This is one of the most-made moves in obesity medicine: semaglutide plateaus or grates, tirzepatide's numbers beckon, and the switch question lands on a surprising fact: there is no official conversion chart, on purpose. Here is how the switch actually runs, and the one thing you must not do.
Why there is no dose-equivalence chart
Semaglutide and tirzepatide are different molecules at different receptors (GLP-1 alone versus GLP-1 plus GIP), with different potency curves; a milligram of one is not any number of milligrams of the other. Lilly's labeling and standard clinical practice therefore treat the switch as a restart: tirzepatide begins at 2.5 mg regardless of the semaglutide dose you left, then escalates on its own schedule. Patients coming from high-dose semaglutide often tolerate faster escalation, but that is clinician judgment, not a chart.
The timing
- Standard practice: take the first tirzepatide dose when the next semaglutide dose would have been due, about one week after the last semaglutide injection. No washout period beyond that gap is required.
- Both drugs have multi-day half-lives, so some overlap of fading semaglutide and starting tirzepatide is unavoidable and expected; it is why the restart dose is low.
- What you must not do: take both on an ongoing basis. Two incretin agonists stack GI effects and hypoglycemia risk with zero trial support; no legitimate prescriber runs them together.
What switchers actually experience
Three common patterns, from trial logic and clinical reporting: appetite suppression often feels stronger once tirzepatide escalates (the GIP addition is not cosmetic); GI side effects can briefly return during the new escalation even for semaglutide veterans; and the scale usually rewards the move: tirzepatide outperformed semaglutide head-to-head in the SURMOUNT-5 era of comparisons and in every cross-trial reading. Expect the transition month to feel like a mild restart, not a continuation.
The three reasons that justify the switch, and one that doesn't
- Plateau at maximum semaglutide dose with weight goals unmet: the textbook case.
- Tolerability: some people simply do better on one molecule than the other, in both directions.
- Insurance or supply reality: coverage changes decide more switches than pharmacology does.
- The weak reason: switching at month two because results feel slow. Both drugs are still escalating then; the switch resets the clock without buying anything.
Frequently asked questions
Can you take semaglutide and tirzepatide together?
No. Combining two incretin agonists has no trial support, stacks GI and hypoglycemia risks, and is not done in legitimate practice. The switch is sequential: one stops, the other starts a week later at 2.5 mg.
What dose of tirzepatide equals my semaglutide dose?
None: there is no valid conversion. Different molecules, different receptors, different curves. Every legitimate switch restarts tirzepatide at 2.5 mg and escalates from there, whatever semaglutide dose you left.
Will I regain weight during the switch?
The one-week gap and low restart dose can soften appetite suppression for a few weeks; minor fluctuation is common and temporary. Escalation restores and usually exceeds the previous effect: cross-over data favors tirzepatide.