Most compounds we cover have no official dose, only forum lore. Tirzepatide is the exception: as Zepbound and Mounjaro it carries an FDA label with an exact titration schedule, and its trial program reported results dose by dose. That makes this page mostly a documentation job. What the label says, what each dose produced in trials, and what changes when the source is a lyophilized vial instead of a factory-filled pen. Nothing here is medical advice; it is a summary of the published record.
Per the Zepbound label, everyone starts at the same place and moves up slowly:
| Phase | Dose | Duration |
|---|---|---|
| Start | 2.5 mg once weekly | 4 weeks |
| First step | 5 mg once weekly | at least 4 weeks |
| Optional increases | +2.5 mg per step (7.5, 10, 12.5…) | at least 4 weeks per step |
| Maximum | 15 mg once weekly | maintenance |
Two details people miss. The 2.5 mg dose is explicitly a starting dose, not a maintenance option; the label treats 5 mg as the floor for staying put. And the 4-week minimum between increases is a hard interval, because the schedule exists to manage side effects rather than to build suspense.
The 72-week trial behind the obesity approval reported mean weight change by dose: 15.0% at 5 mg, 19.5% at 10 mg, and 20.9% at 15 mg, against 3.1% on placebo. The step from 5 to 10 mg buys most of the additional effect; the step from 10 to 15 buys much less. That diminishing curve, familiar from every drug in this class, is worth knowing because the gray market’s instinct is always that more is better, and the trial data says the middle dose already captures most of the result.
Gastrointestinal side effects are the dose-limiting reality of every GLP-1 agonist, and they concentrate at dose increases. The titration schedule is the tolerability mechanism, which is exactly why the most common research-market mistake is skipping it. A buyer with a 30 mg vial and a forum protocol faces no pharmacist, no prescriber, and no pen that physically limits the dose. The schedule survives in the gray market only if the buyer chooses to follow it, and the trial evidence exists only for the doses and intervals above.
The approved product ships as pre-filled pens and single-dose vials in exact strengths. Research vials ship as lyophilized powder labeled 10, 15, 30, or 60 mg, which hands the buyer two jobs the pharmacy normally does. First, the arithmetic: reconstituting and drawing a specific milligram dose. A 10 mg vial with 2 ml of bacteriostatic water gives 5 mg/ml, so a 2.5 mg dose is 0.5 ml, which reads 50 units on a U-100 insulin syringe. The peptide calculator does this for any combination. Second, the verification: that arithmetic assumes the vial contains what the label claims, and the published record says label misses are routine in this market. Check the batch on the tirzepatide leaderboard, where 272 tracked vendors carry 2,813 published third-party tests, before trusting the milligrams printed on a sticker.
Per the label: start at 2.5 mg weekly for 4 weeks, move to 5 mg, and increase in 2.5 mg steps no faster than every 4 weeks if needed, with 5, 10, and 15 mg as the maintenance doses studied in trials.
It was not studied as a maintenance dose; trials used it only as the four-week on-ramp. The lowest dose with 72-week results is 5 mg, at 15.0% mean reduction in SURMOUNT-1.
Take the missed dose within four days, otherwise skip it and resume the regular schedule. Beyond that, restarting after a long gap generally means retitrating, which is a prescriber conversation for the approved product.
The molecule and the titration pattern are the same; the difference is indication, with Mounjaro approved for type 2 diabetes and Zepbound for weight management and related conditions.
Depends entirely on your concentration. At 5 mg/ml (a 10 mg vial with 2 ml of water), 2.5 mg is 50 units on a U-100 syringe. At 10 mg/ml it is 25 units. Run your own numbers through the calculator rather than borrowing anyone else’s.
Tirzepatide dosing is the best-documented in the entire peptide market, so the open question is never what the schedule says; it is whether your vial matches its label. The tirzepatide buying guide covers vetting vendors by their published record, and the retatrutide dosage guide covers its unapproved cousin, where no label exists at all.
PeptideCensus Editorial is the research team behind the independent peptide lab-result index. Every article is built from published third-party data - trial publications, lab reports, and regulatory records - with every number linked to its source. We don't test, we don't sell, and commissions never touch scores or rankings.
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