Both approved, both weekly, both fully trialled. The milligram numbers do not translate.
Both are approved with full phase 3 programmes. Semaglutide is a single-receptor GLP-1 agonist; tirzepatide adds GIP. The dual agonist has generally produced larger reductions, but semaglutide has the longer record including published cardiovascular outcome data.
| Semaglutide | Tirzepatide | |
|---|---|---|
| What it is | GLP-1 receptor agonist | Dual GIP/GLP-1 receptor agonist |
| Evidence tier | Clinical | Clinical |
| Route | Subcutaneous | Subcutaneous |
| Half-life | ~7 days | ~5 days |
| Vial sizes | 10/20 mg | 20/30 mg |
| Water we suggest | 2 mL, 3 mL | 1.5 mL, 2 mL |
| Reported doses | 0.25 mg, 0.5 mg, 1 mg, 1.7 mg | 2.5 mg, 5 mg, 7.5 mg, 10 mg |
| Has a schedule | Approved-label escalation | Approved-label escalation |
Semaglutide tops out around 2.4 mg and tirzepatide at 15 mg. That is not six times the effect — they are different molecules with different potency per milligram. Someone carrying tirzepatide figures over to semaglutide would be drawing several times the top trial dose.
Both step up five times at four-week intervals, for the same reason: gastrointestinal tolerability. Both schedules come from the trials rather than being reasoned after the fact, which is what separates them from most schedules on this site.