Mounjaro and Zepbound are both tirzepatide, which their FDA labels describe as a GIP receptor and GLP-1 receptor agonist.
Mounjaro is approved, with diet and exercise, to improve blood sugar control in adults and children 10 years and older with type 2 diabetes, and to reduce the risk of major adverse cardiovascular events in adults with type 2 diabetes who are at high risk for them.
Zepbound is approved, with a reduced-calorie diet and more physical activity, to reduce excess body weight and keep it off long term in adults with obesity, or with overweight and at least one weight-related condition, and to treat moderate to severe obstructive sleep apnea in adults with obesity.
Both labels set the same dose escalation in section 2, which starts at 2.5 mg once weekly.