Pre-exposure prophylaxis, or PrEP, is a way for people who don't have HIV 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.
In several studies of PrEP, the risk of getting HIV infection was lower—up to 92% lower—for participants who took the medicines consistently than for those who didn't take the medicines. PrEP does not work nearly as well if it is not taken daily.
For those who are sexually active, no prevention strategy is 100% effective, but PrEP can be combined with other HIV prevention methods to provide even greater protection than when used alone. These include:
- Using condoms consistently and correctly.
- Getting HIV testing with your partners.
- Getting STD testing with your partners.
- Choosing less risky sexual behaviors, such as oral sex.
If you inject drugs, participating in a drug treatment program or using sterile injection equipment.
Who Should Consider Taking PrEP?
CDC recommends that PrEP is indicated for people who do not have HIV and are at substantial risk for HIV.
For sexual transmission, this includes anyone who is in an ongoing relationship with a partner who has HIV. It also includes anyone who 1) is not in a mutually monogamous* relationship with a partner who recently tested HIV-negative, and 2) is
a gay or bisexual man who has had anal sex without a condom or been diagnosed with an STD in the past 6 months; or
a 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 have bisexual male partners).
For people who inject drugs, this includes those who have injected illicit drugs in the past 6 months and who have shared injection equipment or been in drug treatment for injection drug use in the past 6 months.
For heterosexual couples where one partner has HIV and the other does not, PrEP can help protect the uninfected partner during conception and pregnancy.
People who use PrEP must take the drug every day and return to their provider every 3 months for a repeat HIV test, prescription refills, and follow-up.
Some people on PrEP have side effects like an upset stomach or loss of appetite but these are mild and usually go away in the first month.
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 postexposure prophylaxis, or PEP. PEP must begin within 72 hours of exposure. See our PEP Q&A for more information.
* Mutually monogamous means that you and your partner only have sex with each other and do not have sex outside the relationship.
What Can You Do?
Ask your health care provider about PrEP if you are HIV-negative and at substantial risk of getting HIV.
If you are precribed PrEP, take your medicine every day, report any side effects to your provider, and return for follow-up visits and HIV testing every 3 months.
If you are on PrEP, remember that the more prevention options you choose, the greater your protection. Using condoms, for example, not only adds to your HIV protection but can also prevent other STDs. See our Prevention Q&As for more prevention options.
What Can Health Care Providers Do?
Providers play a central role in increasing awareness and uptake of PrEP. They can:
Prescribe PrEP to those patients with indications for its use.
Use the guidelines and providers' supplement to get information about counseling patients who use PrEP about adherence and HIV risk reduction, including condom use.
Regularly monitor HIV infection status, side effects, adherence and sexual or injection risk behaviors for patients being prescribed PrEP.
For additional information on PrEP at APEB Oakland contact: