Tirzepatide Half-Life Calculator

Tirzepatide (Mounjaro, Zepbound) has a half-life of approximately 5 days (120 hours). This means it takes about 5 days for the medication concentration in your body to decrease by half.

Tirzepatide (Mounjaro, Zepbound) typically reaches peak concentration 8-72 hours after injection, with most people experiencing the strongest effects 1-3 days after their shot.

The calculator uses a clinically-validated one-compartment pharmacokinetic model based on published data from FDA prescribing information. While accurate for population-level estimates, individual responses vary based on metabolism, body composition, and other factors.

With a half-life of about 5 days, tirzepatide takes roughly 25 days (about 5 half-lives) to clear almost completely after the last dose. The calculator visualizes this decay curve for your dose.

Medication levels rise to a peak in the first 1-3 days after a dose and then decline through the week. Appetite suppression is strongest near the peak, and appetite often returns toward the end of the dose week as levels fall. Tracking levels alongside meals and symptoms makes these patterns visible.

The GLP AI app includes this medication level chart alongside dose tracking, the GLP-1 Meal Score, and a side-effect log, so you can see levels, meals, and symptoms on one timeline. This calculator is for education only and does not provide medical advice.

Half-life is the time it takes for your body to eliminate 50% of the medication. Semaglutide has a half-life of ~7 days, while tirzepatide has a half-life of ~5 days. This long half-life is why you inject weekly—the medication stays in your system long enough to provide continuous effects between doses. Understanding half-life helps you predict when levels will be highest (strongest effects) and lowest (time for next dose).

Most people feel the strongest effects 1-3 days after injection, when medication levels peak. This is when appetite suppression is most powerful, but it's also when side effects like nausea or fatigue are most likely. The graph shows your personalized peak time based on your dose and body weight. Effects become more predictable after reaching steady state (4-5 doses).

Your medication levels fluctuate throughout the week. They're highest 1-3 days after injection (peak) and lowest just before your next dose (trough). This creates a predictable pattern: stronger appetite suppression and more side effects at peak, potentially more hunger and fewer side effects at trough. Tracking this pattern can help you optimize meal planning, exercise timing, and social activities.

Never adjust your medication dose or schedule without consulting your healthcare provider. This calculator is for educational purposes only and does not provide medical advice. However, you can share your results with your doctor. If you experience severe side effects or notice your levels drop significantly before the next dose, your provider may consider adjusting your dosing interval (e.g., injecting every 5 days instead of weekly).

Yes! Compounded semaglutide and tirzepatide use the same active ingredients as brand-name medications (Ozempic, Wegovy, Mounjaro, Zepbound), so they have identical pharmacokinetics. Simply select the medication type (semaglutide or tirzepatide) and enter your custom dose. The calculations will be accurate regardless of whether your medication is branded or compounded.

Semaglutide (Ozempic, Wegovy) has a longer half-life (~7 days) compared to tirzepatide (Mounjaro, Zepbound, ~5 days). This means semaglutide levels fluctuate less between doses and stay elevated longer. Tirzepatide levels drop faster, which may result in more noticeable appetite fluctuations toward the end of your dosing cycle. Both medications are highly effective—the choice depends on your individual response and provider recommendation.

No. This calculator is for educational and informational purposes only. It is not FDA-approved, not a medical device, and not a substitute for professional medical advice, diagnosis, or treatment. The calculations are based on population averages and may not reflect your individual response. Individual metabolism, medical conditions, and other factors affect how your body processes medication. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding medication or health. If you think you may have a medical emergency, call your doctor or emergency services immediately.