每次非保护状态性交是否都可以用PEP？

PEP should be used only in emergency situations.

PEP is not the right choice for people who may be exposed to HIV frequently—for example, if you often have sex without a condom with a partner who is HIV-positive. Because PEP is given after a potential exposure to HIV, more drugs and higher doses are needed to block infection than with PrEP, or pre-exposure prophylaxis. PrEP is when people at high risk for HIV take HIV medicines (sold under the brand name Truvada) daily to lower their chances of getting HIV. If you are at ongoing risk for HIV, speak to your doctor about PrEP. Also, read our Q&As on PrEP.