Medications · 5 min read
Zepbound vs. Wegovy: how the two weekly injections compare
Both are once-weekly pens. One acts on two hormones, the other on one. Here's what a head-to-head trial found.
Zepbound and Wegovy are both once-weekly injections approved for chronic weight management in adults. They're often mentioned together, but they work a little differently, and that difference showed up when the two were tested head to head.
One hormone or two
Wegovy contains semaglutide, which mimics GLP-1, a gut hormone that slows digestion and signals fullness. Zepbound contains tirzepatide, which acts on GLP-1 and a second hormone, GIP. Both reduce appetite; tirzepatide's dual action is the main reason researchers expected it to produce more weight loss.
What the head-to-head trial found
In SURMOUNT-5, adults with obesity and no diabetes took either tirzepatide or semaglutide at the highest tolerated dose for 72 weeks. Average weight change was −20.2% with tirzepatide and −13.7% with semaglutide.1 Lilly reported that 64.6% of people on Zepbound lost at least 15% of their body weight, compared with 40.1% on Wegovy.2
| Zepbound | Wegovy | |
|---|---|---|
| Medicine | tirzepatide | semaglutide |
| Acts on | GIP and GLP-1 | GLP-1 |
| Average loss, SURMOUNT-5 | 20.2% at 72 weeks | 13.7% at 72 weeks |
| Other approved uses | Moderate to severe obstructive sleep apnea with obesity | Reducing cardiovascular risk in adults with heart disease and excess weight |
| Self-pay | From $299/mo at 2.5 mg through LillyDirect3 | Through NovoCare; confirmed at your visit |
More weight loss isn't the only factor
Side effects are similar: mostly nausea, diarrhea, constipation and vomiting, especially while the dose is rising. Wegovy has a proven benefit for heart attack and stroke risk in people with established heart disease, which can matter more than a few extra points of weight loss. Cost, coverage and how your body responds all play a part too.
Your clinician weighs your health history, goals and budget before recommending either one. Neither is right for people with a personal or family history of medullary thyroid cancer or MEN 2.
