Sex can cause AIDS because of the high levels of the virus in the semen or vaginal secretions of AIDS patients. Especially in patients who are not receiving antiretroviral therapy, the level of the virus is very high. When having unsafe sex with a patient, the friction of sexual contact may cause damage to the mucous membranes, and even if the damage is minor, when it comes into contact with vaginal secretions or semen containing the virus, it may lead to the risk of infection. It is important to be clean and not promiscuous, and to take safe measures when having sexual contact with patients or people whose health is not known. If you have sex without knowing the patient’s health condition or if you have high-risk sex, you should go to the hospital as soon as possible for a checkup to see if you are at risk of infection, and if necessary, you should be given antiviral medication to block the treatment in order to avoid being infected.