Semaglutide half-life: how long it stays in your system

Half-life is the time it takes for the amount of a drug in the body to fall by half once absorption is over. For semaglutide, both FDA labels put it at about 1 week. That one number explains the weekly schedule, the slow build-up over the first month and the long tail after the last dose.

Semaglutide pharmacokinetics at a glance

(Novo Nordisk, Jun 18, 2026) (Novo Nordisk, Jun 1, 2026)

Two notes on the table. The Wegovy label says steady-state exposure rose in proportion to dose up to 7.2 mg once weekly. And injection site does not change much: exposure was similar in the abdomen, thigh and upper arm.

How much is left after a single dose

The table below comes from the site’s model. It shows a single 1 mg dose so the numbers read as fractions. The “modeled amount” column includes absorption (peak around day 1.5); the “left by decay alone” column is pure halving every 7 days.

With absorption included, the model gives 0.5241 mg-equivalents left on day 7 and 0.0328 on day 35 from a 1 mg dose. Those are close to the pure-decay figures because semaglutide is absorbed within days but eliminated over weeks.

How long semaglutide stays in your system

A common rule of thumb is that a drug is mostly gone after about 5 half-lives, when roughly 97% has been cleared. For semaglutide, 5 half-lives is about 35 days, or 5 weeks. The labels say the same thing in their own words:

• Wegovy: semaglutide “will be present in the circulation for about 5 to 7 weeks after the last injectable dose of 2.4 mg or 7.2 mg” or the last 25 mg tablet. (Novo Nordisk, Jun 18, 2026)
• Ozempic: semaglutide “will be present in the circulation for about 5 weeks after the last dose.” (Novo Nordisk, Jun 1, 2026)

The labels do not explain why the two ranges differ, and the Wegovy figure is tied to its higher maintenance doses. Talk to your prescriber before stopping, pausing or restarting.

Steady state and accumulation

Because a new dose arrives before the last one is gone, the amount in the body builds up over the first weeks at a dose. Under the site’s model, the weekly accumulation ratio for semaglutide is 2.0000. In plain terms: at steady state, the amount in the body at any point in the week is about twice what a single dose would leave at that same point. It follows directly from half of each dose remaining after 7 days.

The Ozempic label states steady state is reached after 4 to 5 weeks of weekly dosing. (Novo Nordisk, Jun 1, 2026) The Wegovy ladder changes dose every 4 weeks, so during escalation the body is usually still approaching one plateau when the next step starts. The chart below shows that pattern.

• Weekly dose (published steps)
• Modeled amount (mg-eq)
• Stable window

Each 4-week step lifts the modeled curve, and the curve only levels out during the hold at 2.4 mg. Try other schedules in the semaglutide plotter, or map the label steps to dates with the titration calculator.

Build-up and wash-out week by week

The same halving drives both the climb to steady state and the fall after the last dose. At a fixed weekly dose, the share of the eventual steady-state level reached by the end of each week is 1 minus 0.5 raised to the number of weeks. After stopping, the amount falls by half each week.

The build-up column lands at about 94% to 97% by weeks 4 and 5, which lines up with the Ozempic label’s statement that steady state is reached after 4 to 5 weeks. (Novo Nordisk, Jun 1, 2026) The wash-out column mirrors it, which is consistent with the labels’ figure of about 5 weeks or more in circulation after the last dose.

Half-life and the label’s timing rules

Several label rules involve time windows. The labels do not explain their reasoning, but the windows are easier to remember next to a 1-week half-life.

(Novo Nordisk, Jun 18, 2026) (Novo Nordisk, Jun 1, 2026)

The full ladders are in the semaglutide dosage chart.

Injection vs tablet

The tablet and the injection deliver the same molecule, but very different amounts reach the blood. Absolute bioavailability is 89% after subcutaneous injection and about 1% to 2% for the tablet, which uses an absorption enhancer (SNAC) in its formulation. (Novo Nordisk, Jun 18, 2026) That is why the tablet ladder runs from 1.5 mg to 25 mg daily, while the injection ladder runs from 0.25 mg to 2.4 mg weekly. The label’s 5-to-7-week clearance figure covers the 25 mg tablet as well.

What the model does and does not show

The site’s charts use a one-compartment model with first-order absorption (the Bateman function). It uses a 7-day half-life and a 36-hour tmax, a point inside the label’s 1-to-3-day range. Output is a relative amount in mg-equivalents with bioavailability set to 1, not a blood concentration. Real levels vary from person to person. Full details are on the model card, and approvals and trial data are on the semaglutide hub.