On Demand PrEP or Event Based Dosing
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Page last reviewed 11.5.2023
The most common way to take PrEP is to take it daily, which means one pill taken at approximately the same time every day. On-demand PrEP using is shown to be highly effective for gay and bisexual men. PrEP on an event bases (on-demand) is currently only recommended for cis-men who have sex with men. This option might be most appropriate for people who have fewer HIV-related risk situations (analsex without condom) and those who have sex less than twice a week and those with predictable sex lives.
How to take PrEP on event basis?
On-demand PrEP is also known as event-based PrEP or PrEP 2-1-1. It involves taking two tablets 2 to 24 hours before engaging in sex, taking a single tablet 24 hours after the first two, and another tablet 24 hours after that.
In the case you continue having sex more than one session:
- Take two pills 2-24 hours before having sex
- Then continue taking one pill each day at approximately the same time
- Continue this until you have had 2 sex-free days.
![An explanation as a diagram of how to use on-demand PrEP.](https://hivpoint.fi/wp-content/uploads/2022/02/PrEP-on-demand-1024x718.png)