What is a medication's half-life?
Half-life is how long it takes for half a dose of a GLP-1 to clear from your body — semaglutide is ~7 days and tirzepatide is ~5 days, which is why both are dosed weekly.
Half-life is how long it takes for half a dose of a GLP-1 to clear from your body — semaglutide is ~7 days and tirzepatide is ~5 days, which is why both are dosed weekly. Half-life matters for three reasons: how often you dose, how long side effects linger after stopping, and how long the drug keeps working if you miss a shot. Semaglutide's ~7-day half-life means a missed weekly dose still has meaningful drug level on board — Ozempic's instructions say take it within 5 days of the missed dose. Tirzepatide is similar but slightly shorter. It also means stopping the medication is not instant: appetite changes typically return over 4–6 weeks as the drug fully clears.
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