Q and A


Do I need PEP if I only took on-demand PrEP an hour before?

Hi, I have been on daily prep for HIV for 4 years. Due to covid-19 I was stopped taking my prep for 3 weeks. Yesterday I was visited by a girlfriend around 20:00 hrs so I took 2 tablets of lamivudine/tenofovir around 21:00 hrs we started kissing and we ended up having unprotected sex. Am worried since I did not wait for 2hrs to 24hrs before sex. Am I going to be ok or I should sex for PEP? Please help since am running of time for PEP.


Hi there

Don’t worry about not quite¬†being two hours. At least one of the drugs (emtricitabine) is already active within 30 minutes and the other takes much longer so an hour either way will be okay.

Please make sure you take another single pill 24 hours after the first dose, and another one 24 hours after this.

Using PrEP like this is called on demand dosing.

See here for more info: Taking PrEP on demand and: Real life examples of PrEP on demand dosing.


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