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

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.

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.

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.

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).

北京市人民政府. 事前、事后分不清？六问六答全面了解艾滋病病毒暴露前/暴露后预防. https://www.beijing.gov.cn/fuwu/bmfw/jhsyfwzdzx/sjazbr/fakp/202311/t20231110_3299397.html；中国疾病预防控制中心性病艾滋病预防控制中心 (2020). 艾滋病病毒暴露后预防技术指南（试用）：「服药者可能由于不能耐受药物的副作用而停药，或者因其他原因发生漏服等情况。这些都将降低药物的预防有效性」「医生应在求询者暴露后30天和90天，分别对服药者进行HIV、HCV抗体检测随访」. https://www.chinacdc.cn/jkyj/crb2/yl/azb/jswj_azb/202410/t20241027_302131.html；重庆市疾病预防控制中心 (2024). 重庆市艾滋病暴露后预防用药24小时门诊规范化流程建设指南发布，已有多家医院提供全天候服务：「重庆市目前提供艾滋病暴露前和暴露后预防药物服务的机构已经增加至26个区县29家门诊」「能提供24小时全天候服务的门诊已经达到14家」. https://www.cqcdc.org/index.php?a=shows&catid=2270&id=3045