# GLP-1 Half-Life: How Long Semaglutide & Tirzepatide Last

> Published half-life and time-to-peak for semaglutide, tirzepatide, dulaglutide and more — with sources, and what it means for steady state.

Source: https://glp-1-app.com/learn/glp-1-half-life/

Education · not medical advice

## GLP-1 half-life: how long these medications actually last

Semaglutide’s half-life is about a week. That single number explains weekly dosing, why levels take a month to plateau, and why one late shot barely moves the needle.

### What “half-life” actually means

A drug’s half-life (t½) is the time it takes for the amount in your body to fall by half. It is a property of the molecule, not of you — but it is what determines how often a medication has to be taken, and how long it lingers after the last dose.

After one half-life, ~50% of a dose remains. After two, ~25%. After five, under 4% — which is why **about five half-lives** is the usual rule of thumb both for a drug washing out and for repeated doses reaching a stable level.

### Half-life of each GLP-1 and incretin medication

Population averages from published pharmacokinetic studies and regulatory labels. Individual values vary; every figure links to its source.

| Medication | Half-life (t½) | Time to peak | Dosing | Steady state | Source |
| --- | --- | --- | --- | --- | --- |
| SemaglutideOzempic, Wegovy | ~168 h(~7 days) | 24–72 h | Weekly | ~35 days | [Ozempic FDA label (DailyMed)](https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=Ozempic) |
| RetatrutideIn clinical trials — not an approved medicine | ~144 h(~6 days) | 12–48 h | Weekly | ~30 days | [Urva et al., Lancet 2022;400:1869–81 (PMID 36354040)](https://pubmed.ncbi.nlm.nih.gov/36354040/) |
| TirzepatideMounjaro, Zepbound | ~120 h(~5 days) | 24 h(median) | Weekly | ~25 days | [Mounjaro FDA label (DailyMed)](https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=Mounjaro) |
| DulaglutideTrulicity | ~120 h(~5 days) | 48 h(median) | Weekly | ~25 days | [Trulicity FDA label (DailyMed)](https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=Trulicity) |
| OrforglipronFoundayo | ~29–49 h | 4–8 h | Daily | ~6–10 days | [Foundayo (orforglipron) FDA label (DailyMed)](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8ac446c5-feba-474f-a103-23facb9b5c62) |
| Semaglutide (oral)Rybelsus | ~168 h(~7 days) | ~1 h | Daily | ~35 days | [Rybelsus FDA label (DailyMed)](https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=Rybelsus) |
| LiraglutideVictoza, Saxenda | ~13 h | 8–12 h | Daily | ~3 days | [Victoza FDA label (DailyMed)](https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=Victoza) |

“Steady state” is roughly five half-lives — the point where the amount going in each week and the amount clearing out roughly balance. Where a study reports a range rather than a single figure, the range is shown. Rows marked “in clinical trials” are not approved medicines anywhere and cannot be prescribed. All values are estimates from published averages, not a measurement of you.

### Why weekly dosing works

With a half-life near **7 days**, semaglutide never fully clears between weekly injections — each dose lands on top of what is left of the last one. Levels climb for roughly **35 days** before flattening out.

- **It accumulates.** Weekly levels stack until intake and clearance balance.
- **It plateaus.** Once at steady state, week-to-week levels look flat rather than spiky.
- **It fades slowly.** After a last dose, meaningful amounts remain for weeks.

### What a late or missed dose does

Tirzepatide’s half-life is about **5 days**, so steady state takes roughly **25 days**. A dose taken a day or two late moves the curve far less than most people expect — the long half-life is doing the smoothing.

What to do about a missed or late dose is a question for the label and your prescriber — this page describes the pharmacology, it does not tell you when to inject.

### Common questions

#### How long does semaglutide stay in your system?

Semaglutide’s published half-life is about 168 hours (7 days), so roughly five half-lives — about five weeks — pass before the great majority of a final dose has cleared. That is a population average from published pharmacokinetics, not a measurement of any individual.

#### What is the half-life of tirzepatide?

About 120 hours (5 days) for the subcutaneous injection, with peak concentration around 24 hours after a dose. Steady state is reached in roughly 25 days of weekly dosing.

#### Is there a half-life calculator?

The arithmetic is simple: after each half-life, half of what remains is gone. This page lists the published half-life for each medication so you can work out roughly how much of a dose is left after a given number of days. The Glipath app draws the same curve continuously from your own logged doses.

#### Why does it take weeks to feel a dose change?

Because levels do not jump to a new plateau immediately. After a dose increase, it takes about five half-lives — weeks for these medications — for levels to settle at the new steady state.

#### Does half-life tell me what dose to take?

No. Half-life describes how a molecule behaves in the body on average. It says nothing about what dose is right for you, which is a decision for you and your prescriber using the approved label.

### Keep reading

- [Units vs mg](https://glp-1-app.com/learn/units-vs-mg/)
- [How reconstitution works](https://glp-1-app.com/learn/how-reconstitution-works/)
- [Semaglutide reconstitution calculator](https://glp-1-app.com/calculator/semaglutide/)

Educational only — not medical advice and not a recommended dose. These are population averages from published pharmacokinetic studies, not a measurement of your body. Always follow your prescriber and the approved label.

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