Ozempic vs Wegovy vs Mounjaro vs Zepbound: what's actually different
Four brand names dominate every GLP-1 conversation, but there are really only two molecules here. Understanding that single fact decodes most of the confusion.
Two molecules, four labels
- Semaglutide is sold as Ozempic (dosed for type 2 diabetes, up to 2 mg weekly) and Wegovy (dosed for weight management, up to 2.4 mg weekly).
- Tirzepatide is sold as Mounjaro (type 2 diabetes) and Zepbound (weight management), both with the same 2.5 → 15 mg ladder.
Same molecule means same mechanism, same half-life, same fundamental behavior — the brands differ in approved indication, dose ceilings, and packaging.
Mechanism: GLP-1 vs GLP-1 + GIP
Semaglutide mimics one gut hormone: GLP-1, which slows gastric emptying, increases satiety and improves insulin response. Tirzepatide adds a second agonism — GIP — making it a dual-incretin. The practical relevance shows up in the trial numbers below.
The headline trial numbers
The two pivotal weight-management trials, in one breath each:
- STEP 1 (semaglutide 2.4 mg, 68 weeks): average body-weight reduction of about 15%, versus ~2.4% on placebo.
- SURMOUNT-1 (tirzepatide, 72 weeks): averages of roughly 15% at 5 mg up to ~21% at 15 mg, versus ~3% on placebo.
Read those carefully: they’re averages of trial populations who also received lifestyle support. Individual results spread widely around every average — some participants lost far more, some far less. A benchmark is context, not a promise.
Dosing ladders and rhythm
All four are once-weekly injections with stepped titration:
| Brand | Ladder (mg) | Half-life |
|---|---|---|
| Ozempic | 0.25 → 0.5 → 1 → 2 | ~7 days |
| Wegovy | 0.25 → 0.5 → 1 → 1.7 → 2.4 | ~7 days |
| Mounjaro / Zepbound | 2.5 → 5 → 7.5 → 10 → 12.5 → 15 | ~5 days |
The half-life difference is subtle but felt: tirzepatide’s shorter half-life makes its weekly peak-trough swing slightly more pronounced, while semaglutide’s longer one smooths the week out a bit more.
What this means for tracking
Whichever brand you’re on, the tracking needs are identical: anchor the weekly shot, follow the ladder accurately, watch the level build at each step, and log side effects against the cycle. ShotLock supports all four brands (plus compounded forms) with the right ladder, the right pharmacokinetics, and the right trial benchmark for each — so switching brands mid-journey doesn’t break your history.
Informational only — not medical advice and not a recommendation of any medication. Choice of medication is a decision for you and your prescriber.