HIV Prevention

The Basics of HIV Prevention

Last Reviewed: August 9, 2021

Key Points

  • People can get or transmit HIV only through specific activities, such as sex or injection drug use. HIV can be transmitted only in certain body fluids from a person who has HIV. These fluids are blood, semen, pre-seminal fluids, rectal fluids, vaginal fluids, and breast milk.
  • To reduce your risk of HIV, use condoms correctly every time you have sex. Do not inject drugs. If you do, use only sterile injection equipment and water, and never share your equipment with others.
  • If you do not have HIV but are at risk of getting HIV, talk to your health care provider about pre-exposure prophylaxis (PrEP). PrEP involves taking a specific HIV medicine every day to reduce the risk of getting HIV through sex or injection drug use.

How is HIV transmitted?

The person-to-person spread of HIV is called HIV transmission. People can get or transmit HIV only through specific activities, such as sex or injection drug use. HIV can be transmitted only in certain body fluids from a person who has HIV:

  • Blood
  • Semen
  • Pre-seminal fluids
  • Rectal fluids
  • Vaginal fluids
  • Breast milk

HIV transmission is only possible if these fluids come in contact with a mucous membrane or damaged tissue or are directly injected into the bloodstream (from a needle or syringe). Mucous membranes are found inside the rectum, the vagina, the opening of the penis, and the mouth.

In the United States, HIV is spread mainly by:

  • Having anal or vaginal sex with someone who has HIV without using a condom or taking medicines to prevent or treat HIV
  • Sharing injection drug equipment (works), such as needles, with someone who has HIV

HIV can also spread from a woman with HIV to her child during pregnancy, childbirth (also called labor and delivery), or breastfeeding. This is called perinatal transmission of HIV. Perinatal transmission of HIV is also called mother-to-child transmission of HIV.

You cannot get HIV from casual contact with a person who has HIV, such as a handshake, a hug, or a closed-mouth kiss. And you cannot get HIV from contact with objects, such as toilet seats, doorknobs, or dishes used by a person who has HIV.

Use the You Can Safely Share…With Someone With HIV infographic from HIVinfo to spread this message.

How can a person reduce the risk of getting HIV?

Anyone can get HIV, but you can take steps to protect yourself from HIV.

  • Get tested for HIV. Talk to your partner about HIV testing and get tested before you have sex. Use the GetTested locator from the Centers for Disease Control and Prevention (CDC) to find an HIV testing location near you.
  • Choose less risky sexual behaviors. HIV is mainly spread by having anal or vaginal sex without a condom or without taking medicines to prevent or treat HIV.
  • Use condoms every time you have sex. Read this fact sheet from CDC on how to use condoms correctly.
  • Limit your number of sexual partners. The more partners you have, the more likely you are to have a partner with poorly controlled HIV or to have a partner with a sexually transmitted disease (STD). Both of these factors can increase the risk of HIV.
  • Get tested and treated for STDs. Insist that your partners get tested and treated, too. Having an STD can increase your risk of getting HIV or spreading it to others.
  • Talk to your health care provider about pre-exposure prophylaxis (PrEP). PrEP is an HIV prevention option for people who do not have HIV but who are at risk of getting HIV. PrEP involves taking a specific HIV medicine every day to reduce the risk of getting HIV through sex or injection drug use. For more information, read the HIVinfo fact sheet on Pre-Exposure Prophylaxis (PrEP).
  • Do not inject drugs. But if you do, use only sterile drug injection equipment and water, and never share your equipment with others.

How can a person who is HIV positive prevent passing HIV to others?

Take HIV medicines daily. Treatment with HIV medicines (called antiretroviral therapy or ART) helps people with HIV live longer, healthier lives. ART cannot cure HIV, but it can reduce the amount of HIV in the body (called the viral load). One of the main goals of ART is to reduce a person's viral load to an undetectable level. An undetectable viral load means that the level of HIV in the blood is too low to be detected by a viral load test. People with HIV who maintain an undetectable viral load have effectively no risk of transmitting HIV to an HIV-negative partner through sex.

Here are some other steps you can take to prevent HIV transmission:

  • Use condoms correctly every time you have sex.
  • Talk to your partner about taking PrEP.
  • If you inject drugs, do not share your needles, syringes, or other drug equipment with your partner.

Are HIV medicines used at other times to prevent HIV transmission?

Yes, HIV medicines are also used for post-exposure prophylaxis (PEP) and to prevent perinatal transmission of HIV.

  • Post-exposure prophylaxis (PEP)
    PEP means taking HIV medicines within 72 hours after a possible exposure to HIV to prevent HIV infection. PEP should be used only in emergency situations. It is not meant for regular use by people who may be exposed to HIV frequently. For more information, read the HIVinfo fact sheet on Post-Exposure Prophylaxis (PEP).
  • Prevention of perinatal transmission of HIV
    Pregnant women with HIV take HIV medicines for their own health and to prevent perinatal transmission of HIV. After birth, babies born to women with HIV receive HIV medicine to protect them from infection with any HIV that may have passed from mother to child during childbirth. For more information, read the HIVinfo fact sheet on Preventing Perinatal Transmission of HIV.

This fact sheet is based on information from the following sources:

From CDC:

From the Department of Health and Human Services:

Also see the HIV Source collection of HIV links and resources.