PEP must be taken within 72 hours (three days) and to be most effective should be taken within 24 hours.

PEP must be taken exactly as instructed by a medical professional and for 28 days. 

  • If you skip a dose or fail to complete the full month as this makes it less likely to work
  • Don't double a dose if you miss one
  • If you miss a dose and you remember in less than 24 hours, take the next one as soon as you remember
  • If you miss more than 48 hours of PEP, you should stop taking it.

The medication now used for PEP is a single tablet called Truvada and two tablets of raltegravir.