Healthy people use these kinds of therapies to try to make their immune systems stronger and to make themselves feel better in general. People who have diseases or illnesses, such as HIV, use these therapies for the same reasons. They also can use these therapies to help deal with symptoms of the disease or side effects from the medicines that treat the disease.
Several studies have shown that PrEP reduced the risk of getting HIV infection. Men who have sex with men (MSM) who were given PrEP medication were 44 % overall less likely to get HIV infection compared to those who took no PrEP medication.