Tirzepatide

Mounjaro · Zepbound

FDA-approved dual GIP/GLP-1 agonist for type 2 diabetes, obesity, and obstructive sleep apnea.

FDA approvedWeight & Metabolism

Overview

Tirzepatide is a once-weekly injectable that combines GIP and GLP-1 receptor activity. In SURMOUNT-1, the 15 mg dose produced ~21% mean weight loss over 72 weeks, and it outperformed semaglutide head-to-head in SURMOUNT-5.

Mechanism of action

Dual agonist at GIP and GLP-1 receptors, enhancing insulin secretion, reducing appetite and food intake, and slowing gastric emptying.

Benefits & evidence ratings

~15–21% mean weight loss over 72 weeks (SURMOUNT-1)A Established / approved

Greater weight loss than semaglutide 2.4 mg head-to-head (SURMOUNT-5)B Human clinical data

Reduced apnea–hypopnea index in OSA with obesityA Established / approved

Dosing

Doses show what has been studied or discussed — not guidance. Always follow your prescriber.

Source	Dose	Frequency	Duration	Route
Zepbound label A Established / approved	2.5 mg → increase by 2.5 mg every 4 wk to 5, 10 or 15 mg	Once weekly	Chronic	Subcutaneous

Clinical trials & studies

Phase 32022
Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1, NEJM)
2,539 adults; −20.9% at 15 mg vs −3.1% placebo.
Phase 32025
Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5, NEJM)
−20.2% vs −13.7% at 72 weeks.
LabelCurrent
Zepbound prescribing information
Official FDA label.

Safety

Side effects

Nausea, diarrhea, vomiting, constipation
Decreased appetite
Gallbladder events
Injection-site reactions

Contraindications

History of MTC or MEN2 (boxed warning)
Pregnancy
Serious hypersensitivity

Interactions

May reduce efficacy of oral contraceptives during initiation/escalation — label advises non-oral or backup method for 4 weeks
Insulin/sulfonylureas — hypoglycemia

Long-term safety

Multi-year data accumulating; SURMOUNT-OSA and cardiovascular outcome trials expand the safety record.

Regulatory status

FDA approved

FDA approved as Mounjaro (T2D) and Zepbound (obesity, OSA). EMA approved.

FAQ

Commonly discussed alongside

Semaglutide Retatrutide

Listing a combination does not mean it has been studied or is safe.

Considering a GLP-1 for weight loss?

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