HIV-blocking drugs should be taken for 28 consecutive days, and only one dose is not very useful. HIV blocking drugs are combination preparations, with emtricitabine/tenofovir + raltegravir (or dolutegravir) preferred. Adverse reactions to taking blocking drugs are recommended to consult the first doctor and be managed under his/her supervision. HIV blocking drugs are best taken within 24 hours of high-risk exposure for the best results, but not more than 72 hours, and they also need to be taken continuously for 28 days, 1-2 times a day, so taking them only once is not very useful. AIDS is mainly transmitted through sexual contact, blood contact and mother-to-child transmission. Sexually active people are advised to avoid high-risk sexual behaviors, etc.