What HIV needs to spread

HIV can only pass from one person to another in certain body fluids: blood, semen and pre-seminal fluid, rectal fluid, vaginal fluid and breast milk. For an infection to happen, one of those fluids from a person with HIV has to get into the body. It can enter through a mucous membrane (the thin lining inside the vagina, rectum, penis or mouth), through damaged tissue, or by injection straight into the bloodstream.

CDC puts it simply: you can’t get or pass on HIV through activities that don’t involve contact with these body fluids. HIV also doesn’t survive long outside the body and can’t reproduce outside a human host.

That rules out almost everything in daily life.

Things that carry no risk

You cannot get HIV from:

  • Hugging, shaking hands or touching. Unbroken skin is a strong barrier. Even blood on intact skin doesn’t let HIV in.
  • Closed-mouth kissing. CDC states you can’t transmit HIV this way.
  • Saliva, sweat or tears. HIV is not transmitted through saliva, and sweat and tears don’t carry it either.
  • Sharing food, drinks, cups or cutlery.
  • Toilet seats, towels, bedding or door handles.
  • Mosquitoes, ticks or other insects. Insects don’t carry HIV from one person to another.
  • Coughing, sneezing or breathing the same air. HIV doesn’t spread through air or water.
  • Living with, working with or caring for someone with HIV in everyday ways.

Myths that worry people

“What if I touched a little blood?” If your skin wasn’t broken, there is no risk. If blood got into a fresh cut, your eyes or your mouth, that is a different situation. See blood in your eyes, mouth or a cut.

“Can you get HIV from being bitten or spat on?” CDC rates the risk from biting and spitting as negligible, and says there is no chance of HIV from spitting. A bite could only matter in rare cases where it breaks the skin and blood is involved. More on kissing, biting and spitting.

“What about a needle on the street?” A discarded needle is not the same as everyday contact. The real chance of infection is small, but it’s worth getting advice the same day. See needlestick injuries.

“Can HIV live on a seat or a towel?” HIV doesn’t survive long on surfaces, and touching a surface doesn’t put anything into your bloodstream. Read more about how long HIV survives outside the body.

What does carry risk

For comparison, the exposures that can pass HIV on involve sex or blood. If a partner has HIV and isn’t on effective treatment, CDC estimates the risk of one act of receptive anal sex at 1.4% (about 1 in 72), and of sharing a needle at 0.63% (about 1 in 160). Oral sex is much lower: CDC rates it as low, and the calculator uses about 0.01% (about 1 in 10,000).

The risk from sex can drop to zero. A person with HIV who keeps an undetectable viral load on treatment doesn’t pass HIV on through sex (U=U). PrEP (pre-exposure prophylaxis), condoms and PEP (post-exposure prophylaxis) all lower the risk too. The understanding HIV risk guide explains how the numbers fit together.

What to do now

If what happened to you is on the no-risk list above, you don’t need PEP and you don’t need a test because of it. It’s normal to keep worrying after a scare, and if the worry won’t settle, HIV anxiety has practical ways to cope.

If something else happened as well, such as sex without a condom or a cut from a used needle, look at that exposure on its own. If it was in the last 72 hours, ask about PEP today; it works best when started within 24 hours. How to get PEP

CDC recommends that everyone aged 13 to 64 gets tested for HIV at least once. A routine test is a simple way to put your mind at rest. See the HIV testing guide.