What is PEP?

Post-exposure prophylaxis (PEP) is an emergency drug that you can take after having sex with someone to reduce your chances of becoming HIV positive. You must take this as soon as possible after intercourse. It must be taken within 72 hours but is most effective if taken within 24 hours. PEP consists of a combination of three HIV medications which you have to consistently take for 28 days post potential exposure to HIV. When PEP is taken, the HIV drugs get into the bloodstream and the genital and rectal tissues. If there is HIV in the body, the drugs can prevent HIV from replicating within the body’s immune cells, and help to prevent a permanent infection from developing. PEP can reduce the risk of getting HIV by more than 80%

Drug resistance

A person with low adherence who acquires HIV while taking PEP could develop resistance to the drugs in PEP. If a person’s HIV becomes resistant to the PEP drugs, those same HIV drugs may not work for treating their HIV.

Side effects 

HIV drugs can cause side effects, such as nausea, fatigue and diarrhea. The HIV drugs that are recommended for PEP in Canada are generally well tolerated and associated with minimal side effects.

Please see: https://www.catie.ca/en/fact-sheets/prevention/ post-exposure-prophylaxis-pep for more information.