HIV Prevention

The Basics of HIV Prevention

Last Reviewed: December 11, 2023

Key Points

  • Protect yourself during sex: To reduce your risk of getting HIV, use condoms correctly every time you have sex.
  • Protect yourself if you inject drugs: Do not inject drugs. If you do, use only sterile injection equipment and water, and never share your equipment with others.
  • Protect yourself by taking PrEP: 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 or an injectable HIV medicine every two months to reduce the risk of getting HIV through sex or injection drug use.
  • Protect others if you have HIV: Take HIV medicine (called antiretroviral therapy or ART) as prescribed by your doctor. ART can reduce the amount of HIV in the blood (called viral load) to the point where a test cannot detect it (called an undetectable viral load). If you have an undetectable viral load, you will not transmit HIV to your partner through sex.
  • Prevent perinatal transmission: If you have HIV and take HIV medicine as prescribed by your doctor throughout pregnancy and childbirth, the chances of transmitting HIV to your baby are less than 1%. If you have a partner with HIV and are considering getting pregnant, talk to your doctor about PrEP to help protect you and your baby from getting HIV while you try to get pregnant, during pregnancy, or while breastfeeding.

How is HIV transmitted?

The person-to-person spread of human immunodeficiency virus (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. Bodily fluids that can transmit HIV include blood, semen (“cum”), pre-seminal fluids (“pre-cum”), rectal fluids, vaginal fluids, and breast milk.

HIV transmission is only possible if these fluids come in contact with a mucous membrane, open cuts or sores, or are directly injected into the bloodstream (from a contaminated 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 transmitted mainly by:

  • Having anal or vaginal sex with someone who has HIV without using a condom or who is not taking medicines to prevent or treat HIV.
  • Sharing injection drug equipment (“works”), such as needles or syringes, with someone who has HIV.

HIV can also be transmitted from a birthing parent with HIV to their 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.

How is HIV not transmitted?

You cannot get HIV from:

  • Casual contact with a person who has HIV, such as a handshake, a hug, or a closed-mouth kiss (“social” kissing).
  • Contact with objects, such as toilet seats, doorknobs, or dishes used by a person who has HIV.
  • Mosquitoes, ticks, or other biting insects.
  • Other sexual activities that do not involve the exchange of body fluids (for example, touching).
  • Donating blood or receiving a blood transfusion.

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

How can I 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 transmitted 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 infection (STI). Both factors can increase the risk of HIV transmission.
  • 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 transmitting 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 (for example, if your partner has HIV or if you inject drugs). PrEP involves taking a specific HIV medicine to reduce the risk of getting HIV through sex or injection drug use. PrEP medications can be given in the form of pills (taken daily) or injections (every other month). It is important to take PrEP as directed by your doctor to effectively protect you against HIV. 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 I prevent passing HIV to others if I have HIV?

Take HIV medicines as directed by your doctor. Treatment with HIV medicines (called antiretroviral therapy or ART) helps people with HIV live long, healthy 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 by taking ART consistently as prescribed have effectively no risk of transmitting HIV to an HIV-negative partner through sex.

Remember, taking HIV medicines does not prevent transmission of other STIs.

In addition to maintaining an undetectable viral load, here are some other steps you can take to make sure you prevent HIV transmission to others:

  • 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 other people.

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 people with HIV take HIV medicines for their own health and to prevent perinatal transmission of HIV (HIV can be passed from a person with HIV to their child during pregnancy, childbirth, or breastfeeding). After birth, babies born to people 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 NIH Office of AIDS Research:

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