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What Are HIV and AIDS?

  • HIV (human immunodeficiency virus) is a  that attacks the immune system.
  • AIDS (acquired immune deficiency syndrome) is a late stage of HIV infection.

There's no cure for HIV/AIDS, but medicines can help people live long, healthy lives.

What Happens In HIV Infection?

HIV attacks cells in the immune system called CD4 cells (or T cells). CD4 cells help the body fight off infections and some kinds of cancers.

What Happens In AIDS?

Over time, HIV kills more and more CD4 cells, and this leads to AIDS. In AIDS, the immune system is severely weakened. Serious infections and health problems happen.

What Are the Signs & Symptoms of HIV?

Symptoms depend on what stage of HIV infection someone has.

Acute HIV infection: This is when someone is first infected with the virus. Symptoms usually start about 2–4 weeks after infection and last a few days to a few weeks. They can include fever, headache, muscle aches, swollen glands, and a rash. Some people have very mild symptoms or don’t notice any symptoms.

Chronic HIV infection: During this next stage, a person may have no symptoms or mild symptoms. People can stay in this stage for 5–10 years, but some move to the next stage (AIDS) faster.

AIDS is the most severe stage of HIV infection. Symptoms can include:

  • very fast weight loss
  • fever
  • extreme tiredness
  • swollen glands
  • a lung infection called pneumocystis pneumonia
  • diarrhea
  • sores of the mouth, anus, and genitals
  • some types of cancers
  • skin problems

How Do People Get HIV?

HIV spreads when infected blood or body fluids (such as semen or vaginal fluids) enter the body. This can happen:

  • during sex (especially anal sex and vaginal sex)
  • through sharing needles for injecting drugs or tattooing
  • by getting stuck with a needle that has an infected person's blood on it

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

HIV does NOT spread through:

  • pee, poop, spit, throw-up, or sweat (as long as no blood is present)
  • coughing or sneezing
  • holding hands
  • sharing eating utensils or drinking glasses

How Is HIV Diagnosed?

Health care providers usually diagnose HIV through blood tests. Someone who has HIV is said to be "HIV positive."

Home tests also are available without a prescription at the drugstore.

How Is HIV Treated?

Most people with HIV can stay healthy by taking medicines called antiretrovirals. Antiretrovirals help lower the viral load (how much HIV is in the body) so that the CD4 count can go up.

The goal of treatment is for the viral load to be undetectable (this means there is too little virus to show up on blood tests). Getting to an undetectable viral load takes at least 3–6 months on medicine. Continuing to take the medicine can keep the virus at undetectable levels. If medicines are stopped, the virus levels will go up.

What Can Help Prevent HIV?

To lower their risk of getting HIV, people should:

  • Avoid sharing any kind of needle.
  • Avoid sharing razors or other personal objects that may touch blood.
  • Not touch anyone else's blood (such as from a cut or sore).
  • Use a latex condom every time they have sex (including vaginal, oral, or anal sex).

What Can Help Prevent the Spread of HIV to Others?

People who have HIV should:

  • Not share any kind of needle.
  • Not share razors or other personal objects that may touch blood.
  • Keep cuts and sores covered with a bandage.

If they're sexually active, they also should:

  • Talk to sexual partners about their HIV status (this is a law in some states) and about getting tested. To find a testing site, visit the CDC's National HIV and STD Testing Resources. Their partners can consider taking a medicine every day (called PrEP or pre-exposure prophylaxis) to lower the risk of getting infected with HIV.

Someone taking antiretrovirals whose viral load is undetectable is less likely to spread HIV to others (but it can still happen).

What Else Should I Know?

By taking medicines and getting regular medical care, HIV-positive people can live long and healthy lives.

If you have HIV or AIDS, be sure to:

  • go to all doctor visits
  • take all medicines exactly as directed
  • go for all follow-up blood tests
  • understand what HIV/AIDS is and how it spreads
  • be physically active, get enough sleep, and eat well

The medical care team is there for you. They'll help you get the best treatment, and can offer support.

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Medically reviewed by: Amy W. Anzilotti, MD
Date reviewed: April 2024