Zepbound and Mounjaro are both tirzepatide — the same active ingredient, same manufacturer (Eli Lilly), same injection pen. If you've been following GLP-1 medications, this probably sounds familiar. It's the same situation as Ozempic vs. Wegovy, just with a different drug.
FDA Approval: The Key Difference
Mounjaro was approved in 2022 for type 2 diabetes. Zepbound arrived in late 2023, approved specifically for chronic weight management in adults with obesity (BMI 30+) or overweight (BMI 27+) with at least one weight-related condition. (See our BMI calculator.)
Same molecule, different label. But that label matters a lot when it comes to getting your insurance to pay for it.
How Tirzepatide Works
Tirzepatide is a dual-action medication — it activates both GLP-1 and GIP receptors. This dual mechanism is what distinguishes it from semaglutide-based medications like Ozempic and Wegovy, which only target GLP-1 receptors. In clinical trials, tirzepatide produced average weight loss of about 20-22% of body weight at the highest dose, which edges out semaglutide's typical 15% range. (See our semaglutide guide.)
Both Zepbound and Mounjaro are available in doses from 2.5 mg up to 15 mg, administered weekly. The titration schedule is the same regardless of which brand name is on the box.
Cost and Insurance Coverage
Without insurance, both cost roughly $1,000-$1,200 per month. Eli Lilly runs savings programs for each, but the eligibility criteria differ based on the indication. (See our GLP-1 insurance coverage guide.) (See our savings calculator.)
Here's the practical reality: if you have type 2 diabetes, Mounjaro is more likely to be covered by your insurance. If obesity is your primary diagnosis, Zepbound is the appropriate prescription — but insurance coverage for weight loss medications is still inconsistent across plans.
Some doctors prescribe Mounjaro off-label for weight loss when Zepbound coverage is denied. This works pharmacologically (it's the same drug), but insurance companies can and do reject off-label claims. A clinic experienced with these medications will know how to work your specific insurance situation.
Side Effects
Since the active ingredient is identical, the side effect profile is the same for both. The most common issues are GI-related — nausea, diarrhea, constipation, and decreased appetite. These are generally worst in the first month and after dose increases. Most patients find them manageable, especially with the gradual dose escalation schedule.
Tirzepatide tends to have similar GI side effects to semaglutide, though some patients report tolerating one better than the other. There's no reliable way to predict this in advance.
Which Should You Ask For?
If you have diabetes, start the conversation with Mounjaro — the insurance path is clearer. If weight loss is your primary goal, Zepbound is what the FDA approved for that purpose. Your provider can help figure out which approach gives you the best shot at getting covered.
Either way, you're getting tirzepatide. The clinical outcomes don't depend on what's printed on the label.
Find Zepbound providers or search Mounjaro clinics in our directory. You can also compare tirzepatide to semaglutide options on our tirzepatide medication page.