Q and A


Is 15 days long enough for PrEP to start working?

I’m male and I used daily PrEP for 15 days already and had vaginal sex at that time. Did PrEP already have enough time to be effective (15 days)? Thank you.


Hi, how are you?

Yes. 15 days is more than long enough for PrEP to be effective.

In general a week of daily dosing is long enough for PrEP to work. Having sex sooner than this it is recommended to start with a double dose to increase the level of PrEP in the body.



  1. Josh Peasegood

    Hi Vinh, from the last dose you can test 6 weeks after using a 4th generation antigen/antibody test.

  2. Vinh

    Thank you , so even if I am not using condom, I will be safe and no need to test ? And how long I should wait to test when Iam finish 30 day prep . Thank you


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