HIV can be transmitted through anal sex among gay men. If one gay man is infected with HIV, the other is more likely to become infected, and the passive partner in anal sex is more likely to become infected than the active partner in anal sex. This is because the mucous membrane of the rectum is very easy to damage, and the virus can enter the body through the damaged opening. Therefore, if gay men want to have sex, it is important to use condoms correctly and avoid promiscuity. Gay men are at high risk of HIV infection. If condomless high-risk anal sex occurs, please take post-exposure prophylaxis in a timely manner. Taking blocking medication within 48 hours can block more than 95% of the infection.