Semaglutide vs Tirzepatide
These are the two most-searched compounds in the whole category, and they're genuinely close cousins — both weekly, both injectable, both titrated slowly upward. The questions people actually have are about how they differ mechanistically and what that means for tracking, not which is 'best' (that's a clinician's call).
Side by side
| Semaglutide | Tirzepatide | |
|---|---|---|
| Class | GLP-1 & incretins | GLP-1 & incretins |
| Form | Injection | Injection |
| Half-life | ≈ 7 days (168 h) | ≈ 5 days (120 h) |
| Storage | — | — |
| Dose units | mg, mcg, ml | mg, ml |
| FDA status | Approved | Approved |
Facts from the Stack compound library. See the full pages: Semaglutide · Tirzepatide.
How they differ
Receptor targets
Semaglutide acts on the GLP-1 receptor alone. Tirzepatide is a dual agonist — it activates both the GIP and GLP-1 receptors. That added GIP activity is the headline pharmacological distinction between them.
Titration ladders
Both climb through defined steps over months. Semaglutide's common ladder is 0.25 → 0.5 → 1 → 1.7 → 2.4 mg; tirzepatide's is 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg. Because the numbers aren't interchangeable, a log that records the dose at each step is the only reliable history.
Half-life & cadence
Both sit around a one-week half-life, so both are once-weekly and both take roughly a month to approach steady levels. A missed week halves the level rather than zeroing it — which is exactly the kind of thing an 'in your system' curve makes visible.
Brand context
Each molecule is marketed under multiple brand names for diabetes and for weight management. We never use brand names in the library — the molecule is what matters for tracking, and brands are trademarks.
Tracking either one
Whichever you log, the workflow is the same in Stack: add it once, set the schedule, and let the app handle reminders, supply projection and an "in your system" curve from the half-life. Run both? Group them into one protocol you can pause together.
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Get the appLast reviewed 2026-06-11