How much does semaglutide build up with weekly dosing?

At steady state on a weekly schedule, the model's level is about 2 times what one dose gives, and it swings about 1.61:1 between the peak and the trough before the next dose. Longer gaps between doses mean less build-up and a bigger swing.

Is this chart my actual semaglutide level?

No. It is a modeled estimate from a published half-life, using the same one-compartment model as the Dose Track app. Real levels vary with body weight, injection site, kidney and liver function and other factors, and only a lab test measures them. It is not medical advice.

Semaglutide Half-Life: Peak and Steady State Chart

Q: When does semaglutide peak after a dose?

Blood levels peak about 2 days after an injection under the skin, according to Ozempic (semaglutide) label. Individual timing varies with the injection site, the amount and the person.

Q: How long does semaglutide take to reach steady state?

About 35 days (~5 weeks) of regular dosing at the same amount and interval, which is 5 half-lives. With a half-life of about 7 days, levels reach about 50% of steady state after 7 days and about 90% after 23 days (~3.3 weeks). Changing the dose or interval starts a new climb toward a new steady state.

Q: How long does semaglutide stay in your system after the last dose?

Roughly 5 half-lives, about 35 days (~5 weeks), until about 97% has cleared in the model. Half is gone about 7 days after levels start falling. Real clearance varies from person to person, and a drug can still have effects after levels are low.

Short answer: Semaglutide has a half-life of about 7 days (Ozempic (semaglutide) label) and reaches steady state after about 35 days (~5 weeks) of regular dosing. Levels peak about 2 days after an injection under the skin. On a weekly schedule the model builds up to about 2× a single dose, with a peak-to-trough swing of about 1.61:1.

What do semaglutide levels look like with weekly dosing?

The Ozempic label starts at 0.25 mg once weekly for 4 weeks, then increases to 0.5 mg once weekly. The chart holds 0.5 mg weekly from the first dose to show the build-up on its own. Source: Ozempic (semaglutide) label. Bioavailability 89% as in the app. Dashed line: 5 half-lives. Change the amount or schedule in the calculator.

When does semaglutide peak after a dose?

Levels peak about 2 days after an injection under the skin.

How long does semaglutide take to reach steady state?

With regular dosing at a fixed amount and interval, levels climb toward steady state by the same fraction every half-life, whatever the dose. At a half-life of about 7 days:

Time from the first dose to each share of steady state, semaglutide (half-life 7 days).
Share of steady state	Half-lives	Time
50%	1	7 days
75%	2	14 days
90%	3.3	23 days (~3.3 weeks)
97% (Dose Track's steady-state rule)	5	35 days (~5 weeks)

How much do semaglutide levels swing between doses?

The longer the gap between doses compared with the half-life, the bigger the swing from peak to trough and the less the levels build up. These ratios do not depend on the amount.

Steady-state peak:trough and build-up by dosing interval, semaglutide, in Dose Track's model.
Interval	Peak : trough	Build-up vs one dose
Daily	1.02 : 1	10.61×
Every other day	1.07 : 1	5.57×
Twice weekly	1.19 : 1	3.41×
Weekly	1.61 : 1	2×
Every 2 weeks	3.12 : 1	1.33×

Build-up is the accumulation ratio 1 / (1 − e^−k·τ), with k = ln 2 / half-life and τ the interval.

How long does semaglutide stay in your system?

After the last dose, about half is gone every 7 days. After 5 half-lives, about 35 days (~5 weeks), roughly 97% has cleared in the model.

Where do these numbers come from?

The FDA Ozempic label gives an elimination half-life of about 1 week and says peak concentration is reached 1 to 3 days after a dose.

Ozempic (semaglutide) prescribing information, section 12.3. DailyMed.

The curve uses the half-life, time to peak, route and bioavailability built into the Dose Track app for semaglutide, and the same one-compartment model with first-order absorption. These are modeled estimates from published half-lives, drawn with the same one-compartment model as the Dose Track app. Real levels vary from person to person, and only a lab test measures them. This is not medical advice and not a dosing recommendation; dosing decisions belong with you and your prescriber.

Vial sizes and syringe math are in the Semaglutide guide.

When does semaglutide peak and reach steady state?