HIV Prevention

The Basics of HIV Prevention

Last Reviewed: July 10, 2026

Key Points

  • Protect yourself from HIV: Use condoms correctly every time you have sex, use pre-exposure prophylaxis (PrEP) if you believe you are likely to be exposed to HIV, and avoid sharing drug injection equipment. If you are exposed to HIV and aren't taking PrEP, consider taking post-exposure prophylaxis (PEP) within 72 hours of HIV exposure.
  • Protect others if you have HIV: Take HIV medicine (called antiretroviral therapy or ART) as prescribed by your doctor. When taken as prescribed, HIV medicines can eliminate any risk of sexual HIV transmission (see Undetectable = Untransmittable, or U=U).
  • Prevent perinatal transmission: If you have HIV, take or continue taking HIV medicines throughout pregnancy, childbirth, and breastfeeding. Consider using PrEP if you have a partner with HIV and plan on getting pregnant.

 

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.

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.

View the HIVinfo Understanding How HIV is Transmitted fact sheet and the You Can Safely Share…With Someone With HIV infographic for more information on how HIV transmission can and cannot occur.

How can I reduce the chances of getting HIV?

Anyone can get HIV, but certain actions can help reduce the likelihood of HIV transmission.

  • Get tested. Talk to your partners about testing for HIV and other sexually transmitted infections (STIs) before you have sex and on an ongoing basis. Having an untreated STI can increase the likelihood of HIV transmission. Use the GetTested locator to find a testing location near you.
  • Choose safer 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 correctly every time you have sex. Condoms help prevent the spread of STIs, including HIV. Read this fact sheet from CDC on condom use.
  • Know your sexual partners. The likelihood of coming into contact with HIV or another STI may increase when you have more sexual partners or partners you aren’t familiar with.
  • Talk to your health care provider about pre-exposure prophylaxis (PrEP). PrEP is an HIV prevention option if you do not have HIV but are at an increased risk of getting HIV (for example, if your partner has HIV or if you inject drugs). For more information, read the HIVinfo fact sheet on Pre-Exposure Prophylaxis (PrEP).
  • Do not share injection drug equipment. Because HIV is transmitted through blood, injecting drugs using shared equipment can significantly increase the odds of HIV transmission. Never share drug injection equipment with others.

If I have HIV, how can I prevent passing it to others?

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 an undetectable viral load have no risk of transmitting HIV to sexual partners, a concept known as Undetectable = Untransmittable (or U=U). People with a detectable viral load can transmit HIV, even if they are taking ART. For this reason, regular viral load testing is recommended.

Although HIV medicines can reduce the chances of HIV transmission, they do not prevent transmission of other STIs. 

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

  • Using condoms correctly every time you have sex
  • Communicating about your HIV status
  • Talking to your partners about taking PrEP
  • Attending all follow-up appointments
  • Not sharing drug injection equipment

How else are HIV medicines used for prevention?

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

  • Post-exposure prophylaxis (PEP) 
    PEP refers to taking a short course (28 days) of HIV medicines to prevent HIV transmission, starting within 72 hours after a possible exposure. PEP should not be used regularly. For more information, read the HIVinfo fact sheet on Post-Exposure Prophylaxis (PEP).
  • Prevention of perinatal transmission of HIV 
    HIV medicines are used during pregnancy, childbirth, and while breastfeeding to maintain an undetectable viral load, which significantly lowers any risk of perinatal transmission of HIV. After birth, infants receive HIV medicine to reduce the chances of transmission if exposure occurred during childbirth. For more information, read the HIVinfo fact sheet on Preventing Perinatal Transmission of HIV During Pregnancy and Childbirth.

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

From CDC:

From the HIV Clinical Practice Guidelines at Clinicalinfo.HIV.gov:

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