What If I Need To Fast?
If I need to be fasted for say a blood test or an operation, will missing a dose make me at risk of HIV infection? The occasional missed dose of Truvada is not going to cause major harm. What we can say is say, for a blood test, if you need to be fasted in the morning, it’s okay. You can get the blood test done and then after you’ve had your tests, take your medicines as you normally would. If you are fasted, say, for an operation, it’s perfectly okay to be able to take the medicine after the operation, say, if it’s six hours after you’d normally take it, that’s okay. However, if you do miss the occasional tablet, it’s not that big a deal. You will still be protected against HIV.
It’s when you start taking less than four tablets a week that the protective effect of Truvada drops off rapidly.