Tirzepatide is one of the few compounds this site covers where the dose is not in doubt. It is an approved US medicine with two published labels, both current, both from the same manufacturer, and both giving a complete escalation schedule. The interesting thing is what happens when you put them side by side: the two products are physically identical at every strength, and they still do not have the same dose.
This page reports what the labels state, with the documents and dates. It does not recommend anything. Our guide to reading a dosing claim sets out why a labelled figure and a circulating figure are different kinds of object.
What both labels state
Sources, opened 2026-09-09: the ZEPBOUND label (DailyMed set id 487cd7e7, published 2026-09-02) and the MOUNJARO label (set id d2d7da5d, published the same day), both Eli Lilly and Company.
| MOUNJARO | ZEPBOUND | |
|---|---|---|
| Starting dosage | 2.5 mg subcutaneously once weekly | 2.5 mg subcutaneously once weekly for 4 weeks |
| Escalation | 2.5 mg increments after at least 4 weeks on the current dose | 2.5 mg increments after at least 4 weeks, until the maintenance dosage is reached |
| Maintenance | Not framed as a fixed set; increase if additional glycemic control is needed | Weight reduction and long-term maintenance: 5, 10 or 15 mg weekly. Obstructive sleep apnea: 10 or 15 mg weekly |
| Maximum | 15 mg weekly in adults; 10 mg weekly in patients aged 10 and older | 15 mg weekly |
| Timing | Once weekly at any time of day, with or without meals | Once weekly |
| Site | Abdomen or thigh; upper arm by another person; rotate sites | Subcutaneous |
Tirzepatide dosage chart, week by week
The escalation both labels describe, laid out on the fastest path the labels permit. Every "at least" is the label's; the week numbers are the minimum, not a calendar.
| Weeks (minimum) | Once-weekly dosage | Mounjaro (type 2 diabetes) | Zepbound (weight / OSA) |
|---|---|---|---|
| 1–4 | 2.5 mg | Starting dose; increase only if more glycemic control is needed (label revised 08/2026) | Starting step, not a maintenance dosage |
| 5–8 | 5 mg | Continue or increase | Lowest weight-reduction maintenance option |
| 9–12 | 7.5 mg | Continue or increase | Escalation step |
| 13–16 | 10 mg | Continue or increase; ceiling for patients aged 10+ | Maintenance option for both indications |
| 17–20 | 12.5 mg | Continue or increase | Escalation step |
| 21 onward | 15 mg | Adult maximum | Maximum; maintenance option for both indications |
Read across a row and the only thing that changes between the two products is the label's name for the step. Read down the Zepbound column and the obstructive-sleep-apnea path simply has no stop at 5 mg — maintenance for that indication is 10 or 15 mg. Each rung is held for at least four weeks, which, as the next-but-one section shows, is also how long the drug takes to reach steady state.
The identical-strengths finding
Set the two dosage-forms sections against each other and they match word for word. Both list single-dose pens and single-dose vials at 2.5, 5, 7.5, 10, 12.5 and 15 mg per 0.5 mL. Both list the same multi-dose vial and single-patient-use KwikPen presentations, down to the same concentrations: 10 mg/2.4 mL at 4.17 mg/mL for four 2.5 mg doses, 20 mg/2.4 mL at 8.33 mg/mL, 30 mg/2.4 mL at 12.5 mg/mL, 40 mg/2.4 mL at 16.7 mg/mL, 50 mg/2.4 mL at 20.8 mg/mL and 60 mg/2.4 mL at 25 mg/mL.
So the two products are not different formulations, different concentrations or different devices. At the level of what enters the body, 10 mg of Mounjaro and 10 mg of Zepbound are the same event.
What separates them is the indication — type 2 diabetes for one, weight reduction and obstructive sleep apnea for the other — and everything the indication drags along with it: which maintenance figures are named, whether a pediatric cap exists, and which warnings the label leads with. Mounjaro's warnings section carries diabetic retinopathy progression and hypoglycemia with insulin secretagogues near the top; Zepbound's leads with severe gastrointestinal reactions and acute kidney injury from volume depletion. Same drug, same milligrams, different documents.
Three ceilings, not one
The word "maximum" appears three times across the two labels with three different numbers behind it:
- 15 mg once weekly — Mounjaro in adults, and Zepbound's maximum recommended dosage.
- 10 mg once weekly — Mounjaro in pediatric patients aged 10 years and older.
- 10 mg as a floor — Zepbound's maintenance range for obstructive sleep apnea, where 5 mg is not among the listed maintenance dosages even though it is for weight reduction.
That last one is the one most likely to be lost in transmission, because it inverts the usual direction. For obstructive sleep apnea the label's lowest maintenance dosage is higher than the lowest maintenance dosage for weight reduction. A person quoting "5 mg is a maintenance dose of Zepbound" is quoting something the label says only about one of its two indications.
Tirzepatide half-life, and why the steps are four weeks
Both labels' clinical pharmacology sections give the same shape. The Mounjaro label states a half-life of approximately 5 days; the Zepbound label (effective 2026-08-28) gives 5 to 6 days in patients with overweight or obesity, including those with obstructive sleep apnea. Both state that steady-state plasma concentrations are reached after 4 weeks of once-weekly administration and that exposure rises in proportion to dose.
| Label figure | Value |
|---|---|
| Elimination half-life | ~5 days (Mounjaro); ~5–6 days in overweight/obesity (Zepbound) |
| Time to peak after injection | Median 24 hours, range 8–72 hours |
| Subcutaneous bioavailability | 80%, similar in abdomen, thigh and upper arm |
| Steady state | After 4 weeks of weekly dosing |
| Clearance | ~0.06 L/h in overweight/obesity (Zepbound) |
The four-week minimum on each rung and the four weeks to steady state are the same number, and that is not a coincidence worth ignoring: each step is held at least until the previous one has finished accumulating. The Mounjaro label also invokes the half-life in its overdose section, noting that observation may need to continue for some time because of it. For how a five-day half-life compares with research peptides measured in minutes, see our peptide half-life table.
What the escalation interval actually is
Both labels say increments come "after at least 4 weeks" on the current dose. That phrase is a minimum interval, not a schedule, and Zepbound's label makes the surrounding judgement explicit: consider treatment response and tolerability when selecting the maintenance dosage. The number of weeks is the only part of that sentence that survives being copied into a table, and it is the part that carries the least information. The same manufacturer's oral GLP-1 uses 30-day minimums instead, over six steps, laid out on our page on the Foundayo ladder.
This is the general failure this cluster keeps finding. A label figure is embedded in a decision — who is prescribing, for what indication, watching what response. Strip the decision and the figure looks like a recipe. Our page on reading a dosing claim works through the same problem on compounds that have no label at all, where there is no decision to strip because there was never a clinical one to begin with. Every presentation on the label is a ready-made solution; why that makes tirzepatide powder a different arithmetic problem, and where the unit errors come from, is on our tirzepatide reconstitution page.
What sits outside the label
Tirzepatide bought outside the pharmacy channel arrives without any of the above: without the indication that selects the ladder, without the four-week intervals attached to a prescriber's judgement, and without the contraindication both labels state — a personal or family history of medullary thyroid carcinoma, or Multiple Endocrine Neoplasia syndrome type 2. Both labels also name severe gastroparesis as a setting in which the drug is not recommended.
Both labels also make clear that the milligram figure describes a manufactured, inspected product at a stated concentration in a stated device. A lyophilized vial of stated but unverified content is a different quantity with the same units; the gap between the two is what our certificate-of-analysis guide is about, and the FDA warning-letter tracker records how the agency has treated sellers who blur it. The daily GLP-1 that preceded it runs on two label ladders of its own, set out on our liraglutide dosage page.