Semaglutide Half-Life: How Long It Stays in Your System
Semaglutide's elimination half-life is approximately 1 week, according to the FDA label for Ozempic. About half of a dose is still present after 7 days, and the label says semaglutide stays in the circulation for about 5 weeks after the last dose. With once-weekly dosing, steady state arrives after 4 to 5 weeks.[1]
Semaglutide half-life calculator
Estimate, not a lab result. Levels are relative: each dose is scaled so its own peak equals its mg. The shaded band is a sensitivity range, not a confidence interval.
What is the half-life of semaglutide?
Semaglutide's elimination half-life is approximately 1 week. That is the wording in the FDA-approved prescribing information for Ozempic, the once-weekly injection made by Novo Nordisk.[1] Elimination half-life is the time it takes the amount of a drug in the body to fall by half once absorption is finished. After one week about half remains, after two weeks about a quarter, and after three weeks about an eighth. The same label states that semaglutide is extensively bound to plasma albumin, a protein in the blood.[1] The half-life belongs to the molecule, so it does not change with the size of a dose. A larger dose raises the level, but the level still needs the same time to halve. The calculator above starts at 7 days, which is 168 hours, and you can edit that number. Half-life describes how fast the amount in the body declines. It does not tell you when an effect starts or fades.
How long does semaglutide stay in your system after the last dose?
The Ozempic label says that with a half-life of approximately 1 week, semaglutide will be present in the circulation for about 5 weeks after the last dose.[1] The arithmetic agrees. Each week the remaining amount is cut in half, so after five weeks only 0.5 raised to the fifth power is left, which is about 3 percent. That is a small trace, not zero, and the share keeps shrinking after week five. The table below lists the simple elimination share next to PepTrac's modeled level for a single 1 mg dose. The modeled level is higher at week one because the dose peaks one to three days after injection, so the clock for the decline starts later than the injection. Treat both columns as estimates. Your own clearance, body size, and the product you use can move the real curve, and no calculator here replaces a blood test or your prescriber's judgment.
| Weeks after dose | Simple share left | Model level (range) | Days |
|---|---|---|---|
| 1 | 50% | 0.65 (0.55 to 0.73) | 7 |
| 2 | 25% | 0.33 (0.23 to 0.41) | 14 |
| 3 | 12.5% | 0.16 (0.10 to 0.23) | 21 |
| 4 | 6.25% | 0.08 (0.04 to 0.13) | 28 |
| 5 | 3.1% | 0.04 (0.02 to 0.07) | 35 |
Why is semaglutide injected once a week?
Ozempic is dosed once weekly because its half-life is about one week.[1] When the next injection is due, roughly half of the previous dose is still present, so the level moves within a band instead of crashing to zero between doses. In PepTrac's model that band is about a factor of 1.6 from lowest to highest point once steady state is reached, which you can see in the table in the steady state section below. A drug with a half-life of hours, such as liraglutide at about 13 hours, would fall to a small fraction of its peak in a week, which is why Victoza is injected daily.[7] The label also reports similar exposure when semaglutide is injected in the abdomen, thigh, or upper arm.[1] The schedule is set by the prescriber and the label. This page explains why the interval fits the half-life and does not suggest any dose or timing.
| Drug | Label half-life | Label dosing | Build-up ratio at label interval |
|---|---|---|---|
| Semaglutide (Ozempic) | about 1 week[1] | weekly | 2.00 |
| Tirzepatide (Mounjaro) | about 5 days[5] | weekly | 1.61 |
| Dulaglutide (Trulicity) | about 5 days[6] | weekly | 1.61 |
| Liraglutide (Victoza) | about 13 hours[7] | daily | 1.39 |
How long does semaglutide take to reach steady state?
The Ozempic label states that steady-state exposure is achieved following 4 to 5 weeks of once-weekly administration.[1] That matches the general pharmacokinetic rule that repeated dosing needs about five half-lives to settle.[2] Steady state means the amount going in each week equals the amount being cleared, so the level just before each dose stops climbing. PepTrac's model shows the same pattern for repeated 1 mg doses. The level before the fourth dose is about 94 percent of its eventual plateau and before the fifth dose about 97 percent, which lines up with the label's four to five weeks. A bigger or smaller dose changes the height of the plateau, not the time needed to reach it. The model values are relative, so 1.23 means 1.23 times a single dose's own peak, not a blood concentration. Early doses build up quickly, then each added week adds less than the one before.
| Doses taken | Level before next dose | Share of plateau |
|---|---|---|
| 1 | 0.65 | 50% |
| 2 | 0.98 | 75% |
| 3 | 1.15 | 88% |
| 4 | 1.23 | 94% |
| 5 | 1.27 | 97% |
| 8 | 1.30 (range 0.95 to 1.66) | 99% |
| 12 | 1.31 (range 0.95 to 1.67) | 100% |
What happens to your level if you miss a dose?
In PepTrac's model, skipping one weekly dose roughly halves the level one week later. After eight weekly doses the level just before the next dose is about 1.30. If that dose is skipped, the level a week later is about 0.65, with a range of 0.40 to 0.93. Exactly half is no accident, because the half-life is about equal to the dosing interval. This is arithmetic about concentration, not advice about what to do. For the real instruction, the Ozempic label says that if a dose is missed, administer it as soon as possible within 5 days after the missed dose.[1] The Wegovy label gives a different rule, which depends on whether the next scheduled dose is more than 2 days away.[4] Labels differ by product and by dose, so ask your prescriber or pharmacist which rule applies to you before you act on any estimate.
When does semaglutide peak after an injection?
The Ozempic label says the maximum concentration of semaglutide is reached 1 to 3 days post dose.[1] That is a range across people, not one fixed moment. PepTrac's calculator uses 48 hours, the middle of that range, to shape the curve. The peak matters because the half-life only describes the decline. Right after an injection the level rises while the drug is absorbed from under the skin, and the decline starts after the top. This is why PepTrac's one-week level for a single dose reads 0.65 of the peak, higher than the plain 50 percent from the half-life formula: only about five days of decline have passed, not seven. If you change the peak time in a model, the single-dose curve moves a little, and the shaded band widens or narrows to show how sensitive the result is. Peak time is one more reason to treat any number here as an estimate.
Is the half-life different for Ozempic, Wegovy and compounded semaglutide?
Ozempic and Wegovy are both semaglutide injections from Novo Nordisk, and the half-life figure on this page comes from the Ozempic label, because that is where the wording was confirmed.[1] The Wegovy label text checked for this page did not state its own half-life, so none is quoted for it here.[4] Compounded products are a separate matter. The FDA states that compounded drugs are not FDA approved, so the agency does not review them for safety, effectiveness, or quality before they are marketed.[3] It also says that semaglutide sodium and semaglutide acetate are different active ingredients than the approved drugs, and that it lacks information on whether they share the approved drug's properties.[3] That means the one-week figure should not be assumed for them. If you use a compounded product, ask the pharmacy what it contains, and do not treat the label half-life as a promise about that vial.
Frequently asked questions
Does a higher dose change semaglutide's half-life?
No. Half-life is a property of how the body clears the drug, so it stays about the same at any dose. A higher dose raises the level, and the level still takes roughly a week to halve. Dose choices belong to your prescriber.
Is semaglutide gone after one week?
No. After one half-life about half the amount is still present. The label says semaglutide stays in the circulation for about 5 weeks after the last dose, with only a small share left by then.
How long after stopping do the effects fade?
Half-life describes the drug level in the body, not the strength or length of its effects. Effects can fade sooner or later than the level suggests. Ask your prescriber what to expect if you stop treatment.
Is the half-life different by injection site?
The Ozempic label reports similar exposure when semaglutide is injected in the abdomen, thigh, or upper arm. Site choice is not expected to change the half-life. Follow your product instructions for where and how to inject.
Why does PepTrac show a range instead of one number?
Real half-life and peak time vary between people. PepTrac sweeps both by 20 percent, takes the lowest and highest results, and shades that band around the estimate. It is a sensitivity range, not a statistical confidence interval.
Does this tell me when to take my next dose?
No. The calculator is educational and never suggests a dose or timing. Your prescriber and the product label set the schedule, including what to do after a missed dose.
Sources
- DailyMed, National Library of Medicine (Novo Nordisk). Ozempic (semaglutide) injection prescribing information. Accessed October 3, 2026.
- Drug Design, Development and Therapy (via PubMed Central). Contribution of Trough Concentration Data in the Evaluation of Multiple-Dose Pharmacokinetics for Drugs with Delayed Distributional Equilibrium and Long Half-Life. Accessed October 3, 2026.
- U.S. Food and Drug Administration. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. Accessed October 3, 2026.
- DailyMed, National Library of Medicine (Novo Nordisk). Wegovy (semaglutide) prescribing information. Accessed October 3, 2026.
- DailyMed, National Library of Medicine (Eli Lilly). Mounjaro (tirzepatide) injection prescribing information. Accessed October 3, 2026.
- DailyMed, National Library of Medicine (Eli Lilly). Trulicity (dulaglutide) prescribing information. Accessed October 3, 2026.
- DailyMed, National Library of Medicine (Novo Nordisk). Victoza (liraglutide) injection prescribing information. Accessed October 3, 2026.
Written and maintained by the team that builds PepTrac. Every calculator on this site runs the same tested math as the app. Read how we research, cite, and update pages in our editorial policy.
