Tirzepatide Half-Life Calculator
Tirzepatide's terminal half-life is approximately 5 days. This calculator visualizes how active levels build to steady state and decay after stopping.
Peak Level
4 mg
Half-Life
5.0 days
Steady State
~4 weeks
Full Clearance
~26 days
Tirzepatide: Dual GIP/GLP-1 receptor agonist. Available as Mounjaro (diabetes) and Zepbound (weight loss). May produce greater weight loss than semaglutide.
For educational and research purposes only. This calculator provides estimates based on standard formulas.
Always verify calculations with your healthcare provider before use. We assume no liability for dosing errors, adverse events, or outcomes resulting from use of this tool.
What tirzepatide's half-life means in practice
Tirzepatide is a dual GIP and GLP-1 receptor agonist with a terminal elimination half-life of approximately 5 days. That long half-life is engineered through fatty acid acylation that allows the molecule to bind reversibly to serum albumin. Albumin binding slows renal clearance and is what makes once-weekly dosing pharmacologically clean.
For pharmacokinetic purposes, "steady state" is the point at which the amount you take each week roughly equals the amount your body clears each week. The standard rule of thumb is that steady state takes 4 to 5 half-lives. For tirzepatide that lands at about 4 to 5 weeks of weekly dosing at a fixed dose. Every time your prescriber titrates the dose upward, you reset that clock for the new dose level, which is part of why titration steps are spaced 4 weeks apart in the SURMOUNT trial protocols.
Where the half-life matters most for users is the trough-to-peak ratio. With a 5-day half-life and 7-day dosing interval, your trough (just before the next injection) sits around 60 to 65 percent of your peak. That's why GI side effects, appetite suppression, and food noise reduction don't fluctuate wildly within the week the way they would with a shorter-acting medication.
Worked example: 10 mg weekly
Using the calculator with a 10 mg weekly dose, the curve climbs over weeks 1 through 4 before flattening into a steady oscillation. By week 4 the trough sits roughly 4x higher than after the first injection alone, which is the expected accumulation pattern for a 5-day half-life on a 7-day cadence. Once you stop, the curve takes about 4 to 5 weeks to wash out to clinically negligible levels.
Frequently asked questions
What is tirzepatide's half-life?
Tirzepatide's terminal elimination half-life is approximately 5 days (120 hours). This is the property that supports once-weekly dosing and produces relatively stable trough-to-peak ratios at steady state.
When does tirzepatide reach steady state?
Pharmacokinetic steady state takes roughly 4 to 5 half-lives, which works out to about 4 to 5 weeks of weekly dosing at a fixed dose. Each time you titrate the dose upward, you reset the steady-state clock for that new dose.
How long after my last tirzepatide dose is it still active?
After one half-life (5 days) you have 50% left. After two half-lives (10 days) you have 25%. Clinically meaningful exposure persists for roughly 4 to 5 weeks after a final dose, which is why dietary patterns often shift gradually rather than instantly after stopping.
What's the half-life difference between tirzepatide and semaglutide?
Tirzepatide approximately 5 days, semaglutide approximately 7 days. Both support weekly dosing, but semaglutide's longer tail means slightly smoother trough-to-peak transitions and slightly slower washout when stopping.
How do I time my last dose before stopping?
There's no required taper. Some clinicians lower the dose for 2 to 4 weeks to soften the appetite rebound. Others let the long half-life provide the natural taper. Discuss the plan with your prescriber.
Compare with semaglutide or open the unified GLP-1 half-life calculator.
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