How long does tirzepatide stay in your system?
Short answer: tirzepatide has a half-life of about 5 days, meaning half of a dose clears roughly every 5 days. After a final dose, it takes around 25 to 30 days for almost all of it (about 97 percent) to leave your body. The same logic applies to semaglutide (Mounjaro's cousin in Wegovy and Ozempic), which has a half-life of about 7 days.
What "half-life" actually means
A half-life is the time it takes for your body to clear half of the medication in your blood. With a 5-day half-life, a dose is at roughly 50 percent after 5 days, 25 percent after 10 days, 12.5 percent after 15 days, and so on. Clinicians use a rule of thumb of about five half-lives, roughly 25 days for tirzepatide, for a drug to be essentially cleared.
Why weekly injections work
Because the half-life is close to the dosing interval, each weekly injection lands before the previous one has fully cleared. Levels build over the first few weeks and then settle into a steady rhythm: a peak in the day or two after your jab, then a slow decline until the next one. That is why the medication is taken once weekly rather than daily.
Why this explains how you feel
Many people notice a pattern across the week: appetite suppression strongest in the first days after injecting, and hunger creeping back on days 6 and 7. Others notice side effects like nausea cluster in the 48 hours after a dose, when levels peak. None of this is imaginary; it follows the curve. Seeing where you are on the curve turns a confusing week into an explainable one, and it is useful context to bring to your prescriber if side effects or returning hunger are an issue.
See your own curve, not a generic one
A generic chart shows what an average curve looks like. What you actually want to know is where you are today, based on the doses you actually took, including the late one, the skipped one and the titration change. PepLevel builds an estimated level curve from your own logged doses using published half-life values, with a marker for right now. The estimate is illustrative rather than a measurement, but it makes your week make sense at a glance, and the basic curve is free.
See what is in your system right now
Level estimates from your actual logged doses, for any injectable. Coming soon to the App Store.
Get PepLevelMedical disclaimer: this guide is general information, not medical advice. Half-life figures are published averages and individual clearance varies. Level estimates in PepLevel are illustrative only and are not a measurement of your blood levels. Always follow your prescriber's instructions.