Tirzepatide vs Semaglutide

Tirzepatide vs Semaglutide — at a glance

Mechanism of action

Tirzepatide activates both GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) receptors. Semaglutide activates only the GLP-1 receptor. The dual-agonist mechanism of tirzepatide is hypothesized to underlie its greater glycemic and weight-loss effects in head-to-head trials, though long-term cardiovascular outcome data are more mature for semaglutide (SUSTAIN-6, SELECT) than for tirzepatide (SURMOUNT-MMO ongoing as of 2026).

Efficacy at a glance

In SURPASS-2 (Frias et al., NEJM 2021), tirzepatide 5/10/15 mg produced HbA1c reductions of −2.01%/−2.24%/−2.30% vs −1.86% for semaglutide 1 mg over 40 weeks in adults with type 2 diabetes; weight loss was −7.6/−9.3/−11.2 kg for tirzepatide vs −5.7 kg for semaglutide. In obesity, SURMOUNT-1 reported mean weight loss of approximately 20.9% at tirzepatide 15 mg over 72 weeks vs roughly 14.9% at semaglutide 2.4 mg in STEP-1 — note these are separate trials, not head-to-head.

Side effects

Both drugs share GLP-1 class side effects: nausea (most common), vomiting, diarrhea, constipation, abdominal pain, injection-site reactions. Both carry a black-box warning for thyroid C-cell tumors based on rodent studies, contraindicated in personal/family history of medullary thyroid carcinoma (MTC) and Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Pancreatitis is a labeled risk for both.

Cost comparison

Brand-name tirzepatide (Mounjaro/Zepbound) lists at approximately $1,000–$1,200/month before insurance; Lilly's LillyDirect program offers reduced cash-pay pricing on single-dose vials. Brand-name semaglutide (Ozempic/Wegovy) lists similarly. Compounded tirzepatide via telehealth ranges from $186/month (NexLife 12-month plan) to roughly $499/month; compounded semaglutide has a similar telehealth price range. Compounded versions are not FDA-approved and are not the same as the brand products.

Who chooses which

Patients with type 2 diabetes have FDA-approved options in both classes (Mounjaro for tirzepatide; Ozempic and Rybelsus for semaglutide). For weight management without diabetes, Zepbound (tirzepatide) and Wegovy (semaglutide) are both FDA-approved; tirzepatide produced numerically greater weight loss in separate Phase 3 trials but has shorter post-marketing experience. Discuss your specific clinical context with a licensed clinician.

Frequently asked

Is tirzepatide better than semaglutide?
In the SURPASS-2 head-to-head trial, tirzepatide produced greater HbA1c reduction and weight loss than semaglutide 1 mg in adults with type 2 diabetes over 40 weeks. For obesity, no direct head-to-head trial has compared tirzepatide 15 mg with semaglutide 2.4 mg as of 2026; separate Phase 3 trials show numerically greater weight loss with tirzepatide. 'Better' depends on clinical context, side-effect tolerance, and access.

Can you switch from semaglutide to tirzepatide?
Yes, with clinician supervision. Most clinicians restart titration from 2.5 mg tirzepatide weekly after a washout period of one to two weeks from the last semaglutide dose, then titrate every 4 weeks as tolerated. Switching is common; the clinical evidence for direct transition protocols is observational.

Are tirzepatide and semaglutide in the same class?
Both are incretin-based therapies, but they are not in the same drug class strictly speaking. Semaglutide is a GLP-1 receptor agonist (single agonist). Tirzepatide is a dual GLP-1 / GIP receptor agonist. The dual-agonist class is sometimes called 'twincretins.'