If you may have been exposed to HIV, get PEP within 72 hours — the sooner, the better

38. If you may have been exposed to HIV, get PEP within 72 hours — the sooner, the better

Cost: A full 28‑day course of PEP can cost thousands of yuan; in most regions it must be paid out‑of‑pocket. You’ll need to rush to a hospital that same night. The hardest part is admitting you might be infected and leaving right away.

In plain terms: If you suspect you’ve been exposed to HIV, 72 hours is the hard deadline — ideally you should start PEP within 2 hours. The medication must be taken for 28 consecutive days. After 72 hours this option is no longer available, so don’t wait until the next day to decide.

Benefit: The Beijing Municipal Government’s HIV‑prevention outreach defines this as “post‑exposure prophylaxis,” abbreviated PEP. It recommends starting preventive medication “as soon as possible, ideally within 2 hours and no later than 24 hours, but not after 72 hours,” and continuing for 28 days. Beyond 72 hours PEP is not advised. This strict timeline means that acting immediately versus waiting a night can produce completely different outcomes.

Evidence grade: B

Sources: Beijing Municipal People's Government. Can't tell the difference between before and after? Six questions and six answers to comprehensively understand HIV pre-exposure/post-exposure prophylaxis. <https://www.beijing.gov.cn/fuwu/bmfw/jhsyfwzdzx/sjazbr/fakp/202311/t20231110_3299397.html>; China CDC Center for STD and AIDS Prevention and Control (2020). Technical Guidelines for HIV Post-Exposure Prophylaxis (Trial). <https://www.chinacdc.cn/jkyj/crb2/yl/azb/jswj_azb/202410/t20241027_302131.html>

Notes: Where to obtain PEP: any designated HIV‑treatment clinic affiliated with the local Chinese CDC, usually under the Infectious Diseases or STD/HIV department. Many cities now offer 24‑hour clinics; in Chongqing, for example, 29 such clinics operate across 26 districts, 14 of which are open around the clock. Call the local CDC beforehand to find a clinic with PEP on hand — don’t waste time in the emergency room. Situations considered “exposures” include unprotected sex, a broken condom, needle sticks, or blood contact with mucous membranes; only a doctor can decide whether PEP is appropriate. The full 28‑day regimen must be completed; missing doses markedly reduces its effectiveness. Follow‑up testing is required at 4–6 weeks and at 3 months as directed by your physician. This is a remedial measure, not a substitute for regular prevention; for everyday safeguards and testing, see items 30 and 31 in Chapter 1 (consistent condom use and testing after high‑risk encounters).