Zepbound® vs. Wegovy®:what is the difference?

Zepbound® (tirzepatide) and Wegovy® (semaglutide) are both FDA-approved, once-weekly medications for chronic weight management. They work in similar ways, but not identical ones, and that difference shows up in results, side effects, and how your physician decides between them.

One hormone or two

Wegovy contains semaglutide, which activates the GLP-1 receptor. GLP-1 is a gut hormone that tells your brain you are full and slows how quickly food leaves your stomach.

Zepbound contains tirzepatide, the first medication that activates both the GLP-1 and GIP receptors. GIP is a second gut hormone involved in appetite and how your body processes sugar and fat. Acting on both pathways is thought to explain why tirzepatide has produced larger average weight loss in studies.

What the research shows

In their large placebo-controlled trials, adults taking the highest dose of Wegovy lost about 15% of their body weight on average over roughly 68 weeks. Adults taking the highest dose of Zepbound lost about 21% on average over 72 weeks.

The two have also been compared directly. In a head-to-head trial in adults with obesity, people on tirzepatide lost about 20% of their body weight on average, versus about 14% on semaglutide.

Averages are not destiny. Many people do very well on semaglutide, and some people do not tolerate the higher doses of either medication. That is why the choice is individual.

Forms and dosing

Both are started at a low dose and increased about every four weeks to help your body adjust. Zepbound is available as a weekly KwikPen® or a weekly single-dose vial through LillyDirect. Wegovy is available as a weekly auto-injector pen or, for patients who prefer not to inject, as a once-daily Wegovy® pill through NovoCare.

Side effects

Side effects are similar for both: nausea, diarrhea, constipation, vomiting, and stomach discomfort are the most common, especially when starting or increasing a dose. They usually ease over time. Both carry the same boxed warning about thyroid C-cell tumors and should not be used by people with a personal or family history of medullary thyroid carcinoma or MEN 2. Read the Important Safety Information.

Cost

Through the manufacturer programs, Zepbound starts at $299 per month and the Wegovy pen at $349 per month; the Wegovy pill starts at $149. Prices are set by Eli Lilly and Novo Nordisk and change often. Your Cabot Medical membership ($78 for the first month, $118 after) is separate. See current pricing.

How your physician chooses

At Cabot Medical, a board-certified physician reviews your health history, goals, prior experience with medications, and whether you prefer an injection or a pill. Availability matters too: the Zepbound vial is often easier to get when pens are on backorder. Either way, you will only ever be prescribed an FDA-approved medication, never a compounded alternative.

This article is for general education and is not medical advice. Talk with a licensed physician about your individual situation.