Per FDA prescribing information, semaglutide (Ozempic, Wegovy, Rybelsus) has an elimination half-life of about one week, so it takes roughly five weeks to be largely cleared after your last dose. Tirzepatide (Mounjaro, Zepbound) and dulaglutide (Trulicity) both have half-lives of around five days, also taking about four to five weeks to mostly clear. Liraglutide (Victoza, Saxenda), the once-daily option, has a much shorter half-life of about 13 hours and is largely gone within a few days. These are general pharmacokinetic figures, not a personal guarantee, actual clearance varies by kidney function, body composition and other individual factors.
Key takeaways
- A drug's half-life is how long it takes blood levels to drop by half; it takes roughly five half-lives to be considered largely cleared.
- Weekly injectables (semaglutide, tirzepatide, dulaglutide) have long half-lives designed for once-a-week dosing, and linger for weeks after stopping.
- Daily liraglutide has a much shorter half-life and clears within days.
- How long a GLP-1 lingers matters for side-effect timing, surgery planning, drug switching, and pregnancy planning, always through your care team, not on your own.
What does "half-life" actually mean?
A drug's elimination half-life is the time it takes for the concentration in your blood to drop by half. It's not a cliff edge where the drug suddenly disappears, it's a gradual decline. A commonly used rule of thumb is that after about five half-lives, a drug is considered largely cleared from the body (roughly 97% gone), which is the estimate behind the "weeks to clear" figures below. GLP-1 drugs are designed with long half-lives on purpose: it's what allows once-weekly dosing to keep levels steady, instead of needing a shot every day.
| Medication | Elimination half-life | Approximate time to largely clear |
|---|---|---|
| Semaglutide (Ozempic, Wegovy, Rybelsus) | ~1 week | ~5 weeks |
| Tirzepatide (Mounjaro, Zepbound) | ~5 days | ~4-5 weeks |
| Dulaglutide (Trulicity) | ~5 days | ~4-5 weeks |
| Liraglutide (Victoza, Saxenda) | ~13 hours | ~2-3 days |
These figures come from FDA prescribing information for each product and reflect population averages from clinical pharmacology studies, not a fixed number for every person. Individual clearance can vary with kidney function, body weight and other factors, so treat the "weeks to clear" column as a general estimate rather than an exact countdown.
Why does it matter how long a GLP-1 lasts?
The half-life isn't just a trivia point, it has a few practical implications, all of which are decisions for your prescriber rather than something to plan solo:
- Side-effect timing. Because levels decline gradually, side effects like nausea from a dose or a dose increase can take time to fully settle, and if you stop the medication, effects like appetite suppression fade gradually over roughly the same weeks-long window rather than all at once.
- Surgery and anesthesia planning. GLP-1s slow gastric emptying, which can raise aspiration risk under anesthesia. Because the drug lingers for weeks, this is a timing conversation to have with your surgical and anesthesia team well before a scheduled procedure. Our GLP-1 drug interactions guide covers this in more detail.
- Switching between GLP-1 drugs. When moving from one GLP-1 to another, your prescriber factors in how long the first drug is still active in your system when setting the new starting dose. See our dosing guide for how switching is generally handled.
- Pregnancy planning. Because these drugs take weeks to clear, a washout period is something your prescriber may factor into pregnancy planning. This is a clinical decision that depends on your specific medication and situation, always made with your prescriber, not a do-it-yourself calculation.
How the "weeks to clear" estimate is calculated
The weeks-to-clear figures in the table use the standard pharmacology approximation that a drug is largely cleared after about five half-lives. For semaglutide, a roughly one-week half-life multiplied by five lands close to five weeks. For tirzepatide and dulaglutide, a roughly five-day half-life multiplied by five comes out to about 25 days, rounded here to four to five weeks to account for some individual variation. For liraglutide's much shorter 13-hour half-life, five half-lives is under three days. This is a standard estimation method used across pharmacology, not a number specific to GLP-1s, and it describes when a drug is largely gone, not the exact moment every last trace disappears.
Does a longer half-life mean a "stronger" or "better" drug?
Not directly. A long half-life is mainly a convenience feature, it's what allows semaglutide, tirzepatide and dulaglutide to be dosed once a week instead of daily, which keeps blood levels steadier and is easier for most people to stick with. It isn't a measure of how effective a drug is or how much weight loss to expect; that comes down to the specific molecule, its receptor activity, and the dose, not simply how long it lingers. Liraglutide's much shorter half-life is why it's dosed daily rather than weekly, not a sign that it works less well within its own approved use. Our GLP-1 medications guide compares approved options on the factors that actually drive results.
It's also worth separating "half-life" from "detection window" as a concept. Some people ask how long a GLP-1 would show up on a drug test; that's not a relevant concern here, GLP-1 medications aren't part of standard drug-testing panels, and half-life in this context is purely about how long the medication is actively present and working in your system, which matters for the clinical reasons covered above rather than for testing.
Frequently asked questions
How long does semaglutide stay in your system?
Semaglutide (Ozempic, Wegovy, Rybelsus) has an elimination half-life of about one week, according to FDA prescribing information. Using the common rule of about five half-lives to reach a level generally considered mostly cleared, semaglutide takes roughly five weeks to be largely out of your system after your last dose.
How long does tirzepatide stay in your system?
Tirzepatide (Mounjaro, Zepbound) has an elimination half-life of about five days per FDA prescribing information, which works out to roughly four to five weeks to be largely cleared after the last dose.
How long after stopping a GLP-1 is it gone?
It depends on the drug's half-life. Weekly injectables like semaglutide, tirzepatide and dulaglutide linger for roughly four to five weeks after the last dose because of their long half-lives, while daily liraglutide clears in a few days. These are general pharmacokinetic estimates, not a guarantee for every individual, since clearance can vary with kidney function, body composition and other factors.
Why does it matter how long a GLP-1 lasts?
The half-life affects how long side effects can persist after a dose, how surgical and anesthesia teams plan around aspiration risk, how long a washout period might be considered before certain procedures or before pregnancy, and how doses are spaced when switching between GLP-1 drugs. These are all decisions for your prescriber and care team, not something to plan on your own.
Sources & further reading
- U.S. Food & Drug Administration, prescribing information for Ozempic/Wegovy/Rybelsus (semaglutide), clinical pharmacology section.
- U.S. Food & Drug Administration, prescribing information for Mounjaro/Zepbound (tirzepatide), clinical pharmacology section.
- U.S. Food & Drug Administration, prescribing information for Trulicity (dulaglutide), clinical pharmacology section.
- U.S. Food & Drug Administration, prescribing information for Victoza/Saxenda (liraglutide), clinical pharmacology section.