How HIV is passed on

HIV is found in the body fluids of an infected person. Only some fluids have enough HIV in them to infect someone. In men these fluids are:

• blood
• cum
• pre-cum.

There's also enough HIV to pass on the infection in anal mucus (the coating of the inside of the arse).

Spit, sweat and piss don't have enough HIV in them to infect someone.

HIV is usually spread:

• when, during sex, an infectious body fluid gets from a person with HIV into the body, and then bloodstream, of an uninfected person
• when people who inject drugs or steroids share injecting equipment which is carrying infected blood.

HIV isn't as infectious as most other sexually transmitted infections. HIV isn't automatically passed on every time unsafe sex happens, but it could be passed on any time it happens. It's more likely to be passed on the higher someone's viral load is. Your viral load is how much of the virus is in your body - and this can change depending on your treatment, how long it is since you caught the virus, and whether you have any other STIs.

Anal sex (fucking)

HIV is usually passed on sexually between men when they fuck without condoms, thought the risks vary according to which man has HIV:

• A man with HIV fucking an uninfected man is more likely to pass on HIV.
• An uninfected man fucking a man with HIV is less likely to pass on HIV, but it can still happen.
• HIV is more likely to be passed on if a man with HIV comes inside an uninfected man.

How HIV is passed on during fucking

HIV in cum

Infected cum getting in the arse carries the highest risk. If a man with HIV fucks an uninfected man and comes inside him, virus in his cum can get into the other man's bloodstream through the lining of the arse as this lining easily absorbs the cum with HIV in it. Even if the man doing the fucking pulls out before he comes, his infected pre-cum can still pass on HIV to the other man.

HIV and the lining of the arse

When a man is being fucked, the lining of his arse can tear a little and bleed. Bleeding in the arse makes it easier for HIV to be passed on, no matter which man has HIV or who's being fucked.

HIV can also be in the mucus that lines the arse of a man with HIV. A man's dick touching this mucus during fucking gives HIV a chance to get into his bloodstream through the delicate skin in his urethra (the pipe in his dick that piss comes down), foreskin or head of the cock.

HIV and the cock

During anal sex HIV can get into the cock of the man doing the fucking by entering through:

• the delicate, easily torn skin of his foreskin
• the spongy, absorbent head of his cock
• his urethra (piss pipe).

Oral sex (sucking)

It's not clear how many gay men have got HIV from oral sex, but it does happen. We know the vast majority of gay men with HIV got it from unprotected fucking, with a smaller number getting it from sucking.

If you don't have HIV

These will reduce the risk during oral sex:

• keeping cum out of your mouth
• keeping your mouth in good shape
• avoiding oral sex if your mouth or throat is sore, damaged or infected
• paying regular visits to a genito urinary medicine (GUM) clinic to get checks for STIs in your mouth or throat
• if your gums bleed badly, avoiding brushing teeth before sex
• not sucking a cock that has cuts or sores on it
• using a condom for oral sex.

It probably makes little difference whether you swallow cum or spit it out.

If you have HIV

If you have HIV:

• keep your cum out of men's mouths
• avoid being sucked if your cock has cuts or sores on it.