HIV can only be passed on when body fluids from someone with HIV get into the bloodstream of someone else.
The only body fluids that contain enough HIV to be infectious are blood, breast milk, semen, vaginal fluids and moisture from the rectum. When someone is taking HIV treatment, the amount of HIV in their body fluids is reduced, reducing infectiousness.
The main ways HIV is transmitted are:
- Through having anal or vaginal sex without a condom, or through performing oral sex on a man without a condom, although this is lower risk.
- Through blood-to-blood contact. This mainly happens through sharing drug injecting equipment. Before screening was introduced, some people were infected with blood and blood products during medical treatment. Very rarely, healthcare workers have been infected after accidentally pricking themselves with a needle contaminated with blood.
- From a mother to her baby. This is also called vertical transmission, and can happen during pregnancy, birth or breastfeeding. With the right treatment and care, the risk of HIV being passed from the mother to a baby is extremely low. This is why all pregnant women in the UK are offered an HIV test during pregnancy.
There is no risk of HIV transmission through social contact such as sharing food, using the same toilet, towels, cutlery or crockery, hugging, kissing or shaking hands.