Medical AISemaglutide vs tirzepatide - side by side.
A GLP-1 agonist and a dual GIP/GLP-1 agonist, both used in type 2 diabetes and obesity. Here is the efficacy, the safety signal, the dosing schedules, the contraindications, and where current guidelines place each, with the trials and labels they rest on.
Semaglutide and tirzepatide are the two most-discussed incretin therapies in type 2 diabetes and obesity. Semaglutide is a GLP-1 receptor agonist; tirzepatide is a dual agonist at both the GIP and GLP-1 receptors.[3] The two are sold under different brand names by indication: semaglutide as Ozempic for diabetes and Wegovy for weight management,[5,6] tirzepatide as Mounjaro for diabetes and Zepbound for weight management.[7,8]
The single head-to-head trial is SURPASS-2, which compared tirzepatide against semaglutide 1 mg in type 2 diabetes and found greater A1c and weight reduction with tirzepatide across its dose tiers.[3] Beyond that trial, most comparisons are cross-trial: STEP 1 studied semaglutide 2.4 mg in obesity,[1] SURMOUNT-1 studied tirzepatide in obesity,[2] and those populations and protocols differ. Read each result inside its own trial.
SURPASS-2 is the only direct comparison and favored tirzepatide on A1c and weight in type 2 diabetes.[3] Obesity efficacy figures come from separate trials and are not a head-to-head result.
Efficacy at a glance
Figures are drawn from each drug's own pivotal trial; the obesity columns are not a head-to-head comparison.
| Semaglutide | Tirzepatide | |
|---|---|---|
| Mechanism | GLP-1 receptor agonist | Dual GIP + GLP-1 receptor agonist |
| Obesity trial | STEP 1 (2.4 mg) | SURMOUNT-1 |
| Mean weight change, obesity trial | ~ -14.9% at 68 wk [1] | ~ -15% to -21% by dose at 72 wk [2] |
| Head-to-head (T2D) | Semaglutide 1 mg, comparator arm | Greater A1c and weight reduction (SURPASS-2) [3] |
| CV outcomes evidence | SUSTAIN-6: reduced MACE in high-risk T2D [4] | SURPASS-CVOT published in 2025 [10] |
Dosing
Both are once-weekly subcutaneous injections titrated slowly to limit gastrointestinal effects. Semaglutide for diabetes starts at 0.25 mg weekly (a non-therapeutic starter dose) and titrates over weeks; the weight-management formulation titrates to 2.4 mg weekly.[5,6] Tirzepatide starts at 2.5 mg weekly and titrates in 2.5 mg steps toward 5, 10, or 15 mg.[7,8] Confirm the exact titration schedule and maximum dose against the current label for the specific brand and indication.
Adverse-effect matrix
Relative frequency of common label-listed effects. Dots indicate a qualitative, label-informed gradient, not a quantitative head-to-head rate.
| Adverse effect | Semaglutide | Tirzepatide |
|---|---|---|
| Nausea | Common | Common |
| Vomiting / diarrhea | Common | Common |
| Pancreatitis (label warning) | Uncommon | Uncommon |
| Gallbladder disease | Uncommon | Uncommon |
| Thyroid C-cell tumors (boxed) | Boxed warning | Boxed warning |
Both labels carry a boxed warning for thyroid C-cell tumors based on rodent carcinogenicity data and list pancreatitis and gallbladder disease as warnings.[5,6,7,8] Gastrointestinal effects are the most common reason for discontinuation and are mitigated by slow titration.
Contraindications
Both are contraindicated in patients with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2, and in those with prior serious hypersensitivity to the drug.[5,6,7,8] Use caution with a history of pancreatitis and in severe gastrointestinal disease such as gastroparesis. Confirm pregnancy and lactation guidance on the current label.
Where guidelines place each
The American Diabetes Association Standards of Care suggest GLP-1 receptor agonists and the dual GIP/GLP-1 agonist among preferred options when weight management or cardiovascular and renal risk reduction is a priority, with agent choice individualized to the patient's comorbidities, tolerance, and access.[9] Tirzepatide now also has a completed cardiovascular outcomes trial in type 2 diabetes with established atherosclerotic cardiovascular disease.[10] Guideline framing evolves; read the current version alongside the cited trials.
One direct comparison favored tirzepatide on glycemia and weight in diabetes. Everything else is cross-trial and should be read as such.- Section synthesis
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