What Active Ingredients Do Zepbound and Wegovy Use?
Zepbound contains tirzepatide, a dual GLP-1 and GIP receptor agonist that mimics two gut hormones to boost insulin release, slow digestion, and reduce appetite. Wegovy uses semaglutide, a GLP-1 receptor agonist only, targeting one hormone for similar effects on blood sugar and hunger but without GIP action.[1][2]
Which Is Approved for What Uses?
Zepbound is FDA-approved for chronic weight management in adults with obesity (BMI ≥30) or overweight (BMI ≥27) with weight-related conditions like hypertension or type 2 diabetes. Wegovy is approved for the same weight management group, plus chronic weight management in kids aged 12+ with obesity. Neither is approved as a diabetes drug—those are Mounjaro (tirzepatide) and Ozempic/Wegovy lower-dose versions (semaglutide).[1][3]
How Do Their Weight Loss Results Compare?
In trials, Zepbound users lost 15-21% of body weight over 72 weeks (20-52 mg doses), outperforming Wegovy's 15% average loss at its 2.4 mg dose over 68 weeks. Tirzepatide's dual mechanism often drives slightly better results, especially in head-to-head studies, though individual responses vary.[2][4]
What Dosing Schedules and Forms Exist?
Both are weekly subcutaneous injections via pre-filled pens:
- Zepbound: Starts at 2.5 mg, titrates to 5, 10, or 15 mg.
- Wegovy: Starts at 0.25 mg, titrates to 2.4 mg.
Pens differ in design and needle size; Zepbound offers single-dose vials for pharmacies, unlike Wegovy's branded pens only.[1][3]
Who Makes Them and What Do They Cost?
Eli Lilly manufactures Zepbound (U.S. list price ~$1,060/month). Novo Nordisk makes Wegovy (~$1,350/month). Insurance coverage varies; both face shortages, with patient assistance programs available. Prices exclude copays or discounts.[5]
Common Side Effects and Safety Profile
Both cause nausea, diarrhea, vomiting, and constipation, mostly during dose ramps—Zepbound's rates are similar or slightly higher due to dual action. Rare risks include pancreatitis, gallbladder issues, or thyroid tumors (boxed warning for semaglutide). No head-to-head safety data shows major differences.[1][2]
Can You Switch Between Them?
Switching is possible under doctor guidance due to different ingredients and titration, but no direct conversion exists—restart at low doses to minimize GI side effects. They're not interchangeable for efficacy.[4]
Sources:
[1] https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/tirzepatide-marketed-zepbound-information
[2] https://www.nejm.org/doi/full/10.1056/NEJMoa2206038 (SURMOUNT-1 trial)
[3] https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/semaglutide-injection-marketed-wegovy-information
[4] https://www.nejm.org/doi/full/10.1056/NEJMoa2032183 (STEP trials)
[5] https://www.drugs.com/price-guide/zepbound