Definition
Half-life is the time it takes for the amount of a drug in your blood to fall by half. Steady state is when levels stay stable from dose to dose. Together they explain why GLP-1 changes take weeks to settle and weeks to wear off.
Half-lives across the GLP-1 family are very different. Your own GLP-1 lasts 1.5 to 2 minutes. Liraglutide (Saxenda) lasts about 13 hours. Orforglipron (Foundayo) lasts about 29 to 49 hours. Tirzepatide (Mounjaro, Zepbound) lasts about 5 days. Semaglutide (Ozempic, Wegovy, Rybelsus) lasts about 1 week. The longer the half-life, the less often you take it.
Because each dose adds to what is still in your body, levels climb for a while before they level off. The labels give the timing: about 4 to 5 weeks for semaglutide, 4 weeks for tirzepatide and about 1 week for orforglipron. That is one reason a new dose step can feel different for a few weeks, and why the labels space the steps 4 weeks or 30 days apart; see dose titration.
It works in reverse too. The Ozempic label says semaglutide stays in circulation for about 5 weeks after the last dose, and advises stopping at least 2 months before a planned pregnancy. At GLP-1 SOS this is why we tell people the gut can take weeks to feel normal after a pause or a stop.
In the Lab
- Why you may feel “not normal” months after quitting a GLP-1
- Why you feel sick on injection day (and the day after)
- How long before a GLP-1 starts working (appetite and weight)
- How long nausea lasts after a GLP-1 injection
From the people behind the Lab
You do not have to figure this out alone.
GLP-1 SOS is the daily companion made for life on a GLP-1. Plain answers like this one, a support team that replies to real questions from real people, and daily formulas like GLP-1 SOS Daily Gut Relief, designed around the side effects that come with the medication. The GLP-1 Lab is our free education arm: no login, no paywall, no hype. Side effects are part of the road. Suffering through them is not.
Sources (4)
- Ozempic (semaglutide) injection, Prescribing Information. Novo Nordisk, revised May 2026.
- Zepbound (tirzepatide) injection, Prescribing Information. Eli Lilly, revised August 2026.
- Foundayo (orforglipron) tablets, Prescribing Information. Eli Lilly, revised July 2026.
- Saxenda (liraglutide) injection, Prescribing Information. Novo Nordisk, revised February 2026.
Reviewed by the GLP-1 SOS editorial team · Education, not medical advice · Talk to your prescriber about your dose and your symptoms.
