Does PrEP protect against other STIs? PrEP does not protect against other sexually transmitted infections (STIs) such as gonorrhea, chlamydia, herpes, or syphilis. This is why we still recommend condoms and getting tested regularly. Related articles How effective is PrEP? Is PrEP safe to use during pregnancy? What can I do if I am not in a state that Nurx serves, and my provider refuses to give me PrEP? How do I get PrEP through Nurx? How much does PrEP cost?