Drug facts
Switching from semaglutide to tirzepatide
If you are switching from one compounded seller to another and want the mark on the syringe, work it out from your own vial — the concentration is set by the pharmacy that made it, and it is the number that changes.
Quick answer
Neither label publishes a dose equivalence between the two molecules. There is no table saying that 1 mg of semaglutide corresponds to some amount of tirzepatide, because no such table exists in either prescribing information. Each drug has its own initiation dose and its own escalation schedule, and the dose you were taking of one does not name a dose of the other. Our guide to compounded tirzepatide explains why vial labels and concentrations can differ across pharmacies. Neither price nor a matching syringe mark establishes that two prescriptions are equivalent.
There is no published conversion12
Semaglutide and tirzepatide are different molecules that act on different receptors, and the milligram numbers on their labels are measured on the same scale. The approved injections have separate maintenance doses that depend on the product and the condition being treated. Milligrams alone cannot determine an equivalent dose.
The Wegovy label gives instructions for switching between its own tablets and injection. Those instructions apply to semaglutide formulations. The two labels provide no dose conversion between semaglutide and tirzepatide.
Switching sellers usually means a new price and new billing terms. Among the sellers we work with, the SnagRx review records $162 a calendar month at every dose, the Shed review $299 a calendar month at the starting dose and the SkinnyRx review $299 a calendar month at every dose. We may earn a commission from these sellers, and the full index orders every seller by price alone.
Each label starts at its own beginning12
Both labels describe a schedule that begins at an initiation dose and climbs. Tirzepatide begins at 2.5 mg once weekly for four weeks — a dose the label states plainly is not approved as a maintenance dose — then moves to 5 mg, and may rise in 2.5 mg steps after at least four weeks on the current dose, to a maximum of 15 mg. The weekly Wegovy injection schedule starts at 0.25 mg and steps through 0.5 mg, 1 mg and 1.7 mg at four-week intervals. Adult weight-management maintenance is 1.7 or 2.4 mg. The label permits 7.2 mg for adults who tolerate 2.4 mg for at least four weeks and have a clinical indication for further weight reduction.
Both schedules exist for the same stated reason: to reduce gastrointestinal reactions. Neither label gives a starting dose based on the dose of the other molecule.
Switching sellers, same molecule3
This is the switch this site sends people toward, so it is the one we owe the clearest account of. Moving between compounded sellers can change the mark on your syringe without changing your dose at all.
A compounded vial’s concentration — milligrams of drug per milliliter of liquid — is chosen by the pharmacy that prepares it, and it is not standardized between them. Your dose is a quantity of drug. The syringe measures liquid. So the same milligram dose drawn from a more concentrated vial is a smaller mark, and drawn from a less concentrated one, a larger mark. A number you remember from your last vial can be badly wrong on the first vial from a new seller.
The number to work from is the concentration printed on the vial in front of you, and the instruction that arrived with it. The dose-in-units tool takes that concentration and shows the arithmetic; units, milligrams and milliliters explains why the two numbers exist at all.
On the label — Mounjaro / Zepbound
Each presentation has its own strength and instructions. Zepbound is available in single-dose and multi-dose presentations. Check the device or vial dispensed to you and follow its instructions.
In a compounded vial
Concentration is set by the compounding pharmacy. Two vials of the same milligram strength can hold different concentrations, so a switch between sellers can change the mark on the syringe while your prescribed dose stays exactly where it was.
Two habits that carry over badly12
The missed-dose rule is not the same rule. The tirzepatide label gives a window: a missed dose may be taken within four days — 96 hours — and after that it is skipped, with the next dose taken on the regular day. The semaglutide label frames it differently. For two or more missed weekly Wegovy injections in a row, the current prescribing information calls for restarting the escalation at a lower dose. Ask your prescriber how to restart.
An escalation restarts the contraception clock, and a switch often means escalating. The tirzepatide label advises patients using oral hormonal contraceptives to switch to a non-oral method, or add a barrier method, for four weeks after starting and for four weeks after each dose escalation. If your prescriber increases your dose, the four-week period starts again. Pregnancy, contraception and tirzepatide covers what the label says in full.
The questions this page cannot answer1
What dose to move to, whether to move at all, whether a gap between the last dose of one and the first dose of the other is wanted, and what your own history makes sensible — none of these are on a label, and none of them are answerable by a page that has never met you. They belong to your prescriber.
What this page can tell you is what the published documents contain, so that you can recognize a number that came from somewhere else. When a chart converts one molecule into the other, it is worth asking who wrote it and from what.