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An estimate from the doses and published half-lives, not a blood level. Never change a dose or a schedule because of it: ask your prescriber.
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Ozempic half-life calculator: semaglutide in your body
Ozempic's label gives semaglutide a half-life of about 1 week, so it stays in the body for about 5 weeks after the last dose. This page opens the half-life calculator on Ozempic® and the four doses its label lists, from 0.25 mg to 2 mg. Enter how many weekly shots you have taken and when you took the last one, and it estimates how much semaglutide is in your body now and when it falls to a trace. It is an estimate from the label's figures, not a blood test, and it never suggests a dose.
What does the Ozempic label say about its half-life?
The clinical pharmacology section of the Ozempic prescribing information (§ 12.3) puts it in one sentence: "With an elimination half-life of approximately 1 week, semaglutide will be present in the circulation for about 5 weeks after the last dose." It adds that "Steady-state exposure is achieved following 4 to 5 weeks of once-weekly administration."
The calculator uses exactly that half-life, 168 hours, with the absorption figures explained on the main half-life calculator page. On this page the dose choices are Ozempic's own, from § 2.2 of its label:
| Ozempic dose on the label | What the label calls it |
|---|---|
| 0.25 mg once weekly | The starting dose, for 4 weeks |
| 0.5 mg once weekly | A maintenance dose |
| 1 mg once weekly | A maintenance dose |
| 2 mg once weekly | A maintenance dose and the maximum |
Your prescriber decides which of these doses you take and when it changes.
A worked example: how Ozempic builds up at 0.5 mg
The doses in this example are illustrative. The label starts at 0.25 mg, but the calculator models one steady dose, so this example keeps 0.5 mg from the first shot. It shows the estimated amount just before each new weekly shot, against the level it settles at if the same dose continues:
| Just before | Estimated amount | Share of the settled level |
|---|---|---|
| Shot 2 | 0.23 mg | 50% |
| Shot 3 | 0.35 mg | 75% |
| Shot 4 | 0.40 mg | 87% |
| Shot 5 | 0.43 mg | 94% |
| Shot 6 | 0.45 mg | 97% |
Each week adds half of the remaining gap, because half of last week's amount is still there when the next shot lands. By the fifth week the level is within a few percent of its plateau, which is the 4 to 5 weeks the label describes.
How long does Ozempic take to leave the body?
Suppose the same person takes 8 weekly shots of 0.5 mg and then no more. In the calculator, the amount falls below 10% of its last peak about 25 days after the final shot, and below 3% after about 37 days. That is the label's "about 5 weeks", seen as a curve.
A larger dose does not change those days. A 2 mg shot starts four times higher and still halves every week, so it reaches the same share of its own peak on the same day.
What can this estimate not tell you?
- Your own blood level. The figures are averages from the label. Weight, kidney function and the injection site all shift what one person absorbs and clears.
- When side effects ease. Nausea or appetite changes do not track the curve closely, and the Ozempic label gives no level at which they stop.
- What to do about a dose. A late or missed Ozempic dose is covered by the label's own instructions and by your prescriber, not by this curve.
Frequently asked questions
How long does Ozempic stay in your system after stopping?
About 5 weeks, according to its label. In the calculator, less than 3% of the last peak is left about 37 days after the final shot.
Is the half-life of Ozempic the same as Wegovy's?
Yes. Both contain semaglutide, and both labels give a half-life of approximately 1 week. The Wegovy label words the time in the circulation differently, and the Wegovy half-life page shows how.
Why does my Ozempic level keep rising for a month?
Each weekly shot lands on what is left of the earlier ones. With a 1-week half-life, the total climbs for about 4 to 5 weeks before it levels off, as the label states. Every new dose step starts a fresh climb.
Where can I see the Ozempic dose steps?
The GLP-1 dose chart shows the Ozempic label's steps by week, with the maintenance doses marked.
Sources
- Ozempic (semaglutide) prescribing information, DailyMed: half-life, time in the circulation and steady state (§ 12.3); doses (§ 2.2).
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