How is tirzepatide dosed?

The labelled ladder

The 2.5 mg starting dose is an initiation dose rather than a therapeutic one — it exists to let tolerance develop before the ladder begins in earnest. From there the labels increase in 2.5 mg increments after at least four weeks at the current step, giving the familiar 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg sequence over roughly twenty weeks. Because the increase is authorised only after at least four weeks, staying at a step longer sits inside the labelled schedule rather than departing from it.

The maximum is 15 mg once weekly for all indications on the Zepbound label. Mounjaro states the same 15 mg adult maximum alongside a separate 10 mg maximum in pediatric patients — a distinction easy to lose when a dose figure is quoted without its population.

Why four weeks

Tirzepatide’s half-life is approximately five days, so a weekly interval accumulates toward steady state rather than reaching it immediately; roughly four weeks at a given step is what it takes to get there. That is the pharmacological reason each rung is four weeks long, and it is also why escalating faster changes the tolerability picture without reaching a different destination. The published rationale for titration across this class is that starting high raises gastrointestinal adverse-event rates without improving outcomes.

The missed-dose rule as written

Both labels state it identically: administer as soon as possible within 4 days (96 hours) after the missed dose; if more than 4 days have passed, skip it and administer the next dose on the regularly scheduled day. This is reported because it is what the labels say, and it is worth noting that it differs from every semaglutide label — a rule learned from one product in this class does not transfer to another.

To convert any of these milligram figures into syringe units for a given vial and volume, use the dosage calculator.