Ozempic Half-Life Calculator
Ozempic is semaglutide with a half-life of about 1 week, among the longest of any GLP-1. Whether you are starting, switching, or stopping, see your estimated level at any day.
Free · instant chart · no sign-up or email · built on the Ozempic FDA label
Ozempic half-life chart: estimated mg in your body, day by day
Estimated semaglutide in your body, day 56 after your first dose
steady rhythm: ~1.5 mg peak, ~0.96 mg trough
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Quick answer: Ozempic's elimination half-life is approximately 1 week: a last injection falls to half in about 7 days, a quarter in 14, and below 5% of the steady level in about 5 weeks. Building up, levels reach steady state in about 5 weeks. Ozempic, Wegovy, and the Rybelsus tablets are all semaglutide, so a switch between them continues the same clock rather than restarting it.
Educational estimate only, not medical advice. Individual pharmacokinetics vary, and blood level is not the same thing as appetite effect. Never change your dose or schedule without your prescriber.
The Ozempic half-life arithmetic
Ozempic is semaglutide, with an elimination half-life of about 1 week and peak levels 1 to 3 days after a dose, per the FDA label. On the label schedule (a weekly injection), levels reach steady state about 5 weeks after the first dose, and after a last dose they fall below 5% of that steady level in about 5 weeks.
Between scheduled doses, levels swing between a peak and a trough of about 62% of that peak, which is why the calculator's chart looks like a sawtooth rather than a flat line. The label also reports that 89%of each dose is absorbed into circulation; the calculator's mg figures build that in.
What the Ozempic label says about a missed dose
The Ozempic label instructs that a missed dose be administered within 5 days of the missed dose; after that, skip it and resume the regular schedule.
That window is the half-life doing the work: with about 1 weekof half-life, a late dose still lands on a meaningful base. This is the label's instruction to prescribers, not our advice; if you have missed a dose, your own label and prescriber are the authority.
Switching between Ozempic and Wegovy: the clock carries over
Because Ozempic and Wegovy are the same molecule, moving between them is a dose change, not a drug change, from your body's point of view. The semaglutide already on board keeps declining on its one-week half-life while the new dose schedule builds on top of it, which is why prescribers typically slot the first dose of the new brand into the old weekly rhythm.
The label's 5-day missed-dose window, the most generous of the weekly GLP-1s, is the same arithmetic: with a one-week half-life, even a several-day delay lands on a substantial base. How to time any switch is your prescriber's call; the curve above is the reason the timing is forgiving.
FAQ
How long does Ozempic stay in your system?
About 5 weeks to fall below 5% of the steady level (about 5 weeks on this calculator's curve), because semaglutide's half-life is approximately 1 week. Semaglutide's own label language for the injectable form puts it in circulation about 5 to 7 weeks after a last 2.4 mg dose.
Does Ozempic leave your system faster than Wegovy?
No. Ozempic and Wegovy are both semaglutide, so they clear at exactly the same rate. Wegovy doses run higher, which means more semaglutide on board at every point, but the percentage decline and the weeks-to-clear are identical.
Why does Ozempic feel weaker right before the next dose?
Two things stack. By the end of the week your level really is at its trough, about 62% of the post-dose peak. But blood level is not the same as felt effect: appetite suppression has its own timetable, and receptors adjust, so the day-6 dip many people report is real without meaning the medication is gone.
Does a higher Ozempic dose take longer to leave your system?
Not meaningfully. Ozempic is eliminated proportionally: the amount cleared per day is a fixed fraction of what remains, so every dose falls along the same percentage curve on the same timeline. A higher dose means more semaglutide at every point, not a longer goodbye.
Are these numbers my actual blood levels?
No. The curve is a population estimate built from the FDA label's median half-life and absorption figures: anyone who took the same doses on the same days would see the same chart. Individual metabolism runs faster or slower than the median, so treat it as the shape and rough scale of your levels, not a measurement.
Is this calculator free, and do I need to sign up?
Yes, it is free, and no sign-up or email is required. You see the full curve and the estimated clearance timeline instantly. The GlucoPal iOS app it comes from is also free to download.
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Sources
This free calculator is built and maintained by GlucoPal, the free iPhone app for tracking GLP-1 weight loss medications. All pharmacokinetic figures were read directly from the current FDA label on DailyMed on 27 August 2026.
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