Semaglutide is the one GLP-1 medicine whose half-life appears on four current labels, in three forms — weekly injection, daily tablet, and two brands of each — and all of them agree: approximately one week. Where the labels part company is on the tail: OZEMPIC says semaglutide is in the circulation for about five weeks after the last dose, WEGOVY says five to seven. This page sets out the label statements with their dates, why the tablet and the injection share a half-life but not a dose, and what the one-week figure means for missed doses and the washout the labels ask for before pregnancy.
The label doses, research-vial arithmetic and syringe units are on the semaglutide dosage page; the compound itself is covered in Medibact's Semaglutide guide.
What each label states
| Label (read 2026-09-26) | Half-life | In the circulation after the last dose | Steady state |
|---|---|---|---|
| OZEMPIC injection (Novo Nordisk, revised 01/2025) | approximately 1 week | about 5 weeks | 4 to 5 weeks of weekly doses |
| WEGOVY injection and tablets (Novo Nordisk, revised 06/2026) | approximately 1 week | about 5 to 7 weeks after 2.4 mg or 7.2 mg injected, or 25 mg by mouth | average 75 nmol/L on 2.4 mg, 230 nmol/L on 7.2 mg, 77 nmol/L on 25 mg tablets |
| RYBELSUS and OZEMPIC tablets (Novo Nordisk, DailyMed 2026-08-19) | approximately 1 week | about 5 weeks after the last tablet | 4 to 5 weeks of daily tablets |
The labels name the reason for the long half-life: semaglutide is more than 99% bound to albumin, which, in the WEGOVY label's words, "results in decreased renal clearance and protection from degradation". The clearance it reports, about 0.05 L/h, is roughly a litre a day from a volume of distribution of about 12.5 L.
Why five weeks for one and seven for the other
Each week halves what remains of the last dose:
| Weeks after the last dose | Share of the last dose remaining | What the labels say at this point |
|---|---|---|
| 1 | 50% | — |
| 2 | 25% | — |
| 3 | 12.5% | — |
| 4 | 6.3% | — |
| 5 | 3.1% | OZEMPIC and the tablets: "about 5 weeks" |
| 6 | 1.6% | — |
| 7 | 0.8% | WEGOVY upper end: "5 to 7 weeks" |
| 8.6 (2 months) | 0.3% | All three: stop at least 2 months before a planned pregnancy |
The labels do not say what threshold "present in the circulation" means. What the arithmetic shows is that WEGOVY's two extra weeks are two more halvings, and that its higher doses start from a higher level: the label's own steady-state figure for 7.2 mg (about 230 nmol/L) is roughly three times the 2.4 mg figure (about 75 nmol/L), and a threefold higher start takes about 1.6 half-lives longer to fall to the same level. These are this site's reading of the label numbers, not a statement in the label.
Tablet and injection: one half-life, two absorptions
The tablets and the injection release the same molecule, and once it is in the blood it is cleared at the same rate. What differs is how much of each dose arrives:
| Form (WEGOVY and RYBELSUS labels) | Absolute bioavailability | Peak concentration | Dose |
|---|---|---|---|
| Injection | 89% | 1 to 3 days after the dose | weekly |
| WEGOVY and OZEMPIC tablets | about 1% to 2% | about 1 hour after the dose | daily |
| RYBELSUS 3, 7 and 14 mg | about 0.4% to 1% | about 1 hour after the dose | daily |
By those percentages, 25 mg taken daily puts roughly 0.25 to 0.5 mg a day, or 1.75 to 3.5 mg a week, into the blood, against about 2.1 mg from a weekly 2.4 mg injection. The WEGOVY label's steady-state figures — 77 nmol/L on 25 mg tablets and 75 nmol/L on 2.4 mg injected — land in the same place. The label's switching rule starts the 25 mg tablets one week after the last 2.4 mg injection, which is one half-life. The label also notes that concentrations on the tablets vary more between people, and that some people with type 2 diabetes on the tablets may have concentrations below the therapeutic range. The GLP-1 dosage chart sets the tablet and injection doses of every approved product side by side.
What the half-life means for the missed-dose rules
The labels' missed-dose instructions read differently once the half-life is applied to them (arithmetic by this site; the rules themselves are the labels'):
- OZEMPIC injection allows a missed dose within 5 days. A dose due on day 7 and given on day 12 comes when about 30% of the previous dose is still present.
- WEGOVY injection gives the missed dose if the next is more than 2 days away, which is the same 5-day window.
- WEGOVY injection, two or more doses missed: the label restarts the escalation at a lower dose. Three weeks after the last injection about 12.5% of it remains, so the next dose meets little of the previous level.
- WEGOVY tablets: a missed tablet is skipped and the next taken the following day. With a one-week half-life and daily dosing, one tablet is about one seventh of the weekly intake and its absence moves the level by a few percent.
Against tirzepatide and retatrutide
| Molecule | Half-life | Source | Share left at 7 days |
|---|---|---|---|
| Semaglutide | about 1 week | OZEMPIC, WEGOVY and RYBELSUS labels | 50% |
| Tirzepatide | about 5 days; 5–6 in obesity | MOUNJARO and ZEPBOUND labels | 38–45% |
| Retatrutide | about 6 days | phase 1b trial (no label) | 44.5% |
Semaglutide has the longest half-life of the three and the only one stated consistently across oral and injected forms. Tirzepatide's half-life page works its two label wordings; retatrutide's sets out how thin its single published figure is.
For research vials
Semaglutide has a molecular weight of about 4,114 g/mol (PubChem CID 56843331). Research-market semaglutide carries no pharmacokinetic data of its own, and none of the figures above describes it: they describe Novo Nordisk's product. The half-life does not depend on concentration, so the units per dose are set by the vial and the water alone — the semaglutide reconstitution page works the common vial sizes, and the calculator's semaglutide setting any other.
What is not established
The labels give one rounded half-life and no range between people; they do not define the threshold behind "present in the circulation"; the steady-state concentrations are averages from population models. The week-by-week shares, the missed-dose readings and the tablet-versus-injection delivery figures are arithmetic from label numbers and are not measurements. Nothing on this page is a dose, a schedule or advice on stopping or restarting a medicine; that belongs with the prescriber.
Sources and dates
Opened 2026-09-26 through DailyMed (NLM) and openFDA: OZEMPIC injection prescribing information, Novo Nordisk (set id adec4fd2-6858-4c99-91d4-531f5f2a2d79, revised 01/2025), sections 2, 8.3 and 12.3; WEGOVY injection and tablets prescribing information, Novo Nordisk (set id ee06186f-2aa3-4990-a760-757579d8f77b, revised 06/2026), sections 2.4, 2.5, 8.3 and 12.3; RYBELSUS and OZEMPIC tablets prescribing information, Novo Nordisk (set id 27f15fac-7d98-4114-a2ec-92494a91da98, DailyMed version of 2026-08-19), sections 8.3 and 12.3; PubChem compound record 56843331. Repackager copies of the same labels were not used. Remaining shares, delivery estimates and the missed-dose readings are arithmetic by this site. Corrections go to the contact page.