man or a woman.
It's easier for women to get infected (although millions of African men also been infected). If a man has HIV his semen (with the virus in it) is left inside the woman's vagina for a long time, giving HIV more chance to enter her bloodstream. If a woman has HIV it's harder for her body fluids (e.g., vaginal fluid or blood) to get into the man's body through his penis.

Damage during sex
Friction during sex can cause small cuts inside the vagina or on the skin of the penis. The damage can be too small for you to see it but it allows HIV to pass from one body to another.

The amount of HIV inside the body.
People recently infected have a very high level of HIV in their body, making it easier for them to pass on HIV. If a positive person is taking HIV medicines, that usually means less HIV in their body, so they are less likely to infect others.

Ejaculation
The risk of a man infecting someone is greater if he ejaculates inside them. If he pulls out before he ejaculates, the risk is lower (although infection could still happen).

Other illnesses
If an HIV negative person has an illness (e.g. a sexually transmitted infection, TB or malaria) then their immune system is under attack already, so is less able to protect them from getting HIV. If an HIV positive person has another illness, this weakens their immune system even more, leading to higher levels of HIV in their body. This makes it easier for them to pass on HIV.

Circumcision
Studies have shown that circumcised men are less likely to get HIV. Removing the foreskin – which can be easily damaged during sex – makes the tip of the penis tougher and harder for HIV to get through.
But if a circumcised man has HIV this does NOT make him less likely to infect a woman.

All of the things I’ve mentioned above may reduce the risk of HIV infection but none are guaranteed to protect you or your partner. Condoms are the best protection against HIV (and other sexually transmitted infections). If you’d like to talk in confidence to someone about how HIV is passed on you can call the African AIDS Helpline on 0800 0967500 or THT Direct on 0845 1221 200.

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