Semaglutide vs. tirzepatide
Updated August 2026 · The two most-discussed weight-management medications, compared honestly: mechanisms, what trials suggest, side effects, and how a clinician actually chooses.
The short answer
Wegovy (semaglutide) and Zepbound (tirzepatide) are both FDA-approved for chronic weight management in eligible adults. In published trials, average weight loss has been greater with tirzepatide — but averages are not individual predictions, both medicines produce meaningful results for many patients, and side effects, coverage, availability, and cost often decide the question in practice. The choice is made with a prescribing clinician after reviewing your history, not from a leaderboard.
How they work
Semaglutide activates the GLP-1 receptor; tirzepatide activates both the GLP-1 and GIP receptors. Both reduce appetite and slow stomach emptying, which supports eating less without white-knuckle willpower. The dual mechanism is one reason average trial results have differed. Both are weekly self-administered injections with doses escalated gradually to improve tolerance.
What the trials suggest
Across their pivotal trials — and in a head-to-head comparison — average weight loss has been greater with tirzepatide than semaglutide. Individual results vary by the specific product, dose, treatment duration, health status, side effects, access, and adherence. We review the evidence for the product being considered and set an individualized health goal; no amount of weight loss is guaranteed, and follow-up looks at more than scale weight.
Names that cause confusion
Ozempic and Mounjaro contain the same molecules (semaglutide and tirzepatide, respectively) but are FDA-approved for type 2 diabetes; Wegovy and Zepbound are the weight-management approvals. Compounded versions of semaglutide or tirzepatide are not FDA-approved and are not generic equivalents of approved branded products — a distinction we walk through before any prescription decision.
Side effects and who should not take them
Gastrointestinal effects are the most common for both, especially during dose escalation. Risks and contraindications vary by product and can include pancreatitis, gallbladder disease, kidney injury from dehydration, hypoglycemia with some diabetes medicines, and hypersensitivity reactions. Certain products are contraindicated with a personal or family history of medullary thyroid carcinoma or MEN2 and should not be used during pregnancy. Your history and the current prescribing information are reviewed before either medicine is considered.
How long treatment lasts
Obesity is a chronic disease, and medicines approved for chronic weight management may be continued long term while they remain beneficial, tolerated, accessible, and appropriate. Weight regain is common after stopping. Duration — and any decision to stop or switch — is made with the prescribing clinician, not on your own.
Frequently asked questions
Which works better, semaglutide or tirzepatide?
In published clinical trials, average weight loss has been greater with tirzepatide than with semaglutide, including in a head-to-head trial. Averages are not individual predictions: results vary by dose, treatment duration, health status, side effects, access, and adherence, and no amount of weight loss is guaranteed. Which medicine is appropriate for you — if either — is decided with the prescribing clinician.
What is the difference between how they work?
Semaglutide activates the GLP-1 receptor. Tirzepatide activates both the GLP-1 and GIP receptors. Both reduce appetite and slow stomach emptying, which supports eating less; the dual mechanism is one reason average results have differed in trials.
Are Wegovy and Zepbound the same as Ozempic and Mounjaro?
Same molecules, different FDA-approved uses: Wegovy (semaglutide) and Zepbound (tirzepatide) are approved for chronic weight management, while Ozempic and Mounjaro carry the same active ingredients approved for type 2 diabetes. Compounded versions of semaglutide or tirzepatide are not FDA-approved and are not generic equivalents of approved branded products.
Which has worse side effects?
Both are commonly associated with gastrointestinal effects, especially during dose escalation. Risks and contraindications vary by product and can include pancreatitis, gallbladder disease, kidney injury from dehydration, hypoglycemia with some diabetes medicines, and hypersensitivity reactions; certain products are contraindicated with a personal or family history of medullary thyroid carcinoma or MEN2 and should not be used during pregnancy. Your history and the current prescribing information must be reviewed before either is prescribed.
How is the choice made between them?
The product name, FDA approval status, expected benefits, material risks, and estimated cost are discussed before any prescription decision. Practical factors matter too: insurance coverage and pharmacy availability differ by product and change over time. At Ignite HRT medication is not included in the membership and is priced separately by the pharmacy, so the estimated cost of the specific product is part of the conversation up front.
Talk it through in person
Ignite HRT's medical weight-management program serves the Portland metro from Gresham and Beaverton, Oregon: a $215 new-patient visit, then $109/month membership if you enroll, with medication priced separately and every cost confirmed before enrollment. Book a free 15-minute informational call to ask which option fits your situation.
This guide is educational and is not a substitute for professional medical advice, diagnosis, or treatment. Medication choice, dose, and duration are individual clinical decisions made with your prescriber.