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

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 official position of the Beijing Municipal People's Government's AIDS science popularization column is: preventive medication taken after exposure is called Post-Exposure Prophylaxis (English abbreviation PEP), and it should be "administered preventatively as soon as possible within 2 hours, preferably within 24 hours, and no later than 72 hours." It must also be "taken continuously for 28 days." Beyond 72 hours, starting it is no longer recommended; this is a strict time limit. The Beijing article also specifies that "taking medication regularly every day is more effective at blocking the virus than frequently missing doses." The technical guidelines from the China CDC AIDS Prevention Center state that missing doses or stopping medication on one's own will reduce the preventive effect. The guidelines require a follow-up for medication side effects during the 2nd week of starting medication, and one HIV and Hepatitis C antibody test each at 30 days and 90 days after exposure. According to a 2024 release by the Chongqing Municipal CDC, there are 29 clinics in 26 districts and counties across the city capable of prescribing pre- and post-exposure preventive drugs, 14 of which provide 24-hour services.

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

Where to get it: Designated HIV medical institutions specified by the local CDC, usually under the Department of Infection (STD/AIDS clinic). Some cities have already established 24-hour clinics, such as Chongqing. Before going, call the local CDC to ask which facility has the medication; do not waste time in the emergency department. Situations considered "exposure" include unprotected sexual intercourse, condom breakage, needle sticks, or blood contacting mucous membranes; whether or not to use medication is determined by a doctor. The medication must be taken for the full 28 days; missing doses will reduce effectiveness. Afterward, follow medical advice to undergo re-examinations at 30 and 90 days after exposure. Blocking medication is only a remedy and cannot replace routine prevention. For daily prevention and testing, see Section 1, items 30 and 31 (use condoms throughout, and go for testing if high-risk behavior has occurred).