Drug facts

Switching sellers, formulations, or molecules

By David Chen·Editor·Reviewed August 2026

Switching sellers³

This is the switch people make most often and think about least. Two vials can hold the same milligram strength at different concentrations, so a number you have been drawing to for months can be wrong on the first vial from a new pharmacy — see units and milligrams.

Read the new label before the first dose, not after. And if you are switching for price, the figure worth comparing is the true calendar month rather than the advertised one, which is what the index computes.

Switching between the injection and the tablet¹

The approved label has a section for this, and the two directions differ. From the 2.4 mg injection to 25 mg tablets: start the tablets one week after the last injection. From 25 mg tablets to the injection: start the day after the last tablet.

The gap in the first direction is the long half-life again. See oral semaglutide for what the tablet is and why its milligram numbers look so different.

Switching molecules²

Neither label publishes a conversion between semaglutide and tirzepatide. There is no table, no ratio, and no equivalent-dose statement — the schedules were established separately, in separate trials, and each label describes only its own.

So a “2.4 mg is like X mg” figure circulating online is not from either document. What the label does say is that after a break, escalation restarts lower — see a missed dose — which is the closest thing to guidance about arriving at a dose from somewhere else.

What this page is not

It is not a conversion chart, deliberately: producing one would mean inventing the number both labels decline to publish. Any change of drug or dose is a prescriber’s decision.