Drug facts

Switching from semaglutide to tirzepatide

Reviewed August 2026

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.

There is no published conversion²

Semaglutide and tirzepatide are different molecules that act on different receptors, and the milligram numbers on their labels are not on the same scale. A maintenance dose of semaglutide is 2.4 mg a week; a maintenance dose of tirzepatide is 5, 10 or 15 mg a week. The larger number is not a larger dose in any comparable sense — it is a different drug measured on its own terms.

We searched both prescribing informations end to end. The tirzepatide label does not contain the word “semaglutide” anywhere, and the semaglutide label does not contain the word “tirzepatide”. Neither contains the word “conversion”. Any chart that maps one to the other was written by somebody, and it was not written by the people who hold the label.

Each label starts at its own beginning¹

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. Semaglutide begins at 0.25 mg once weekly for four weeks, then escalates every four weeks through 0.5 mg, 1 mg and 1.7 mg to a maintenance dose of 2.4 mg, and its label likewise says the three lowest steps are not approved as maintenance doses.

Both schedules exist for the same stated reason: to reduce gastrointestinal reactions. Neither label describes a starting point that depends on what a patient was taking before.

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.

Two habits that carry over badly⁴

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, and says that if two or more consecutive doses are missed, dosing may be resumed as scheduled or the escalation schedule may be restarted. Somebody arriving from one drug with the other drug’s habit is following a rule that was written about a different medicine.

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. A move onto tirzepatide begins at 2.5 mg and climbs, so that is not a single four-week window at the start — it recurs at every step up. Pregnancy, contraception and tirzepatide covers what the label says in full.

The questions this page cannot answer⁵

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.