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What Are HIV and AIDS?

HIV (human immunodeficiency virus) is a virus that attacks the immune system, the body’s defense against infections.

AIDS (acquired immune deficiency syndrome) can happen after someone has had HIV for many years and isn’t treated. If HIV becomes AIDS, the immune system can’t fight germs well. So people with AIDS often get serious infections and health problems. But not all people with HIV will develop AIDS.

How Does HIV Spread?

HIV spreads when blood, semen ("cum"), or vaginal fluids that have HIV enter the body. Because symptoms can be mild at first, people with HIV might not know they have it and could possibly spread it to other people.

Someone could get HIV:

  • during sex (especially anal and vaginal sex)
  • through sharing needles for injecting drugs or tattooing
  • by getting stuck with a needle that has blood with HIV

HIV also can pass from mother to child during pregnancy, childbirth, or breastfeeding.

HIV does not spread through:

  • pee, poop, spit, vomit, or sweat (as long as there isn’t any blood)
  • sharing drinking glasses or eating utensils (like forks, spoons, knives, or chopsticks)
  • coughing or sneezing
  • holding hands, hugging, or kissing

How Can I Protect Myself From HIV?

The best way to protect yourself from HIV is to not share needles and not have sex. This includes vaginal, anal, or oral sex; sex using fingers; or other sexual contact.

If you decide to have sex, you can reduce your risk of getting HIV by:

  • Using protection like a condom, finger condom, or dental dam each time you have sex.
  • Having just one sexual partner.
  • Getting tested for HIV and making sure your partner does too.
  • Being tested and treated for sexually transmitted diseases (STDs) (also called sexually transmitted infections or STIs). Having an STD increases a person's chances of getting HIV. For example, some STDs cause sores through which HIV could enter the body.
  • Taking a kind of medicine called PrEP (pre-exposure prophylaxis). PrEP helps prevent HIV from spreading when condoms break, aren’t used, or aren’t used the whole time during sex. But PrEP doesn’t protect against other STDs.

What Else Should I Know?

Medicines can help people with HIV stay healthy. They can also prevent HIV from becoming AIDS.

Knowing about AIDS and how HIV spreads can help you make safer choices about sex. Talk with your doctor if you have any questions about AIDS and HIV, or want to get tested.

Medically reviewed by: Joy Friedman, MD
Date reviewed: June 2024