Ozempic's half-life is about 7 days (Ozempic FDA label: elimination half-life approximately 1 week).
Half-life estimate, not bloodwork or dosing advice. Disclaimer.
By Austin Witherow and Mason Calvert · Last updated · Sources
| Measure | 0.25 mg once a week, after the last dose |
|---|---|
| Highest amount | 0.5 mg, 2 days after the last dose |
| 50% of that left | 9 days after the last dose |
| 10% of that left | 25.5 days after the last dose |
| 3% of that left | 37.5 days after the last dose |
| Levels off | Around day 42 |
On the example input, 0.25 mg once a week, the curve levels off around day 42; after the last dose it takes 25.5 days to fall to 10% of its final 0.5 mg peak and 37.5 days to fall to 3%.
A single 0.25 mg injection fades on the same timeline from a lower peak of 0.25 mg of semaglutide, because every dose in the model decays at the same 7-day half-life.
This is the modeled amount of the drug itself. Drug tests look for metabolites and use different, often longer, windows. Pedplot does not estimate detection times.
| Frequency | Each dose | High point | Low point | Swing |
|---|---|---|---|---|
| Weekly (open in plotter) | 0.25 mg | 0.5 mg | 0.304 mg | 39% |
| Twice a week (open in plotter) | 0.125 mg | 0.426 mg | 0.367 mg | 14% |
Each schedule name opens that curve in the plotter.
The example input adds up to 0.25 mg a week. Given once a week as one 0.25 mg injection, the modeled amount swings 39% between its high and low point; split into 0.125 mg twice a week, the swing is 14%.
The chart shows days 56 to 70 of a 10-week run, after both schedules have levelled off.
The FDA labels agree on about 7 days.
The Ozempic and Wegovy labels both give an elimination half-life of approximately 1 week and a peak 1 to 3 days after the injection; the plot uses 2 days for the peak.
They differ only on how long semaglutide stays in circulation after the last dose: about 5 weeks on the Ozempic label, and about 5 to 7 weeks after the last injectable dose of 2.4 mg or 7.2 mg on the Wegovy label.
Both labels give an absolute bioavailability of 89% after an injection under the skin. The plot draws the full injected dose, as it does for every compound.
| Compound | Half-life | Time to peak | Parent share | Levels off | To 10% after last dose |
|---|---|---|---|---|---|
| Ozempic | 7 days | 2 days | 100% (no ester) | Day 42 | 25.5 days |
| Mounjaro | 5 days | 2 days | 100% (no ester) | Day 28 | 18.8 days |
| Rybelsus | 7 days | 1 hour | 100% (no ester) | Day 36 | 23.5 days |
| Saxenda | 13 hours | 12 hours | 100% (no ester) | Day 3 | 2.5 days |
Each row uses that compound's own example input. Of these, Saxenda falls to 10% of its final peak soonest after the last dose (2.5 days), and Ozempic takes longest (25.5 days).
The plot uses 7 days, the figure from the Ozempic FDA label. The Ozempic and Wegovy labels both say approximately 1 week. At that rate the modeled amount falls to half its peak 9 days after the last injection, as the washout table shows.
After the last injection in the example input (0.25 mg once a week), the modeled amount falls to 10% of its final 0.5 mg peak in 25.5 days and to 3% in 37.5 days (about 5.4 weeks), as the washout table shows. The Ozempic label says semaglutide will be present in the circulation for about 5 weeks after the last dose, and the Wegovy label says about 5 to 7 weeks after the last 2.4 mg or 7.2 mg injection. This is drug remaining in the model, not a drug-test window.
On the example input of 0.25 mg once a week, the modeled amount levels off around day 42, as the washout table shows: from then on, each low point before an injection is within 3% of the final one. The example 8-week run gets there by its last injection.
Ozempic has a half-life of 7 days against 5 days for Mounjaro, so Ozempic is the longer-acting of the two in the model. On their own example inputs, Ozempic falls to 10% of its final peak 25.5 days after the last dose and Mounjaro 18.8 days, as the comparison table shows. Both figures come from FDA labels: approximately 1 week on the Ozempic and Wegovy labels, and approximately 5 days on the Mounjaro label.
Data quality: High. How the model works.