Tirzepatide

Mounjaro, Zepbound

Grade A: Approved and proven

TL;DR: Tirzepatide is approved by the FDA for type 2 diabetes (Mounjaro) and chronic weight management (Zepbound), supported by an extensive phase 3 trial program. The SURPASS series of trials in type 2 diabetes demonstrated substantial reductions in HbA1c and body weight, with tirzepatide outperforming comparator GLP-1 agents in several head-to-head studies. The SURMOUNT trials in obesity without diabetes showed large and sustained weight loss, with tirzepatide demonstrating numerically greater average weight reduction than semaglutide in direct comparative analyses. The SURPASS-CVOT trial, comparing tirzepatide to dulaglutide in over 13,000 patients with type 2 diabetes and established cardiovascular disease over a median of approximately four years, showed tirzepatide was non-inferior to dulaglutide for major adverse cardiovascular events; dedicated superiority versus placebo has not been established as of mid-2026. Evidence is grade A given multiple large RCTs and two FDA approvals, though cardiovascular outcomes superiority data remain pending.

Key Takeaways

Grade A: Approved and proven
FDA approved: Approved as Mounjaro (subcutaneous injection, type 2 diabetes) and Zepbound (subcutaneous injection, chronic weight management and, additionally, obstructive sleep apnea in adults with obesity).
Compounding: FDA-approved; brand name only (no generic as of mid-2026). Mass compounding from bulk API was permitted during a declared shortage that FDA resolved in December 2024; enforcement grace periods for 503A and 503B compounders ended by March 2025. Mass compounding of tirzepatide is now prohibited. FDA proposed in April 2026 to formally exclude tirzepatide from the 503B Bulks List. Narrow 503A exceptions for documented patient-specific clinical need may apply.

Tirzepatide chemical structure — Structure via PubChem CID 166567236

Mechanism

Tirzepatide is a dual GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 receptor agonist, which stimulates insulin secretion, suppresses glucagon, reduces appetite, and slows gastric emptying through activation of both receptor pathways.

Evidence

Tirzepatide is approved by the FDA for type 2 diabetes (Mounjaro) and chronic weight management (Zepbound), supported by an extensive phase 3 trial program. The SURPASS series of trials in type 2 diabetes demonstrated substantial reductions in HbA1c and body weight, with tirzepatide outperforming comparator GLP-1 agents in several head-to-head studies. The SURMOUNT trials in obesity without diabetes showed large and sustained weight loss, with tirzepatide demonstrating numerically greater average weight reduction than semaglutide in direct comparative analyses. The SURPASS-CVOT trial, comparing tirzepatide to dulaglutide in over 13,000 patients with type 2 diabetes and established cardiovascular disease over a median of approximately four years, showed tirzepatide was non-inferior to dulaglutide for major adverse cardiovascular events; dedicated superiority versus placebo has not been established as of mid-2026. Evidence is grade A given multiple large RCTs and two FDA approvals, though cardiovascular outcomes superiority data remain pending.

Safety and risks

Boxed warning: tirzepatide causes thyroid C-cell tumors in rats at clinically relevant exposures; human relevance is unknown and the drug is contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Patients should report neck masses, hoarseness, or difficulty swallowing. Acute pancreatitis, including fatal or non-fatal hemorrhagic or necrotizing forms, has been reported; discontinue if suspected and do not restart if confirmed. Acute gallbladder disease including cholelithiasis and cholecystitis has been observed in clinical trials at higher rates than placebo. Serious hypersensitivity reactions including anaphylaxis and angioedema have been reported and represent a labeled contraindication for patients with known prior serious hypersensitivity to tirzepatide. Hypoglycemia risk is elevated when used with insulin or sulfonylureas; in trials with concomitant diabetes agents, hypoglycemia occurred meaningfully more often than with placebo. Mean resting heart rate increases of 1 to 3 beats per minute have been observed. The most common adverse effects are nausea, diarrhea, vomiting, constipation, and abdominal pain.

Interactions

Increased hypoglycemia risk when co-administered with insulin or insulin secretagogues; dose reduction of those agents should be considered. Slowed gastric emptying may reduce the rate of absorption of orally administered medications.

Federal compounding status

FDA-approved drug as of 2026-06-02.

An FDA-approved drug that should be obtained as the licensed product. It is not a 503A bulk-substance candidate; compounding from bulk is limited under federal rules and generally permitted only during a declared shortage.

Federal status only, from public FDA records. State pharmacy-board rules vary and are not covered here. This is regulatory reporting, not legal advice. All compounds.

Compounding legality

FDA-approved; brand name only (no generic as of mid-2026). Mass compounding from bulk API was permitted during a declared shortage that FDA resolved in December 2024; enforcement grace periods for 503A and 503B compounders ended by March 2025. Mass compounding of tirzepatide is now prohibited. FDA proposed in April 2026 to formally exclude tirzepatide from the 503B Bulks List. Narrow 503A exceptions for documented patient-specific clinical need may apply.

Sources

Tirzepatide is FDA approved. PeptideGrids presents evidence and regulatory status for informational purposes only. We do not sell, supply, source, or help anyone obtain this compound, and we provide no dosing or administration guidance. This is not medical advice; consult a licensed clinician. Full disclaimer.

Last reviewed June 1, 2026 by PeptideGrids editorial team (independently audited).