Self-help is actually the use of antiretroviral drugs to prevent HIV infection by blocking the entry of HIV into the body within 72 hours of infection. If possible, HIV blocking drugs should be taken within 2 hours after a high-risk behavior to maximize the effect of blocking. If this is not possible within 2 hours, you should take the medication within 48 hours, which may also have a blocking effect. If it is more than 48h, you can take the medication within 72h and have the hope of successful blockade by taking a complete cycle. The general HIV blocking cycle is 28 days, and after stopping the medication, continuous testing of HIV antibodies should be performed, and HIV infection can be completely ruled out after 6 months.