Pre-exposure prophylaxis for HIV prevention


Pre-exposure prophylaxis for HIV prevention, commonly known as PrEP, is the use of antiviral drugs as a strategy for the prevention of HIV/AIDS by people that do not have HIV/AIDS. PrEP is one of a number of HIV prevention strategies for people who are HIV-negative but who have a higher risk of acquiring HIV, including sexually active adults who are at increased risk of contracting HIV, people who engage in intravenous drug use, and serodiscordant sexually active couples.
The first form of PrEP for HIV prevention—emtricitabine and tenofovir disoproxil —was approved in 2012. In October 2019, the US Food and Drug Administration approved the combination of emtricitabine and tenofovir alafenamide to be used as PrEP in addition to Truvada, which provides similar levels of protection. Descovy, however, is currently approved only for cisgender males and transgender women as the efficacy has not been assessed in people at risk for HIV through receptive vaginal sex.
In December 2021, the US FDA approved cabotegravir, which is an injectable form of PrEP manufactured by Viiv Healthcare. Regulators believe it will improve medication adherence because it has to be taken just once every two months, and it will also widen adoption as it eliminates the need to hide pills or pharmacy visits for discretion.
In its 2021 guidelines, the World Health Organization recommends several options for PrEP, tailored to different populations and circumstances:
On 18 June 2025, the FDA approved the long-acting HIV prevention antiretroviral lenacapavir in the United States. The drug is branded as Yeztugo by Gilead Sciences and requires only two doses a year demonstrating high efficacy in clinical trials by offering nearly complete protection against HIV infection. As the second PrEP extended-release option following cabotegravir, lenacapavir's simplified dosing schedule could significantly improve patient access and adherence, especially for populations at higher risk of HIV. However, the global rollout may be challenged by recent funding reductions by the Trump Administration in global health funding by the United States that were expected to support lenacapavir access in lower-income countries across sub-Saharan Africa by PEPFAR. In September 2025, global partnerships set lenacapavir's HIV prevention price at US$40 per patient annually in 120 low- and middle-income countries. The WHO is planning to adopt lenacapavir in global guidelines for resource-limited settings as well as for WHO pre-qualification regulatory approval.

Medical uses

Indications for use

United States

In the United States, federal guidelines updated in 2021 now recommend healthcare providers discuss and provide information on the use of PrEP for HIV prevention for all sexually active adults and adolescents. The US Centers for Disease Control and Prevention recommends providers take a targeted sexual history of their patients to assess specific risk for HIV acquisition and suggest PrEP to the following patients:
  • Sexually active adults and adolescents who have had anal or vaginal sex in the past six months and any of the following:
  • * One or more partner with unknown HIV status and inconsistent condom use;
  • * An HIV-positive sexual partner ;
  • * A bacterial sexually transmitted infection in the past six months.
  • Patients reporting injection drug use within the last six months and any of the following:
  • * An HIV-positive injecting partner;
  • * Shared injection equipment.
Additionally, these updated guidelines recommend providers prescribe PrEP to any patient that requests it, regardless of their stated risk factors.

United Kingdom

In the United Kingdom the BHIVA/BASHH guidelines on the use of HIV pre-exposure prophylaxis 2018 recommend:
  • On-demand or daily oral tenofovir–emtricitabine for HIV-negative MSM who are at elevated risk of HIV acquisition through unprotected anal sex in the previous six months and ongoing unprotected anal sex.
  • On-demand or daily oral TD-FTC for HIV-negative MSM having unprotected anal sex with partners who are HIV-positive, unless the partner has been on AntiRetroviral Therapy for at least six months and their plasma viral load is <200 copies/mL.
  • Tenofovir alone should not be offered to MSM.
  • Daily oral TD-FTC for HIV-negative heterosexual men and women having unprotected sex with partners who are HIV-positive, unless the partner has been on ART for at least six months and their plasma viral load is <200 copies/mL.
  • Daily oral TD-FTC for heterosexual men and women on a case-by-case basis with current factors that may put them at increased risk of HIV acquisition.
  • TDF alone can be offered to heterosexual men and women where FTC is contraindicated.
  • PrEP is not recommended for people who inject drugs where needle exchange and opiate substitution programs are available and accessed by the individual.
  • PrEP with daily oral TD-FTC for HIV-negative trans women who are at risk of HIV acquisition through unprotected anal sex in the previous six months and ongoing unprotected sex.
  • Daily oral TD-FTC for HIV-negative trans women and trans men who have unprotected sex with partners who are HIV-positive, unless the partner has been on ART for at least six months and their plasma viral load is <200 copies/mL.

    Other countries

Other government health agencies from around the world have devised their own national guidelines for how to use PrEP to prevent HIV infection in those at high risk, including Botswana, Kenya, Lesotho, South Africa, Uganda, the Zambia, and Zimbabwe.

Eligibility, follow-up care, dosage

Per WHO guidelines, initiation of PrEP can be done if a person tests negative for HIV, has no signs of current HIV infection, has good kidney function and no contraindications to the medication. Once PrEP is initiated, individuals are asked to see their healthcare provider at least every three to six months. During those visits, providers should repeat testing for HIV, test for other sexually transmitted infections, monitor kidney function, and/or test for pregnancy. Individuals must test negative for HIV prior to PrEP initiation because persons infected with HIV taking PrEP medication are at risk for becoming resistant to emtricitabine. Consequently, people with HIV infection and resistance to emtricitabine will have fewer options for selecting HIV treatment medications.
Oral PrEP is typically taken daily following potential exposure. The CDC recommends follow-up visits at least every three months to provide HIV tests, medication adherence counseling, behavioral risk reduction support, side effect assessment, STI symptom assessment, and STI testing for sexually active individuals with symptoms of a current infection. Pregnancy tests should also be done every three months for woman who may become pregnant. At three months and every six months thereafter, renal function and presence of bacterial STI is assessed. Effectiveness of PrEP is associated with adherence, meaning the more consistently a person takes the medication as prescribed the greater the chance at reducing their risk for HIV.
There are two injection-based PrEP methods, with different drugs, one using lenacapavir and one with cabotegravir, each with guidelines for eligibility and initiation criteria similar to those of oral PrEP medications. However, instead of daily dosing, doses are one to six months apart. Lenacapavir is injected every six months; for initiation, in addition to injection, the same drug is also taken orally at the time of injection and one day later, as a loading dose. People who use cabotegravir receive the initial dose followed by a second dose one month later; thereafter dosing is every two months. As for all HIV PrEP, follow-up testing includes repeat HIV testing and STI screening. Those who decide to discontinue injectable PrEP may begin using oral PrEP one dosing period after their last injection.
PrEP has been shown to be effective at reducing the risk of acquiring HIV in individuals at increased risk. Studies evaluating PrEP efficacy to reduce risk of HIV infection found a linear relationship between adherence and effectiveness of medication. This means that the more closely people follow recommended dosing of PrEP, the more effective the medication is at preventing infection. However, PrEP is not 100% effective at preventing HIV, even in people who take the medication as prescribed. There have been several reported cases of people who acquired HIV despite taking PrEP. People taking PrEP may use combination prevention strategies along with PrEP, such as condoms and other protective barriers methods. If someone on PrEP acquires HIV, they may experience the signs and symptoms of HIV/AIDS.

Event-driven PrEP

Although the daily, oral dosing schedule is still recommended for all individuals taking PrEP medication for HIV infection prevention, event-driven pre-exposure prophylaxis, or ED-PrEP, is an option for men who have sex with men. ED-PrEP is also referred to as "2+1+1" dosing, because the dosing regimen involves a person taking two pills two to twenty-four hours prior to sex, one pill twenty-four hours after taking the first two pills, and a last pill taken forty-eight hours after taking the first two pills. This dosing regimen was first proven effective to reduce the relative risk of HIV infection by 86% in the IPERGAY randomized clinical trial performed in Canada and France in 2015. This has only been evaluated with Truvada and not other drugs. According to the WHO, ED-PrEP should be considered for HIV infection prevention in MSM who have relatively infrequent sex, who are able to plan sex or delay sex for about two hours, and who find this dosing schedule convenient. ED-PrEP is not recommended for use in other populations, such as women and men who have sex with cisgender women, due to the lack of safety and efficacy data available. ED-PrEP can be beneficial to help reduce the pill burden for people and decrease costs, as fewer pills are needed.