Comparison

Tirzepatide vs Retatrutide

Dual agonist versus triple agonist: how the current standard compares to the next generation.

Tirzepatide

Established

Brand names: Mounjaro, Zepbound

Dual GIP/GLP-1 receptor agonist producing greater average weight loss than semaglutide in head-to-head trials.

Full Tirzepatide profile

Retatrutide

Clinical

Investigational triple agonist (GLP-1, GIP, glucagon) producing the largest weight loss seen in Phase II trials to date.

Full Retatrutide profile

Attribute	Tirzepatide	Retatrutide
Category	Incretin / GLP-1 Compounds	Incretin / GLP-1 Compounds
Evidence tier	Established	Clinical
FDA status	FDA-approved (T2D and chronic weight management).	Investigational. Not approved. Compounding is not legally available.
Mechanism	Tirzepatide activates both GIP and GLP-1 receptors. The GIP component appears to modulate adipose tissue and improve insulin sensitivity, while GLP-1 action drives appetite suppression and glycemic control. Half-life ~5 days enables weekly dosing.	Retatrutide activates GLP-1, GIP, and glucagon receptors. The glucagon agonism is hypothesized to increase energy expenditure through hepatic and adipose effects, while the GLP-1/GIP arms drive appetite suppression.
Key benefits	Up to 22.5% body weight reduction at 15 mg (SURMOUNT-1) Superior HbA1c lowering vs. semaglutide (SURPASS-2) Improvements in sleep apnea severity (SURMOUNT-OSA) Favorable lipid profile changes	24% mean body weight reduction at 48 weeks (Phase II, 12 mg) Improvements in hepatic fat and liver enzymes Potential energy expenditure effect via glucagon arm
Dosage range	2.5 – 15 mg weekly	1 – 12 mg weekly (trial protocol)
Frequency	Weekly	Weekly
Route	SubQ	SubQ
Common side effects	Nausea, diarrhea, constipation, Injection site reactions, Hypoglycemia when combined with insulin or sulfonylureas	Nausea, GI effects similar to other incretins, Transient heart rate increase, Limited long-term safety data

Educational reference only, not medical advice. Data reflects each compound’s profile page; see individual profiles for references and full safety information.

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