Drug facts

How long does tirzepatide stay in your system?

By David Chen·Editor·Reviewed September 2026

What the labels say¹

The Zepbound label states that the elimination half-life is approximately 5–6 days in patients with overweight or obesity, and in patients with obstructive sleep apnea and obesity. Its overdosage section, and the Mounjaro label’s pharmacokinetics section, both put it at approximately 5 days, and the Mounjaro label adds that this is what enables once-weekly dosing.² The two brands are the same molecule, so the figures describe the same drug measured in different populations.

The long half-life comes from the molecule’s design: the label says tirzepatide carries a C20 fatty diacid that enables albumin binding and prolongs the half-life. Why that makes a weekly injection possible is explained in how tirzepatide works.

The arithmetic after a last dose¹

A half-life is the time it takes for the amount in the body to fall by half. Run that forward from the label’s 5-to-6-day figure and you get the table below. This is our arithmetic, not the label’s. The label reports a population average and does not state how long tirzepatide remains in the body after the last dose.

Five half-lives is where halving leaves about 3%, so it is the point this page uses for a rough answer: about 25 to 30 days. Read it with three caveats. It is an approximation built on an average, and the label gives clearance a coefficient of variation of about 20%, so people differ. It starts from the amount present at the last dose, which on a weekly schedule is the accumulated steady-state level, not a single injection. And a small remaining share is still an amount; the arithmetic says nothing about what any test could detect.

Where the label uses the half-life³

The slow clearance shows up in a few of the label’s practical instructions, each of which is covered on its own page:

• Missed doses. A missed dose can be taken within 4 days (96 hours); after that it is skipped. The weekly day can be changed as long as the two doses are at least 3 days (72 hours) apart. The missed-dose rule →
• Overdose. The label says a period of observation and treatment may be necessary, taking into account the half-life of approximately 5 days.
• Surgery and sedation.⁴ Because tirzepatide delays gastric emptying, the label tells patients to inform their providers before any planned procedure. It also says the available data are insufficient to say whether temporarily stopping the drug would reduce retained stomach contents. What the label says about surgery →

Pregnancy and breastfeeding⁵

This is the question where “how long does it stay in your system” matters most, so it is worth being exact about what the Zepbound label does and does not say:

• Section 8.1 says weight loss offers no benefit in pregnancy and may cause fetal harm, and to discontinue Zepbound when a pregnancy is recognized.
• Section 8.3 covers contraception: oral hormonal contraceptives may be less effective, so the label advises switching to a non-oral method, or adding a barrier method, for 4 weeks after starting and for 4 weeks after each dose increase.
• The label gives no interval for stopping before a planned pregnancy. Its counseling section says patients should tell their healthcare provider if they intend to become pregnant.

The halving table above is not a substitute for that conversation. The label’s full pregnancy and contraception wording is on tirzepatide and pregnancy.

On breastfeeding, the label reports a single-dose study of 11 lactating women given 5 mg: tirzepatide was undetectable in 164 of 171 milk samples, and the last measurable concentrations occurred 5 days after the dose. That describes milk after one dose, not blood, and not someone on weekly treatment. What the label says about breastfeeding →

How it is cleared¹

Tirzepatide is broken down rather than filtered out whole: the label describes proteolytic cleavage of the peptide backbone, beta-oxidation of the fatty diacid, and amide hydrolysis. Its metabolites leave mainly in urine and feces, and intact tirzepatide is not observed in either. Kidney and liver impairment did not change its pharmacokinetics in the label’s studies.

The drug and the effect are different questions⁶

How long the molecule stays and how long its effects last are not the same thing, and the label measures only the first. What happens to weight after stopping was tested in SURMOUNT-4: adults who had taken tirzepatide for 36 weeks and were then switched to placebo regained 14.0% over the following 52 weeks, while those who continued lost a further 5.5%. The trial is summarized on SURMOUNT-4.

The label also notes that the delay in gastric emptying is largest after the first dose and diminishes over time¹, and it links that delay to oral contraceptives, which it says may be less effective because of it.

What none of this covers

None of the labels’ pharmacokinetic figures describes a compounded preparation; they describe the molecule as the approved product delivers it. How a compounded vial differs is set out in compounded vs Zepbound, and what a vial costs per month is on the price index.

Nothing here is medical advice. This page reports what the labels state and shows arithmetic on it; when to stop, restart or plan around a medication is a decision for your prescriber. See the medical disclaimer.