PEP stands for post-exposure prophylaxis. It’s like emergency contraception but for HIV, because it can prevent you from becoming HIV-positive when taken after a potential sexual exposure to HIV. It’s a 28-day medication regimen involving the same drug used as PrEP plus another HIV treatment drug. It must be started within 72 hours of the potential HIV exposure, and is most effective when started as soon as possible, ideally within the first 24 hours. We prescribe it for free, like all our services.

If you are taking PrEP every day as prescribed and have waited for it to reach full efficacy in your system, you already have a maximum level of protection from HIV, so you would not need to start PEP if you were potentially sexually exposed to HIV. If you have missed a lot of doses of PrEP and then have a potential sexual exposure to HIV, it’s worth reaching out to your PrEP provider to find out whether they think you need to start PEP.”

“Can a person with HIV on treatment with an undetectable viral load transmit HIV?

No, they cannot. A person who is on effective HIV treatment and whose viral load is undetectable cannot transmit HIV to their sexual partners, regardless of whether they use condoms together or whether their sexual partners use PrEP. This groundbreaking development in HIV prevention is publicized with the slogan U=U, which stands for undetectable equals untransmittable. For more information, see Prevention Access Campaign’s FAQ on their website.

Someone in a relationship with a person living with HIV who has an undetectable viral load may still choose to use PrEP to reduce their or their partner’s anxiety about the idea of HIV transmission, even though there is no actual chance of transmission, or to give the HIV-negative partner a sense of control over HIV prevention in the relationship.