How long does tirzepatide stay in your system?

Tirzepatide has a terminal half-life of about five days, which is why it is dosed once weekly. Steady state is reached after roughly four weeks of consistent weekly dosing.

Is Mounjaro the same as Zepbound?

Mounjaro and Zepbound are both tirzepatide. They are the same molecule approved under two brand names for two different indications, type 2 diabetes and chronic weight management.

Is tirzepatide FDA approved?

Yes. The FDA approved tirzepatide as Mounjaro in May 2022 and as Zepbound in November 2023.

Tirzepatide: half-life, evidence and what trials used

Tirzepatide is a dual GIP and GLP-1 receptor agonist administered as a once-weekly subcutaneous injection.

Also known as tirz, Mounjaro, Zepbound.

Evidence and regulatory status

Approved for human use, with published phase 3 data.

Approved by the FDA as Mounjaro for type 2 diabetes and as Zepbound for chronic weight management.

Half-life

Tirzepatide has a reported terminal half-life of about 5 days. Approximately 5 days. Supports once-weekly administration. Figure taken from Mounjaro label.

What published trials used

SURMOUNT-1 randomised participants to 5mg, 10mg and 15mg once weekly, after a starting dose of 2.5mg titrated upward over several weeks.

Reported for reference only. What a trial administered under supervision is not a recommendation, and Gireta does not make one.

How much research exists

PubMed records: 2464
Tagged human: 1348
Clinical trials: 145

A PubMed search for Tirzepatide returns 2,464 records, of which 1,348 are tagged as human research and 145 are typed as a clinical trial.

Counted on 2026-09-04. Counts drift, so the exact query is linked rather than described, and you can re-run it.

Common questions

How long does tirzepatide stay in your system?: Tirzepatide has a terminal half-life of about five days, which is why it is dosed once weekly. Steady state is reached after roughly four weeks of consistent weekly dosing.
Is Mounjaro the same as Zepbound?: Mounjaro and Zepbound are both tirzepatide. They are the same molecule approved under two brand names for two different indications, type 2 diabetes and chronic weight management.
Is tirzepatide FDA approved?: Yes. The FDA approved tirzepatide as Mounjaro in May 2022 and as Zepbound in November 2023.

Sources

Mounjaro label · DailyMed, US National Library of Medicine, 2025
SURMOUNT-1 · New England Journal of Medicine, via PubMed, 2022

Related compounds

Incretin receptor agonists

Act on the GLP-1 receptor, and in some cases on the GIP and glucagon receptors as well.

Semaglutide Semaglutide is a GLP-1 receptor agonist available as a once-weekly subcutaneous injection and as a daily oral tablet.
Retatrutide Retatrutide is an investigational triple agonist of the GIP, GLP-1 and glucagon receptors, studied as a once-weekly subcutaneous injection.

Planning a schedule?

Gireta turns a compound and a cadence into a twelve-week timeline with the reconstitution maths worked out and a monthly cost.

Plan a Tirzepatide schedule

Last reviewed 2026-09-04.