Tirzepatide is a dual agonist: it acts on two gut-hormone receptors (GIP and GLP-1), where semaglutide acts on one. It is sold as Zepbound (weight management) and Mounjaro (type 2 diabetes). It is FDA-approved, putting it at Tier A.
What the studies found. In the SURMOUNT-1 trial, 2,539 adults took weekly tirzepatide for 72 weeks and lost roughly 16% to 22.5% of body weight, depending on dose.[1]
What’s reported as a downside. A 2024 FAERS analysis of the GLP-1 class found the same pattern of metabolic and gastrointestinal adverse-event reports — nausea and vomiting most commonly.[2] FAERS reports are voluntary and cannot prove cause.
Tirzepatide is the clearest case where price depends on dose: Zepbound single-dose vials are priced per milligram, while the pens list at one flat price. See the cost calculator and maintenance dose.