Interactive tool
GLP-1 Half-Life Calculator: How Long It Stays In Your System
Every GLP-1 medication leaves the body at its own pace, set by its elimination half-life. This calculator uses the published half-life from each drug's FDA label and simple exponential decay to estimate how much of a single dose is still in your system after a given number of days, and roughly when it is effectively cleared.
GLP-1 Half-Life & Clearance
Estimated drug remaining
of a single dose still in your system
- Half-life
- 6.9 days
- ~Cleared after
- 34.4 days
Half-lives at a glance
Uses published elimination half-lives from FDA labels and single-dose exponential decay. A drug is generally considered effectively cleared after about five half-lives. With ongoing weekly dosing, the medication also builds to a steady state over roughly four to five weeks, so this reflects clearance after stopping, not levels during regular use. Educational only, not medical advice.
When people ask how long a GLP-1 stays in their system, they are usually asking one of two things: how long side effects might linger after stopping, or how long the drug keeps working between doses. Both come down to the elimination half-life, the time it takes for the amount of medication in the body to drop by half. This tool applies each drug's published half-life to estimate what remains after a number of days.
The half-lives, from the labels
The four main injectable GLP-1 medications clear at very different speeds. Semaglutide (Ozempic, Wegovy, and the oral Rybelsus) has a half-life of about a week. Tirzepatide (Mounjaro, Zepbound) is about five days. Dulaglutide (Trulicity) is roughly four and a half days. Liraglutide (Saxenda, Victoza) is much shorter at about 13 hours, which is why it is dosed daily rather than weekly. Our guide to how long Ozempic stays in your system goes deeper on semaglutide specifically.
Why five half-lives is the rule of thumb
After one half-life, half the drug remains; after two, a quarter; after three, an eighth. By five half-lives only about 3% is left, low enough that the drug is considered effectively gone. For semaglutide that is roughly five weeks; for tirzepatide, about three to four weeks; for liraglutide, only two to three days. This is the same math the calculator uses, just run forward to whatever day you enter.
Clearing versus steady state
There is an important distinction this tool makes. It models a single dose clearing after you stop, which answers the common question about how long the drug lingers. During regular weekly use, the opposite is happening: the long half-life causes the medication to accumulate to a steady state over about four to five weeks, which is when the full appetite effect is reached. That gradual build-up is also why the titration schedule ramps the dose slowly, and why effects fade gradually rather than switching off after a missed dose. See the side-effects timeline for how symptoms track that curve.
What this cannot tell you
Half-life is an average from pharmacokinetic studies; your own clearance varies with kidney function, body size, and other factors. The calculator will not tell you when it is safe to stop, switch, or restart, or how long side effects will last for you specifically. Those are questions for your prescriber. Used as intended, it gives a clear, evidence-based sense of the timescale involved. Not medical advice.
Frequently Asked Questions
How long does semaglutide (Ozempic, Wegovy) stay in your system?
Semaglutide has an elimination half-life of about one week (roughly 165 hours). Because a drug is generally considered effectively cleared after about five half-lives, semaglutide takes roughly five weeks to leave your system after your last dose.
How long does tirzepatide (Mounjaro, Zepbound) stay in your system?
Tirzepatide has a half-life of about five days (roughly 120 hours), so it is largely cleared after about three to four weeks. This is why weekly dosing keeps levels steady and why effects taper gradually rather than stopping abruptly after the last dose.
What does half-life actually mean?
The half-life is the time it takes for the amount of drug in your body to fall by half. After one half-life, 50% remains; after two, 25%; and so on. By about five half-lives, only around 3% is left, which is why that point is treated as effectively cleared.
Does the medication build up over time?
Yes. With regular weekly dosing, long half-life drugs like semaglutide and tirzepatide accumulate to a steady state over roughly four to five weeks, which is when the full effect is reached. This calculator models a single dose clearing after you stop, which is what most people mean when they ask how long it stays in their system.
Not medical advice. This resource is for general education only. Medications, dosing, and treatment suitability are decisions for you and a licensed clinician who knows your full medical history.
Last updated · 5 min read
Weekly Digest
Get Evidence-Based Metabolic Health Insights Weekly
Research-backed insights on metabolism, GLP-1 science, and sustainable weight management — once a week.
Continue reading
Related articles
How Long Does Ozempic Stay in Your System?
Wondering how long does Ozempic stay in your system? Its half-life is about a week, so it takes roughly 5 weeks after your last dose to fully clear.
GLP-1 Side Effects Timeline: Week-by-Week Guide
Most side effects cluster in the first 4–8 weeks and improve as the body adapts. Knowing the timing — what tends to peak when, what tends to resolve when — changes the experience of going through it.
Semaglutide Dosing Schedule: 0.25mg to 2.4mg Week by Week
Why semaglutide is started low and raised in steps — the standard 0.25mg-to-2.4mg titration, how Ozempic differs, and what to do if a dose isn't tolerated.
Ozempic vs Wegovy: Same Drug, Different Purposes
Ozempic and Wegovy are both semaglutide — but one is FDA-approved for diabetes and the other for weight loss, and that gap drives dose, coverage, and access.