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HIV attacks cells in the immune system, gradually reducing the body's ability to fight infections and disease. When immune system damage from HIV has reached a certain severity, the person is said to have AIDS. This damage may be measured by counting certain types of immune system cells or by identifying a disease that commonly develops in people with AIDS but rarely affects healthy people.

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2. How do people get HIV/AIDS?

HIV is passed from one person to another in blood, semen, vaginal fluid or breast milk.

According to the Centers for Disease Control and Prevention (CDC), HIV may spread through:

Sex, including anal or oral sex, with an infected person.
Sharing injection drug needles with an infected person.
Transmission to a child from an infected mother. This can happen when a baby is in the womb, during birth if the baby is exposed to the mother's blood, or after birth through infected breast milk.

HIV can also spread through transfusions with infected blood or plasma. This is extremely rare, however, as all donated blood in the United States is tested for HIV.

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3. Where does HIV come from?

In 1999, researchers discovered the origin of HIV in a species of chimpanzee in west Africa. They believe that these primates are the original source of the virus, and that it passed to humans when hunters were exposed to infected blood.

HIV has been in the United States since at least the late 1970s.

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4. How can I tell if I'm infected with HIV?

HIV often causes no symptoms for several years after infection. So an HIV test is the only way to know if you're infected.

When HIV does cause symptoms, they can include:

Rapid weight loss.
Recurring fever or night sweats.
Feeling very tired without a known reason.
Swollen lymph glands in the armpits, groin or neck.
Diarrhea that lasts more than a week.
Sores.
Pneumonia.
Red, brown, pink or purplish blotches on or under the skin, or inside the mouth, nose or eyelids.
Memory loss, depression and other neurological disorders.

These symptoms can have causes other than HIV. If you're at all concerned that you may have HIV, you should get tested.

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5. How long does it take for HIV to cause AIDS?

Researchers once estimated that about half of people with HIV would develop AIDS within 10 years. But advances in HIV treatment have changed this prediction. Treatment cannot kill the virus, but it can slow its effects on the immune system for many years.

Early treatment offers the best opportunity for delaying the progression from HIV to AIDS as long as possible.

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6. How is HIV/AIDS treated?

Many combinations of medicines can be used to slow or stop the spread of HIV within the body. This slows the destruction of the immune system, delaying the onset or progression of AIDS.

Many factors are considered in deciding when to start treatment for HIV infection. CDC recommends seeing a doctor who has experience treating HIV/AIDS.

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7. What are the risk factors for HIV infection?

According to CDC, people are more likely to be infected with HIV if they:

Have ever shared injection drug needles, syringes or other equipment.
Have ever had sex without a condom with someone who had HIV.
Have ever had a sexually transmitted disease, such as chlamydia or gonorrhea.
Have ever had sex with someone who has done any of these things.

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8. Where can I get tested for HIV?

HIV testing is offered at doctors' offices, health departments, clinics and other locations throughout the country. Home testing kits are also sold at some pharmacies. You can find a test site near you at CDC's national testing resources website, gettested.cdc.gov.

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9. Who should be tested?

Everybody between ages 13 and 64 should be tested for HIV at least once, according to CDC. If you've done anything since your last test that could have exposed you to the virus, ask your doctor whether you should be tested again.

It generally takes 23 days to 3 months for the body to start making HIV antibodies, proteins produced by the immune system that HIV tests look for.

If you think you're infected but haven't been tested, remember that HIV infection can be passed to others even in its earliest stages. And if you do have HIV, getting any other type of infection could be especially dangerous for you. It's also possible that you could get infected with more than one form of HIV, which makes treatment especially challenging. For these reasons it's vital that you protect yourself and others from further possible exposure to HIV.

CDC also recommends that all pregnant women be tested for HIV because of the risk of passing the virus on to the baby.

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10. What if I test positive?

If you have HIV, it's best that you start protecting your health immediately. Treatment can help you stay well and may delay the onset of AIDS.

You should take these steps right away:

See a doctor, even if you don't feel sick. It's never too early to start thinking about treatment options.
Get a tuberculosis (TB) test. People with HIV are at increased risk for TB and can be infected without knowing it. TB is serious but can be treated if caught early.
Don't smoke, use illegal drugs, abuse alcohol or do other things that can weaken your immune system.

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11. How can I reduce my risk of HIV?

To reduce your risk of HIV, avoid sharing shaving razors, toothbrushes, needles or syringes. If you have sex, only have sex with one person who only has sex with you, and whom you know to be uninfected.

Use a condom correctly and consistently every time you have sex if you aren't certain that your partner doesn't have HIV.

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12. Where can I go for more information?

To get more information about HIV, visit the HIV/AIDS health topic center. You can also find out more at these websites:

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Reviewed 6/21/2023