Pre-exposure prophylaxis (or PrEP) is when people at very high risk for HIV take HIV medicines daily to lower their chances of getting infected. A combination of two HIV medicines (tenofovir and emtricitabine), sold under the name Truvada®, is approved for daily use as PrEP to help prevent an HIV-negative person from getting HIV from a sexual or injection-drug-using partner who’s positive. Studies have shown that PrEP is highly effective for preventing HIV if it is used as prescribed. PrEP is much less effective when it is not taken consistently.
Text cited from Centers for Disease and Control and Prevention.
Click Here to read more about PrEP from the CDC.