What they are
Semaglutide is a GLP-1 receptor agonist. It mimics glucagon-like peptide-1, a gut hormone released after eating that signals fullness, slows how quickly the stomach empties and helps regulate blood sugar. It is sold as Ozempic for type 2 diabetes and as Wegovy for chronic weight management.
Tirzepatide acts on two receptors: GLP-1 and GIP (glucose-dependent insulinotropic polypeptide), a second hormone involved in appetite and blood sugar. It is sold as Mounjaro for type 2 diabetes and as Zepbound for chronic weight management.
Side by side
| Semaglutide | Tirzepatide | |
|---|---|---|
| How it works | GLP-1 | GIP + GLP-1 |
| Weight-management brand | Wegovy (approved 2021) | Zepbound (approved 2023) |
| Dosing | Once-weekly injection, increased gradually | Once-weekly injection, increased gradually |
| Average loss in its main trial | About 15% of body weight over 68 weeks | About 15–21% over 72 weeks, depending on dose |
| Most common side effects | Nausea, diarrhea, constipation, vomiting | Similar |
Which one works better?
In the one large head-to-head trial so far (SURMOUNT-5, published in 2025), people taking tirzepatide lost more on average: about 20% of body weight, against about 14% on semaglutide, over 72 weeks.
That is a real difference, but it is an average. Some people do well on semaglutide, some tolerate one medication much better than the other, and cost, insurance coverage and supply often decide the question as much as the trial data does.
Side effects
Stomach and digestive effects are the most common with both: nausea, diarrhea, constipation, vomiting and reduced appetite. They tend to show up when the dose goes up and often ease after a few weeks, which is why both medications start low and increase slowly.
Less common but more serious risks include pancreatitis and gallbladder problems. Both medications carry a boxed warning about thyroid C-cell tumors seen in rodent studies, and neither is used by people with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2 (MEN 2). Neither is used during pregnancy.
What happens when you stop
Weight tends to come back. In the year after participants in the STEP 1 trial stopped semaglutide, they regained about two-thirds of the weight they had lost. That does not make the medication pointless. It means the plan has to cover the long term: either continuing treatment, or using the months on medication to build habits, protect muscle and taper under supervision.
How the decision gets made
Neither medication is right for everyone, and some people are better served by a plan without one. The choice comes from an evaluation: your health history, current medications, lab work and goals. Medication is one part of a plan that also covers nutrition, enough protein, strength training to protect muscle, and regular check-ins.
Talk it through with us
Every plan at Elite Medical Aesthetics starts with a consultation. Read more about Medical Weight Loss, or use the form below and we will call you back.
This article is general information, not medical advice. Whether a treatment is right for you depends on your own health history and an evaluation with a licensed provider.