If I am not at ongoing risk for getting HIV, can I take PrEP only when I’m at risk?
Pre-exposure prophylaxis, commonly known as PrEP, is a groundbreaking prevention strategy that has emerged as a game-changer in the fight against HIV. However, the daily PrEP regimen may not suit everyone.
Taking PrEP pills only when you are at risk for getting HIV is known as “on-demand” PrEP.
It is also known as “intermittent,” “non-daily,” “event-driven,” or “off-label” PrEP use.
The type of “on-demand” PrEP that has been studied is the “2-1-1” schedule. This means taking 2 pills 24 hours before sex, 1 pill 24 hours after the first dose, and 1 pill 24 hours after the second dose.
There is scientific evidence that the “2-1-1” schedule provides effective protection for gay and bisexual men* when having anal sex without a condom.
We don’t know how “on-demand” PrEP works for heterosexual men and women, people who inject drugs, and transgender persons.
The Canadian PrEP guideline states that on-demand PrEP using Truvada (TDF + FTC) can be considered as an alternative form of PrEP for gay and bisexual men* only. This could be a good option for men who know in advance when they will have sex. There is no evidence to support the use of on-demand PrEP by other populations. For people who have vaginal (or frontal) sex and people who use drugs, it is important to take PrEP every day and not miss any pills.
Anyone considering PrEP should consult their health care provider. You can learn more about PrEP by making an appointment with our PrEP clinic here.
* The term “gay and bisexual men” is used to describe men who identify as gay or bisexual, as well as men who have sex with men who do not identify as gay or bisexual.
