Zepbound is built to last. Its drug, tirzepatide, carries a fatty-acid chain that binds to a blood protein and slows its removal, which is why one shot covers a week [1]. That also means it doesn't vanish when you stop. Here's what the label says, and what simple arithmetic adds. For the drug itself, see the Zepbound guide.
The label's half-life is about 5 days
A half-life is the time it takes for half of a drug to leave your blood. Zepbound's label puts tirzepatide's at "approximately 5-6 days in patients with overweight or obesity, and in patients with OSA and obesity" [1]. Its overdose section rounds it to "approximately 5 days." Mounjaro, the same molecule for type 2 diabetes, gives "approximately 5 days, enabling once-weekly dosing" [2].
After a shot, levels peak in about a day (24 hours on average, with a range of 8 to 72 hours, per the label) and then fall slowly through the week [1]. That slow fall is what lets a weekly dose keep working between injections.
From half-life to "out of your system": about a month, by our math
The label stops at the half-life. It doesn't print a time when tirzepatide is gone. A common rule of thumb in pharmacology is that a drug is mostly cleared after about five half-lives, when roughly 3% is left. Here's that arithmetic with a 5-day half-life:
| Days after the last dose | Share of the last dose left |
|---|---|
| 0 | 100% |
| 5 | 50% |
| 10 | 25% |
| 15 | 12.5% |
| 20 | 6.25% |
| 25 | 3.1% |
| 30 | 1.6% |
Our arithmetic: each 5 days halves the amount. With a 6-day half-life, the same points fall at 6, 12, 18, 24, 30 and 36 days. Half-life from the Zepbound label [1].
This is a simplification. After months of weekly doses, the starting level is a steady-state level, not a single dose, and people differ. Use the table as an estimate, not a guarantee. The useful takeaway: tirzepatide is mostly gone within about a month, and semaglutide takes a few weeks longer.
Why the label cares: overdose, and birth control pills
The half-life shows up in two practical places on the label. In an overdose, it says observation and treatment may be needed for a while, "taking into account the half-life of tirzepatide of approximately 5 days" [1].
The second is birth control pills, and it's often misread. The concern isn't how long tirzepatide stays in you. Zepbound slows stomach emptying, which can reduce how much of a pill gets absorbed. With a single 5 mg dose, peak levels of the estrogen in a combined pill fell 59%. The label says the delay "is largest after the first dose and diminishes over time," so its advice covers the weeks after starting and after each dose increase, not the weeks after stopping [1]. Pregnancy planning has its own considerations; see can you take a GLP-1 while pregnant?
Zepbound clears faster than Wegovy or Ozempic
Semaglutide's half-life is about a week, so it stays longer. Wegovy's label says semaglutide "will be present in the circulation for about 5 to 7 weeks after the last" dose [3]. Ozempic's label says "about 5 weeks" [4]. That's why Wegovy's label tells people to stop at least 2 months before a planned pregnancy "to account for the long half-life of semaglutide" [3].
| Drug | Half-life | Time in circulation after the last dose |
|---|---|---|
| Zepbound, Mounjaro (tirzepatide) | About 5 days (5 to 6 days in obesity) | Not stated; about a month by our arithmetic |
| Wegovy (semaglutide) | About 1 week | About 5 to 7 weeks |
| Ozempic (semaglutide) | About 1 week | About 5 weeks |
Zepbound, Mounjaro, Wegovy and Ozempic prescribing information, section 12.3 [1] [2] [3] [4].
For a side-by-side of the two brands beyond timing, see Zepbound vs Wegovy.
Do side effects last as long as the drug?
No study has measured how long side effects last after the last dose, so there's no number to give. The label does say most nausea, vomiting and diarrhea happened while the dose was rising and "decreased over time" [1]. Since the drug fades over a few weeks, effects tied to it would be expected to fade with it, but that's reasoning, not trial data. The side effects themselves are covered in Zepbound side effects, and tiredness in does Zepbound make you tired?
Weight is a different story. It doesn't wait for the drug to clear entirely: in trials, regain started within weeks of switching to placebo and continued for months. See what happens when you stop a GLP-1.
Compounded tirzepatide hasn't been measured
Compounded tirzepatide is the same molecule, so you'd expect a similar half-life, but no one has measured it in compounded products. Compounded tirzepatide isn't FDA-approved, the FDA doesn't review it for safety or effectiveness, and it doesn't check its quality before it ships. See is compounded tirzepatide safe? Doses for the brand are in Zepbound dosage, and the molecule is on the tirzepatide guide.
Weighing programs on price? The brand Wegovy and Zepbound self-pay programs lineup sets 21 of them side by side, each with its true monthly cost.