How a missed or late dose increases the risk of resistance

Figure 3: Drug levels with good adherence

The curved line in this figure shows that average drug levels increase after you take your meds and then steadily drop until the next dose.

Average levels need to be high enough to be active against HIV for the whole dose period. They need to stay above low levels when drug resistance can occur. They are also low enough to minimise the risk of side effects.

Figure 4: A missed or late dose increases the risk of resistance

Missing or being late with a drug dose lets the drug levels fall to a level where resistance can develop. The more often you are late, the greater the chance of resistance.

Last updated: 1 September 2024.