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Cancer Risk and Prevention

What Are HIV and AIDS?

Human immunodeficiency virus (HIV) attacks and destroys the body’s immune system by killing a specific type of white blood cell known as the CD4 cell (or helper T-cell).

Acquired immune deficiency syndrome (AIDS) is the most advanced stage of HIV. AIDS happens when HIV has badly damaged the immune system, a process that may take years. The loss of CD4 cells leads to a weakened immune system, which allows infections and cancers to occur that usually don’t affect healthy people. These are called opportunistic infections and opportunistic cancers.  

As treatment with anti-retroviral therapy (ART) has become available, fewer people living with HIV (PLWH) are developing AIDS. In fact, PLWH can live long and healthy lives by taking ART. 

How are people infected with HIV?

 HIV can spread when an uninfected person is exposed to blood or certain body fluids (semen, vaginal secretions, or breast milk) from an infected person. There are several possible routes of HIV transmission (spread):

  • Unprotected vaginal or anal sex with an HIV-infected person
  • Sharing needles or supplies used to prepare drugs with an HIV-infected person
  • Exposure of infants whose mothers are infected with HIV before, during, and right after birth
  • Breastfeeding by mothers with HIV
  • Injuries or accidents which break the skin (usually needle sticks) in health care workers while handling the blood of or caring for people infected with HIV

HIV is NOT spread:

  • Through casual contact like talking, shaking hands, hugging, coughing, or sneezing
  • Through saliva (spit), tears, or sweat
  • By sharing dishes, bathrooms, telephones, or computers
  • By insect or tick bites or through water

With new precautions and careful testing at blood banks, the risk of HIV spread through transfusions of blood and blood products has been almost eliminated. There is a 1 in 2 million chance of being infected with HIV through a blood transfusion in the United States.

Infection through organ transplants from HIV-infected donors is very rare, because donor organs and tissues are thoroughly tested for HIV before transplant.

How can the risk of HIV spread be reduced?

  • Using condoms during vaginal or anal sex: Avoid unprotected sex with someone living with HIV. If one partner is known to be infected or their HIV status is uncertain, using condoms every time, from start to finish, can lower the risk.
  • Having injection drug users use clean, sterile needles and supplies: Never share needles. The second most common cause of HIV infection is sharing used needles or drug equipment with injection drug users living with HIV.
  • Using pre-exposure prophylaxis (PrEP):  For people who are at high risk of HIV infection, taking medicine (as a pill every day) is another way to help lower the risk of infection.
  • Taking post-exposure prophylaxis (PEP): If you have been exposed to HIV, such as from a broken condom or needle stick injury, PEP treatment might reduce the risk of HIV infection. This treatment involves taking anti-HIV drugs every day for 4 weeks. PEP works best if started as soon as possible after exposure, within 72 hours.
  • Treatment as prevention: ART greatly reduces the amount of virus in the body, with the goal of being undetectable. Undetectable HIV viral load means HIV is not transmittable and cannot be passed on to others.
  • Reducing mother-to-infant transmission: All pregnant women should be tested for HIV. If HIV is diagnosed, treatment with ART should be started right away. Treating the mothers and infants with anti-HIV drugs and avoiding breastfeeding reduces the risk of HIV infection in infants. Also, the baby may need to be delivered by C-section if the mother’s HIV levels are high.

Should I be tested for HIV?

HIV infection may not cause symptoms for years, and a person can have HIV for a long time and not know it. The US Centers for Disease Control and Prevention (CDC) recommends HIV testing at least once for everyone between the ages of 13 and 64. However, HIV testing is often not done unless you have certain medical problems, are pregnant, or ask to be tested.

If you have any doubt about your HIV status, talk with your doctor or visit a health department clinic where testing is offered. To have the HIV test done without giving your name and address (anonymous testing), you can buy a home collection kit at the drugstore or online or go to an anonymous testing site. Some state health departments also offer anonymous HIV tests.

HIV testing is covered by insurance without a co-pay. If you don’t have insurance, look for a testing site that provides free tests.

 HIV is often diagnosed after the development of opportunistic infections or cancer. But with testing, HIV infection can be diagnosed and treatment can be started before a person gets seriously ill.

How is HIV treated?

HIV is a type of virus called a retrovirus. Treatment for HIV is known as anti-retroviral therapy or ART. Treatment for HIV often uses 3 or more ART drugs.  These medications are taken daily to help keep the virus from making more copies of itself (reproducing).  

The combination of anti-HIV drugs varies with each person depending on:

  • Disease stage
  • Whether the infection is resistant to any of the ART medicines
  • Side effects
  • Other factors, such as other diseases that person may have

Different combinations might be tried. Over time the ART medications may need to be changed.

Once a person has been diagnosed with HIV, ART should start as soon as possible. HIV infections cannot be cured, but they can be managed long term with ART. By taking ART regularly, PLWH can have a normal life span and people with AIDS can live longer. 

The main goal of ART is to lower the amount of HIV in a person’s blood. This can reduce damage to the immune system and decrease the risk of opportunistic infections, cancers, and AIDS. Reducing the amount of HIV also greatly lowers the risk of spread.

It is important that a PLWH takes their ART as prescribed to keep their HIV blood levels as low as possible. This improves a person’s quality of life and lowers the chances of serious illnesses and long-term effects of HIV.

Other measures that can be taken to support the immune system involve good self-care, such as:

  • Eating well and getting regular exercise
  • Managing stress
  • Avoiding infections (which may include staying away from people who are sick, practicing food safety, getting certain vaccines, taking antibiotics, using safer sex practices, and other measures)
  • Stopping tobacco, alcohol, and other drug use

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

National Institutes of Health. Understanding HIV. Accessed at on October 21, 2021.

Panel on Treatment of HIV During Pregnancy and Prevention of Perinatal Transmission. Recommendations for Use of Antiretroviral Drugs in Transmission in the United States. Available at LINK. Accessed at on March 25, 2022.

Steele WR, Dodd RY, Notari EP, et al. HIV, HCV, and HBV incidence and residual risk in US blood donors before and after implementation of the 12-month deferral policy for men who have sex with men. Transfusion. 2021;61(3):839-850. 

US Department of Health and Human Services. HIV Basics. Accessed at  on March 22, 2022.  

Last Revised: March 28, 2022

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