Acquired immunodeficiency syndrome (AIDS), is an ongoing, also called chronic, condition. It's caused by the human immunodeficiency virus, also called HIV. HIV damages the immune system so that the body is less able to fight infection and disease. If HIV isn't treated, it can take years before it weakens the immune system enough to become AIDS. Thanks to treatment, most people in the U.S. don't get AIDS.

HIV is spread through contact with genitals, such as during sex without a condom. This type of infection is called a sexually transmitted infection, also called an STI. HIV also is spread through contact with blood, such as when people share needles or syringes. It is also possible for a person with untreated HIV to spread the virus to a child during pregnancy, childbirth or breastfeeding.

There's no cure for HIV/AIDS. But medicines can control the infection and keep the disease from getting worse. Antiviral treatments for HIV have reduced AIDS deaths around the world. There's an ongoing effort to make ways to prevent and treat HIV/AIDS more available in resource-poor countries.


The symptoms of HIV and AIDS vary depending on the person and the phase of infection.

Primary infection, also called acute HIV

Some people infected by HIV get a flu-like illness within 2 to 4 weeks after the virus enters the body. This stage may last a few days to several weeks. Some people have no symptoms during this stage.

Possible symptoms include:

  • Fever.
  • Headache.
  • Muscle aches and joint pain.
  • Rash.
  • Sore throat and painful mouth sores.
  • Swollen lymph glands, also called nodes, mainly on the neck.
  • Diarrhea.
  • Weight loss.
  • Cough.
  • Night sweats.

These symptoms can be so mild that you might not notice them. However, the amount of virus in your bloodstream, called viral load, is high at this time. As a result, the infection spreads to others more easily during primary infection than during the next stage.

Clinical latent infection, also called chronic HIV

In this stage of infection, HIV is still in the body and cells of the immune system, called white blood cells. But during this time, many people don't have symptoms or the infections that HIV can cause.

This stage can last for many years for people who aren't getting antiretroviral therapy, also called ART. Some people get more-severe disease much sooner.

Symptomatic HIV infection

As the virus continues to multiply and destroy immune cells, you may get mild infections or long-term symptoms such as:

  • Fever.
  • Fatigue.
  • Swollen lymph glands, which are often one of the first symptoms of HIV infection.
  • Diarrhea.
  • Weight loss.
  • Oral yeast infection, also called thrush.
  • Shingles, also called herpes zoster.
  • Pneumonia.

Progression to AIDS

Better antiviral treatments have greatly decreased deaths from AIDS worldwide. Thanks to these lifesaving treatments, most people with HIV in the U.S. today don't get AIDS. Untreated, HIV most often turns into AIDS in about 8 to 10 years.

Having AIDS means your immune system is very damaged. People with AIDS are more likely to develop diseases they wouldn't get if they had healthy immune systems. These are called opportunistic infections or opportunistic cancers. Some people get opportunistic infections during the acute stage of the disease.

The symptoms of some of these infections may include:

  • Sweats.
  • Chills.
  • Fever that keeps coming back.
  • Ongoing diarrhea.
  • Swollen lymph glands.
  • Constant white spots or lesions on the tongue or in the mouth.
  • Constant fatigue.
  • Weakness.
  • Rapid weight loss.
  • Skin rashes or bumps.

When to see a doctor

If you think you may have been infected with HIV or are at risk of contracting the virus, see a healthcare professional as soon as you can.

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HIV is caused by a virus. It can spread through sexual contact, shooting of illicit drugs or use of shared needles, and contact with infected blood. It also can spread from parent to child during pregnancy, childbirth or breastfeeding.

HIV destroys white blood cells called CD4 T cells. These cells play a large role in helping the body fight disease. The fewer CD4 T cells you have, the weaker your immune system becomes.

How does HIV become AIDS?

You can have an HIV infection with few or no symptoms for years before it turns into AIDS. AIDS is diagnosed when the CD4 T cell count falls below 200 or you have a complication you get only if you have AIDS, such as a serious infection or cancer.

How HIV spreads

You can get infected with HIV if infected blood, semen or fluids from a vagina enter your body. This can happen when you:

  • Have sex. You may become infected if you have vaginal or anal sex with an infected partner. Oral sex carries less risk. The virus can enter your body through mouth sores or small tears that can happen in the rectum or vagina during sex.
  • Share needles to inject illicit drugs. Sharing needles and syringes that have been infected puts you at high risk of HIV and other infectious diseases, such as hepatitis.
  • Have a blood transfusion. Sometimes the virus may be transmitted through blood from a donor. Hospitals and blood banks screen the blood supply for HIV. So this risk is small in places where these precautions are taken. The risk may be higher in resource-poor countries that are not able to screen all donated blood.
  • Have a pregnancy, give birth or breastfeed. Pregnant people who have HIV can pass the virus to their babies. People who are HIV positive and get treatment for the infection during pregnancy can greatly lower the risk to their babies.

How HIV doesn't spread

You can't become infected with HIV through casual contact. That means you can't catch HIV or get AIDS by hugging, kissing, dancing or shaking hands with someone who has the infection.

HIV isn't spread through air, water or insect bites. You can't get HIV by donating blood.

Risk factors

Anyone of any age, race, sex or sexual orientation can have HIV/AIDS. However, you're at greatest risk of HIV/AIDS if you:

  • Have unprotected sex. Use a new latex or polyurethane condom every time you have sex. Anal sex is riskier than is vaginal sex. Your risk of HIV increases if you have more than one sexual partner.
  • Have an STI. Many STIs cause open sores on the genitals. These sores allow HIV to enter the body.
  • Inject illicit drugs. If you share needles and syringes, you can be exposed to infected blood.


HIV infection weakens your immune system. The infection makes you much more likely to get many infections and certain types of cancers.

Infections common to HIV/AIDS

  • Pneumocystis pneumonia, also called PCP. This fungal infection can cause severe illness. It doesn't happen as often in the U.S. because of treatments for HIV/AIDS. But PCP is still the most common cause of pneumonia in people infected with HIV.
  • Candidiasis, also called thrush. Candidiasis is a common HIV-related infection. It causes a thick, white coating on the mouth, tongue, esophagus or vagina.
  • Tuberculosis, also called TB. TB is a common opportunistic infection linked to HIV. Worldwide, TB is a leading cause of death among people with AIDS. It's less common in the U.S. thanks to the wide use of HIV medicines.
  • Cytomegalovirus. This common herpes virus is passed in body fluids such as saliva, blood, urine, semen and breast milk. A healthy immune system makes the virus inactive, but it stays in the body. If the immune system weakens, the virus becomes active, causing damage to the eyes, digestive system, lungs or other organs.
  • Cryptococcal meningitis. Meningitis is swelling and irritation, called inflammation, of the membranes and fluid around the brain and spinal cord, called meninges. Cryptococcal meningitis is a common central nervous system infection linked to HIV. A fungus found in soil causes it.
  • Toxoplasmosis. This infection is caused by Toxoplasma gondii, a parasite spread primarily by cats. Infected cats pass the parasites in their stools. The parasites then can spread to other animals and humans.

    Toxoplasmosis can cause heart disease. Seizures happen when it spreads to the brain. And it can be fatal.

Cancers common to HIV/AIDS

  • Lymphoma. This cancer starts in the white blood cells. The most common early sign is painless swelling of the lymph nodes most often in the neck, armpit or groin.
  • Kaposi sarcoma. This is a tumor of the blood vessel walls. Kaposi sarcoma most often appears as pink, red or purple sores called lesions on the skin and in the mouth in people with white skin. In people with Black or brown skin, the lesions may look dark brown or black. Kaposi sarcoma also can affect the internal organs, including the lungs and organs in the digestive system.
  • Human papillomavirus (HPV)-related cancers. These are cancers caused by HPV infection. They include anal, oral and cervical cancers.

Other complications

  • Wasting syndrome. Untreated HIV/AIDS can cause a great deal of weight loss. Diarrhea, weakness and fever often happen with the weight loss.
  • Brain and nervous system, called neurological, complications. HIV can cause neurological symptoms such as confusion, forgetfulness, depression, anxiety and difficulty walking. HIV-associated neurological conditions can range from mild symptoms of behavior changes and reduced mental functioning to severe dementia causing weakness and not being able to function.
  • Kidney disease. HIV-associated nephropathy (HIVAN) is swelling and irritation, called inflammation, of the tiny filters in the kidneys. These filters remove excess fluid and waste from the blood and pass them to the urine. Kidney disease most often affects Black and Hispanic people.
  • Liver disease. Liver disease also is a major complication, mainly in people who also have hepatitis B or hepatitis C.


There's no vaccine to prevent HIV infection and no cure for HIV/AIDS. But you can protect yourself and others from infection.

To help prevent the spread of HIV:

  • Consider preexposure prophylaxis, also called PrEP. There are two PrEP medicines taken by mouth, also called oral, and one PrEP medicine given in the form of a shot, called injectable. The oral medicines are emtricitabine-tenofovir disoproxil fumarate (Truvada) and emtricitabine-tenofovir alafenamide fumarate (Descovy). The injectable medicine is called cabotegravir (Apretude). PrEP can reduce the risk of sexually transmitted HIV infection in people at very high risk.

    PrEP can reduce the risk of getting HIV from sex by about 99% and from injecting drugs by at least 74%, according to the Centers for Disease Control and Prevention. Descovy hasn't been studied in people who have sex by having a penis put into their vaginas, called receptive vaginal sex.

    Cabotegravir (Apretude) is the first U.S. Food and Drug Administration-approved PrEP that can be given as a shot to reduce the risk of sexually transmitted HIV infection in people at very high risk. A healthcare professional gives the shot. After two once-monthly shots, Apretude is given every two months. The shot is an option in place of a daily PrEP pill.

    Your healthcare professional prescribes these medicines to prevent HIV only to people who don't already have HIV infection. You need an HIV test before you start taking any PrEP. You need to take the test every three months for the pills or before each shot for as long as you take PrEP.

    You need to take the pills every day or closely follow the shot schedule. You still need to practice safe sex to protect against other STIs. If you have hepatitis B, you should see an infectious disease or liver specialist before beginning PrEP therapy.

  • Use treatment as prevention, also called TasP. If you have HIV, taking HIV medicines can keep your partner from getting infected with the virus. If your blood tests show no virus, that means your viral load can't be detected. Then you won't transmit the virus to anyone else through sex.

    If you use TasP, you must take your medicines exactly as prescribed and get regular checkups.

  • Use post-exposure prophylaxis, also called PEP, if you've been exposed to HIV. If you think you've been exposed through sex, through needles or in the workplace, contact your healthcare professional or go to an emergency room. Taking PEP as soon as you can within the first 72 hours can greatly reduce your risk of getting HIV. You need to take the medicine for 28 days.
  • Use a new condom every time you have anal or vaginal sex. Both male and female condoms are available. If you use a lubricant, make sure it's water based. Oil-based lubricants can weaken condoms and cause them to break.

    During oral sex, use a cut-open condom or a piece of medical-grade latex called a dental dam without a lubricant.

  • Tell your sexual partners you have HIV. It's important to tell all your current and past sexual partners that you're HIV positive. They need to be tested.
  • Use clean needles. If you use needles to inject illicit drugs, make sure the needles are sterile. Don't share them. Use needle-exchange programs in your community. Seek help for your drug use.
  • If you're pregnant, get medical care right away. You can pass HIV to your baby. But if you get treatment during pregnancy, you can lessen your baby's risk greatly.
  • Consider male circumcision. Studies show that removing the foreskin from the penis, called circumcision, can help reduce the risk of getting HIV infection.

Feb. 09, 2024
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