Zepbound and Mounjaro contain the same active ingredient — tirzepatide — made by Eli Lilly. The difference is the FDA-approved indication: Mounjaro is approved for type 2 diabetes; Zepbound is approved for chronic weight management and obstructive sleep apnea in obesity. The dose strengths, titration schedule, side effects, and pharmacologic effects are identical. The choice between them depends primarily on your indication, insurance coverage, and whether you need cash-pay options.
Side-by-Side Comparison
| Feature | Zepbound | Mounjaro |
|---|---|---|
| Active ingredient | Tirzepatide | Tirzepatide |
| Manufacturer | Eli Lilly | Eli Lilly |
| Mechanism | GIP + GLP-1 dual agonist | GIP + GLP-1 dual agonist |
| FDA indication | Chronic weight management; OSA in obesity | Type 2 diabetes |
| Approval year | November 2023 | May 2022 |
| Dose range | 2.5 to 15 mg weekly | 2.5 to 15 mg weekly |
| Titration schedule | Monthly to 2.5, 5, 7.5, 10, 12.5, 15 mg | Monthly to 2.5, 5, 7.5, 10, 12.5, 15 mg |
| Frequency | Weekly SC injection | Weekly SC injection |
| Devices available | Single-dose pen + multi-dose vials (LillyDirect) | Single-dose pen only |
| List price/month (pen) | ~$1,060 | ~$1,070 |
| Cash price (vial via LillyDirect) | $349 to $699 | Not available |
| Pivotal trial program | SURMOUNT (1, 2, 3, 4, 5) | SURPASS (1, 2, 3, 4, 5) |
| CV outcomes trial | SURMOUNT-MMO (pending) | SURPASS-CVOT (pending) |
| Boxed warning | Thyroid C-cell tumors | Thyroid C-cell tumors |
What Each One Is
Mounjaro (tirzepatide) is a once-weekly subcutaneous injection FDA-approved in May 2022 for the treatment of type 2 diabetes in adults. It was studied in the SURPASS clinical trial program in patients with type 2 diabetes.
Zepbound (tirzepatide) is a once-weekly subcutaneous injection FDA-approved in November 2023 for chronic weight management in adults with obesity (BMI ≥ 30) or overweight (BMI ≥ 27) with at least one weight-related comorbidity. It was studied in the SURMOUNT clinical trial program in patients with overweight or obesity. In December 2024, Zepbound received an additional indication for obstructive sleep apnea in adults with obesity, based on the SURMOUNT-OSA trial. Read the tirzepatide overview.
Why the Same Drug Has Two Names
Eli Lilly markets tirzepatide under two brand names for several reasons:
- Insurance management — diabetes and weight-loss drugs are typically reviewed under different formularies, with different coverage rules; separate brand names make this easier to administer
- Marketing — different patient populations need different messaging
- Indication-specific labeling — packaging, prescribing information, and patient education differ by indication
- Pricing flexibility — separate brand names allow different pricing strategies and savings programs
Novo Nordisk does the same with semaglutide — Ozempic (T2D), Wegovy (obesity), and Rybelsus (oral T2D). See our comparison of Wegovy vs Ozempic.
Efficacy Across Indications
| Outcome | Mounjaro in T2D (SURPASS) | Zepbound in obesity (SURMOUNT) |
|---|---|---|
| A1C reduction (15 mg) | ~2.3 percentage points | ~1.8% in T2D subgroup; not primary outcome in obesity |
| Weight loss | ~11–12 kg / ~12% body weight | ~20% body weight in non-diabetic obesity |
| Apnea-hypopnea index reduction (OSA) | Not studied | ~50% reduction |
| Trial duration | 40–104 weeks | 72 weeks |
Notably, weight loss tends to be higher in obesity trials (SURMOUNT) than in diabetes trials (SURPASS), likely because patients with type 2 diabetes have less reserve weight to lose and physiologic differences in appetite regulation.
Insurance Coverage Differences
Insurance plans manage diabetes and weight-loss drug benefits separately. This is the main practical difference between Mounjaro and Zepbound for many patients:
- Mounjaro — generally covered under medical or pharmacy benefits for type 2 diabetes, often with prior authorization
- Zepbound — often excluded under weight-loss medication carveouts even when Mounjaro is covered by the same plan; the OSA indication is expanding coverage for some patients
- Medicare Part D covers Mounjaro for T2D; Medicare historically excludes weight-loss medications, though some plans now cover Zepbound for OSA
Cost and Cash-Pay Options
Pen list prices are nearly identical at approximately $1,060 to $1,070 per month. Both have Lilly manufacturer savings cards for commercially insured patients. The key cost difference is the LillyDirect cash-pay vial program for Zepbound:
| Dose | Zepbound vial (LillyDirect cash) | Mounjaro pen (list) |
|---|---|---|
| 2.5 mg | $349/month | ~$1,070/month |
| 5 mg | $499/month | ~$1,070/month |
| 7.5 mg | $599/month | ~$1,070/month |
| 10 mg | $699/month | ~$1,070/month |
For cash-pay patients without insurance, Zepbound vials are substantially cheaper than Mounjaro pens. The vials require drawing into a separate syringe and are slightly less convenient than the autoinjector pens, but the price difference can be meaningful.
Side Effects (Both — Identical)
- Nausea — most common, peaks during dose titration
- Vomiting, diarrhea, constipation
- Abdominal pain, dyspepsia
- Decreased appetite
- Fatigue
- Injection site reactions
- Gallbladder issues (cholelithiasis, cholecystitis)
- Pancreatitis (rare)
- Acute kidney injury (dehydration-driven)
- Hypoglycemia when combined with insulin or sulfonylureas
- Boxed warning for thyroid C-cell tumors — contraindicated with personal/family history of medullary thyroid carcinoma or MEN 2
When to Choose Mounjaro
- You have type 2 diabetes and need glucose control plus weight management — Mounjaro is the on-label option
- Insurance covers Mounjaro for diabetes but not Zepbound for weight loss
- You prefer the convenience of the autoinjector pen
- Medicare Part D coverage is needed (Zepbound coverage in Medicare remains limited)
When to Choose Zepbound
- You do not have diabetes but meet criteria for chronic weight management (BMI ≥ 30, or BMI ≥ 27 with comorbidity)
- You have obstructive sleep apnea in the context of obesity
- You are paying cash and want the lower-priced LillyDirect vial option
- Insurance covers Zepbound under your specific plan
Off-Label Crossover
Some patients with type 2 diabetes use Mounjaro for primary weight-loss benefit, given the substantial weight-loss effect at higher doses. This is on-label use because the FDA approval for type 2 diabetes does not specify glucose as the only treatment goal. Conversely, prescribing Mounjaro off-label for weight loss in patients without diabetes is increasingly discouraged by Lilly and not covered by most insurance plans — patients should use Zepbound for that indication.
Compounded Tirzepatide
During Mounjaro and Zepbound supply shortages (2022–2024), compounding pharmacies produced compounded tirzepatide formulations at lower prices. As of 2025, the FDA has declared the tirzepatide shortage resolved, and compounded tirzepatide is no longer permitted for routine use. Patients using compounded tirzepatide should transition to FDA-approved Mounjaro or Zepbound. Compounded versions are not FDA-evaluated for safety, purity, or potency.
Lifestyle Pairing
Both medications work best alongside diet and activity. Read about diet strategies and obesity-related complications.
The Bottom Line
Zepbound and Mounjaro are the same molecule (tirzepatide) under different brand names for different FDA-approved indications. Mounjaro is for type 2 diabetes; Zepbound is for chronic weight management and obstructive sleep apnea in obesity. The dose strengths, side effects, and pharmacologic effects are identical. Insurance coverage is often the practical determinant. For cash-pay patients without coverage, Zepbound vials through LillyDirect offer the most affordable access to tirzepatide. Talk to your doctor about which brand is on-label for your situation and what your insurance will cover.
