PrEP and PEP: Prevention of HIV Topical Map

PrEP (pre-exposure prophylaxis) is a preventive medication taken before potential exposure to HIV to substantially reduce the risk of infection; typical regimens are daily oral TDF/FTC or TAF/FTC or long-acting injectable cabotegravir. PEP (post-exposure prophylaxis) is a short 28-day antiretroviral course started after a potential recent exposure and must begin as soon as possible — ideally within 72 hours — to reduce the chance of infection.

People at substantial ongoing risk of HIV — including men who have sex with men with condomless sex, people with an HIV-positive partner not virally suppressed, people who inject drugs sharing equipment, and people with recent bacterial STIs — should be offered PrEP after baseline HIV testing and renal assessment. Local guidelines vary, so eligibility should be confirmed with sexual-health services.

For receptive anal sex, protective drug levels are typically reached after 7 days of daily dosing; for receptive vaginal sex and some genital tissues, protection may take up to 20 days of daily dosing. Because tissue pharmacokinetics differ, clinicians should counsel patients on timing and consider condoms or abstinence during the lead-in period.

PEP should be started as soon as possible and no later than 72 hours after a potential HIV exposure; effectiveness declines the longer initiation is delayed. If more than 72 hours have passed, clinicians still assess risk and may consult an HIV specialist, but standard PEP regimens are not routinely recommended after that window.

Yes — people who complete a PEP course after an exposure and remain at ongoing risk should be transitioned to PrEP; most protocols recommend HIV testing 4–6 weeks into PEP and at completion, then starting PrEP immediately if HIV-negative and renal function is acceptable. Early linkage and case management are critical to avoid treatment interruptions or inadvertent monotherapy if HIV infection is present.

Event-driven (2-1-1) dosing of TDF/FTC is highly effective for cisgender men who have sex with men and some transgender women for sexual exposures when taken correctly (two pills 2–24 hours before sex, then one pill 24 and 48 hours after the first dose), but it is not recommended for people with receptive vaginal sex because tissue drug levels differ. Providers should confirm the patient's sex, sexual practices, and suitability before prescribing 2-1-1 PrEP.

Most people experience mild transient side effects such as nausea, headache, or headache-like fatigue that typically resolve within days to weeks; clinically significant renal impairment and bone density changes are uncommon but monitored with baseline and periodic testing. Serious adverse events are rare in real-world and trial data, and the benefit in preventing HIV usually outweighs these risks for people at high exposure risk.

Long-acting cabotegravir injectable PrEP given every 2 months has demonstrated superior protection to daily oral TDF/FTC in clinical trials for cisgender men and transgender women and provides an alternative for people with adherence challenges to daily pills. Implementation requires clinic capacity for injections, HIV testing before each dose, and monitoring for potential drug–drug interactions and side effects.

Both PrEP (TDF/FTC) and PEP regimens are used during pregnancy and breastfeeding when indicated; TDF/FTC has the largest safety data and is generally recommended when the benefit outweighs any theoretical risk. Clinical management should include HIV testing, drug safety counseling, and coordination with antenatal care to monitor pregnancy and infant outcomes.

Access options include sexual-health clinics, primary care with trained clinicians, telehealth PrEP services with mail-order labs and medication delivery, community distribution through outreach programs, and some national public-health programs offering free or subsidized medication. Program-level strategies — same-day PrEP starts, pharmacy-based models, and community-based testing — reduce barriers and increase uptake.