What is Pre-Exposure Prophylaxis (PrEP)?
“PrEP” stands for Pre-Exposure Prophylaxis. PrEP is a way for people who don’t have HIV but who are at very high risk of getting it to prevent HIV infection by taking a pill every day. The pill contains two medicines that are also used to treat HIV. If you take PrEP and are exposed to HIV through sex or injection drug use, these medicines can work to keep the virus from taking hold in your body.
PrEP is a powerful HIV prevention tool and can be combined with condoms and other prevention methods to provide even greater protection than when used alone. But people who use PrEP must commit to taking the drug every day and seeing their health care provider for follow-up every 3 months.
Can Anyone Use PrEP?
PrEP is not for everyone. Federal guidelines recommend that PrEP be considered for people who are HIV-negative and at very high risk for HIV infection. This includes anyone who is in an ongoing relationship with an HIV-positive partner. It also includes anyone who:
- Is not in a mutually monogamous* relationship with a partner who recently tested HIV-negative, and
- Is a:
- gay or bisexual man who has had anal sex without a condom or been diagnosed with a sexually transmitted infection within the past 6 months;
- man who has sex with both men and women; or
- heterosexual man or woman who does not regularly use condoms during sex with partners of unknown HIV status who are at substantial risk of HIV infection (e.g., people who inject drugs or women who have bisexual male partners).
*Mutually monogamous means that you and your partner only have sex with each other and do not have sex outside the relationship.
PrEP is also recommended for people who have injected drugs in the past 6 months and have shared needles or works or been in drug treatment in the past 6 months.
If you have a partner who is HIV-positive and are considering getting pregnant, talk to your doctor about PrEP. It may be an option to protect you and your baby.
PrEP involves taking medication daily and regular visits to a health care provider.
Also, PrEP is only for people who are at ongoing substantial risk of HIV infection. For people who need to prevent HIV after a single high-risk event of potential HIV exposure—such as sex without a condom, needle-sharing injection drug use, or sexual assault—there is another option called post-exposure prophylaxis, or PEP. PEP must begin within 72 hours of exposure. See our PEP page more information.
It’s also important to remember that taking PrEP will not prevent you from getting syphilis, gonorrhea, chlamydia, or other sexually transmitted diseases. Similarly, for those taking PrEP because of injection drug use risks, PrEP will not protect you from getting hepatitis C, skin, or heart infections.
How Well Does PrEP Work?
When taken every day, PrEP has been shown to reduce the risk of HIV infection in people who are at high risk by more than 90%. PrEP is much less effective if it is not taken consistently. PrEP can be even more effective if it is combined with other ways to prevent new HIV infections like condom use, drug abuse treatment, and treatment for people living with HIV to reduce the chance of passing the virus to others.
PrEP was tested in several large studies with men who have sex with men, men who have sex with women, women who have sex with men, and people who inject drugs. Information on the details of these studies can be found at www.cdc.gov/hiv/prep.
Is PrEP Safe?
Some people in clinical studies of PrEP had early side effects such as an upset stomach or loss of appetite, but these were mild and usually went away within the first month. Some people also had a mild headache. No serious side effects were observed. If you are on PrEP, you should tell your healthcare provider if these or other symptoms become severe or do not go away.
Guidelines on PrEP Use
In May 2014, the U.S. Public Health Service and the CDC issued clinical practice guidelines for the use of PrEP in the U.S., along with a clinical providers’ supplement. These resources advise healthcare providers on determining when PrEP is right for various patients.
Information on the key points in the PrEP Guidelines can be found at http://www.cdc.gov/hiv/prep.
Where Can I Get PrEP?
If you think you may be at high risk for HIV, talk to your healthcare provider about whether PrEP is right for you.
Please see CDC’s brochure Talk to Your Doctor About PrEP for questions that you should ask your healthcare provider when discussing if PrEP is right for you.
What Medications are Used in PrEP?
The pill approved by the U.S. Food and Drug Administration (FDA) for daily use as PrEP for people at very high risk of getting HIV infection is called Truvada®. Truvada® is a combination of two HIV medications (tenofovir and emtricitabine). These medicines work by blocking important pathways that HIV uses to set up an infection. If you take PrEP daily, the presence of the medicine in your bloodstream can often stop HIV from taking hold and spreading in your body. If you do not take PrEP every day, there may not be enough medicine in your bloodstream to block the virus. PrEP can only be prescribed by a health care provider and must be taken as directed to work.
- CDC – PrEP Resources and Guidelines
- CDC – Basic PrEP Q&A's
- CDC – PrEP for HIV Prevention
- CDC – Conversation Starters about PrEP
- CDC – Vital Signs: Daily Pill Can Prevent HIV
- CDC – Fact Sheet: Pre-Exposure Prophylaxsis (PrEP) for HIV Prevention
- CDC – Brochure: Talk to Your Doctor About PrEP
- CDC – Fact Sheet: Information about Acute HIV Infection and PrEP
- CDC – Fact Sheet: Truvada Medication Information Sheet for Patients
- CDC – PrEP Clinical Trials
- FDA – Consumer Update: FDA Approves First Medication to Reduce HIV Risk
- NIH – Antiretroviral Therapy To Reduce HIV Transmission
- VA – HIV Pre-Exposure Prophylaxis
Last revised: 12/30/2016