What is Pre-Exposure Prophylaxis (PrEP)?
Pre-exposure prophylaxis, or PrEP, is a new HIV prevention method in which people who do not have HIV infection take a pill daily to reduce their risk of becoming infected. The pill, called Truvada®, contains two of the many medications that can be used to treat people who already have HIV. These medications prevent HIV from making copies of itself and turning into an infection that’s spread throughout your body. In this way PrEP medicines can help keep the virus from establishing a permanent infection. So, PrEP is a way for people who are at very high risk of getting HIV to lower their risk by taking a daily pill. PrEP is only meant for people at very high risk for getting HIV because they may often be exposed to the virus—for example, someone who is HIV-negative but has an HIV-positive partner and doesn’t consistently use condoms.
In 2012, the U.S. Food and Drug Administration (FDA) approved the use of the drug Truvada® as PrEP to be taken once daily and used in combination with safer sex practices to reduce the risk of sexually acquired HIV infection in adults who do not have HIV but are at high risk of becoming infected.
Taking medicine before exposure to a germ or a virus is nothing new. For example, public health officials often advise travelers to take a medication before they visit areas where malaria is common. However, the use of medication to prevent HIV infection has only recently been studied.
Does PrEP work?
Studies have shown that PrEP provides a high level of protection against getting HIV for gay and bisexual men, heterosexual men and women, and injection drug users, if the daily medication is taken consistently.
Results from two studies of PrEP, released in July 2011 (the TDF2 study and the Partners PrEP study) showed that daily oral doses of two specific antiretroviral drugs can be used to prevent transmission of HIV from men to women and from women to men. This follows findings of the iPrEx study among men who have sex with men (MSM), reported in November 2010, which found that daily oral doses of the same two antiretroviral drugs taken by HIV-negative study participants reduced, but did not eliminate, the risk of getting HIV.
In addition, in June 2013, published results from the Bangkok Tenofovir Study showed that daily oral doses of one of the two antiretroviral drugs used in other PrEP studies reduced the risk of getting HIV among injecting drug users.
In all of these studies, people who took the drugs consistently—enough that regular blood tests showed detectable levels of the drug in their systems—had much higher levels of protection than those who did not. Specifically:
- iPrEx: PrEP reduced the risk of getting HIV by 44% among all the study participants, and by more than 90% among men with detectable levels of the drug in their blood.
- Partners PrEP: PrEP reduced the risk of getting HIV by 75% overall, and by 90% in people with detectable levels of the drug in their blood.
- Bangkok Tenofovir Study: PrEP reduced risk of getting HIV by 49% overall, and by 75% in participants with detectable levels of the drug in their blood.
What medications are used in PrEP?
A combination of two medications (tenofovir and emtricitabine) sold under the name Truvada® is approved by the FDA for daily use as PrEP for people at very high risk of getting HIV infection through sexual exposures. The same combination of medications is also recommended for people at very high risk of getting HIV through needle-sharing injection drug use. PrEP can only be prescribed by a health care provider and must be taken as directed to work.
Can anyone use PrEP?
For some individuals at very high risk for HIV, PrEP may represent a much-needed additional prevention method—but it will not be right for everyone. PrEP is an intensive approach that requires strict adherence to daily medication and regular HIV testing. You and your healthcare provider should consider the following factors in deciding whether PrEP is right for you:
- Only people who are HIV-negative should use PrEP. An HIV test is required before starting PrEP and then every 3 months while taking PrEP.
- PrEP should never be seen as the first line of defense against HIV. PrEP is most effective when combined with other prevention efforts like consistent condom use and safer injection practices.
- PrEP involves taking daily medication consistently and frequent visits to a healthcare provider.
- PrEP medications can cause side effects like nausea in some people. These side effects can be treated and are not life threatening.
- PrEP may also be an option for HIV-negative women whose partners have HIV infection during conception, pregnancy, or breastfeeding.
Guidance on PrEP use
CDC has issued the following guidance on the use of PrEP among different populations:
- MSM: In January 2011, CDC published interim guidance for physicians on HIV Pre-Exposure Prophylaxis for Men Who Have Sex with Men to help guide clinical practice as formal U.S. Public Health Service guidelines are being developed.
- Heterosexuals: In August 2012, CDC published interim guidance for clinicians considering the use of PrEP for the prevention of HIV infection in heterosexually active adults. This guidance included recommendations similar to those for MSM, as well as new recommendations for women who may become pregnant while taking PrEP and to couples in which one partner is HIV-positive and the other is HIV-negative.
- Injecting Drug Users: In June 2013, CDC published an update to interim guidance for physicians on the use of PrEP for injecting drug users. This guidance recommends that PrEP be considered as one of several prevention options for people at very high risk of getting HIV from injecting illegal drugs.
For more information, visit CDC’s PrEP Resources page.
Where can I get PrEP?
You can seek PrEP from your doctor or a local HIV clinic. Your local public health department can refer you to healthcare providers that specialize in treating and preventing HIV.
Who pays for PrEP?
Private and public health insurance plans often cover the cost of PrEP. Alternatively, if you are eligible, your healthcare provider may be able to get Truvada for you at no cost from the drug’s manufacturer through its PrEP-specific medication assistance program. To be eligible, you must be a U.S. resident (you need not be a citizen or current visa holder) who meets the low-income cutoff and has no health insurance or no PrEP coverage under your health insurance. Your local health department may also be able to direct you to other kinds of medication assistance programs.
Frequently Asked Questions
Since PrEP is effective, why do I need to bother with risk-reduction strategies? Can’t I just take a pill and be safe?
Like all prevention methods, PrEP is not 100% effective. Therefore, it will provide the most protection when used with—not instead of—condoms, safer sex practices, use of clean injection equipment, and other HIV prevention methods. PrEP adds another layer of protection. 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.
Are there other ways for HIV-negative people to prevent HIV by taking medication?
Postexposure prophylaxis (PEP) also uses a combination of specific HIV drugs to prevent HIV, but PEP is used after single events rather than to reduce risk over the long term. For example, PEP may be used after a sexual assault, after a healthcare worker is exposed on the job, or after an episode of unprotected sex or needle-sharing injection drug use. PEP is taken for only 28 days immediately after a potential exposure and must begin within 72 hours to be effective.
Who pays for PrEP?
Private and public health insurance plans often cover Truvada for PrEP. If you are eligible, your health care provider can get Truvada for you at no cost from the drug’s manufacturer through its PrEP-specific medication assistance program. Eligible patients are US residents (they need not be citizens or current visa holders) who meet the low-income cutoff and have no health insurance or no PrEP coverage under their health insurance. Your local health department may also be able to direct you to other kinds of assistance programs.
Where can I get PrEP?
You can seek PrEP from your doctor or a local HIV clinic. Your local public health department can refer you to health care providers that specialize in treating and preventing HIV.
- CDC PrEP Resources Page
- CDC – PrEP: A New Tool for HIV Prevention
- CDC – Q&A: CDC's Clinical Studies of Pre-Exposure Prophylaxis for HIV Prevention
- CDC – Fact Sheet: Proven Prevention Methods
- CDC – Statement on FDA Approval of Drug for HIV Prevention
- CDC - CDC Statement on Results of iPrEx Trial Examining PrEP for HIV Prevention among MSM
- CDC – Study Shows That A Daily Dose of HIV Medication Reduces Infection Risk among People Who Inject Drugs
- FDA – Consumer Update: FDA Approves First Medication to Reduce HIV Risk
- NIH – Daily Dose of HIV Drug Reduces Risk of HIV Infection
- NIH – iPrEx study results and Q&A
- HIV Prevention Trials Network
- CDC - Talk to Your Doctor About PrEP
- AIDS Foundation of Chicago - My PrEP Experience
- Project Inform - PrEP
Immediate Cautions for MSM Considering PrEP as an HIV Prevention Strategy (scroll down page)
Last revised: 09/27/2013