Is Zepbound the Same as Mounjaro? Understanding the Identical Ingredient with Different Purposes

October 5, 2025 •

4 min read

Zepbound and Mounjaro are molecularly identical drugs produced by the same manufacturer, with the key difference being their distinct FDA-approved indications. While both contain the active ingredient tirzepatide, Mounjaro treats Type 2 diabetes and Zepbound is approved for chronic weight management and obstructive sleep apnea.

Quick Summary

Zepbound and Mounjaro contain the identical active ingredient, tirzepatide, and are manufactured by Eli Lilly. The crucial distinction lies in their FDA approval: Mounjaro is for Type 2 diabetes, while Zepbound treats chronic weight management and sleep apnea. This difference dictates their prescribing purpose and insurance coverage.

Key Points

Same Active Ingredient: Zepbound and Mounjaro contain the identical active ingredient, tirzepatide.
Different FDA Approvals: Mounjaro is approved for Type 2 diabetes, while Zepbound is approved for chronic weight management and obstructive sleep apnea.
Identical Mechanism of Action: Both drugs work as dual GIP and GLP-1 receptor agonists to regulate blood sugar and appetite.
Distinct Insurance Coverage: Coverage typically depends on the specific FDA-approved use, meaning a diabetes diagnosis is needed for Mounjaro coverage and an obesity/OSA diagnosis is needed for Zepbound coverage.
Shared Side Effect Profile: Because they are the same drug, their side effects, primarily gastrointestinal, are similar.
No Interchangeability: Patients should not use both medications simultaneously, as this would lead to an overdose of the same active ingredient.

Identical Ingredients, Different Indications

At a molecular level, the core of the matter is that Zepbound and Mounjaro are identical medications. Both brand names are for the same active ingredient, tirzepatide. The development of tirzepatide by Eli Lilly initially focused on treating Type 2 diabetes. However, clinical trials revealed that participants also experienced significant weight loss, leading the manufacturer to seek separate FDA approvals for different indications.

This deliberate strategy of dual branding is driven by regulatory requirements and market segmentation. It allows healthcare providers to prescribe the medication for its specific FDA-approved purpose, which in turn influences insurance coverage and cost for patients. The drug itself, its chemical structure, and its mechanism of action are exactly the same regardless of whether the packaging says Mounjaro or Zepbound.

The Mechanism Behind Tirzepatide

Tirzepatide is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. This means it mimics the action of two natural gut hormones, GIP and GLP-1, to produce several powerful effects on the body:

Enhances Insulin Release: Tirzepatide stimulates the pancreas to produce more insulin after you eat, helping to lower blood sugar levels.
Reduces Sugar Production: It decreases the amount of sugar the liver produces, further helping to regulate blood sugar levels.
Slows Gastric Emptying: By delaying how quickly food leaves the stomach, it promotes a feeling of fullness for longer periods.
Regulates Appetite: It acts on appetite centers in the brain to reduce hunger and cravings, leading to decreased calorie intake.

This combined action explains why tirzepatide is effective for both managing blood sugar in diabetes and promoting weight loss. Mounjaro leverages these effects primarily for glucose control, while Zepbound uses them for chronic weight management.

Mounjaro: Focusing on Type 2 Diabetes

Mounjaro was the first of the two brand names to receive FDA approval in May 2022, for improving blood sugar control in adults with Type 2 diabetes. It is prescribed in conjunction with diet and exercise. The dosage, which comes in pre-filled pens for a once-weekly subcutaneous injection, ranges from 2.5 mg up to 15 mg. For commercially insured patients, Eli Lilly often offers savings programs to reduce out-of-pocket costs when the medication is used for its approved indication.

While Mounjaro's off-label use for weight loss became widespread due to its effectiveness in clinical trials, insurance providers typically only cover it for Type 2 diabetes. This creates a significant cost difference for patients, as the retail price without insurance can exceed $1,000 per month.

Zepbound: The Weight Management Solution

Following Mounjaro's approval, Zepbound received FDA approval in November 2023 for chronic weight management in adults with obesity or overweight with at least one weight-related condition. In December 2024, Zepbound gained an additional FDA approval for treating moderate-to-severe obstructive sleep apnea (OSA) in adults with obesity. Like Mounjaro, it is a once-weekly subcutaneous injection available in the same dose strengths.

The approval for Zepbound directly addresses the medical need for obesity and OSA treatment. Insurance coverage for weight-loss medication varies significantly by plan and state, and patients may still face high costs. However, Eli Lilly also offers savings programs for commercially insured patients for Zepbound, and direct cash-pay options are available.

A Side-by-Side Comparison: Zepbound vs. Mounjaro


Feature	Mounjaro	Zepbound
Active Ingredient	Tirzepatide	Tirzepatide
FDA-Approved Use	Type 2 Diabetes in adults	Chronic Weight Management in adults with obesity/overweight + comorbidity, and Obstructive Sleep Apnea (OSA)
Manufacturer	Eli Lilly and Company	Eli Lilly and Company
Administration	Once-weekly subcutaneous injection	Once-weekly subcutaneous injection
Dosage Strengths	2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg	2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg
Common Side Effects	Nausea, diarrhea, vomiting, constipation	Nausea, diarrhea, vomiting, constipation
Insurance Coverage	Coverage is common for Type 2 diabetes indication	Coverage varies greatly and may be less common; depends on plan

Practical Considerations for Patients and Prescribers

For patients, the choice between Mounjaro and Zepbound is not about which medication is more effective, but rather which one is clinically appropriate and covered by their insurance. Using Mounjaro off-label for weight loss might result in a denial of coverage, leading to significant out-of-pocket expenses. Conversely, using Zepbound for diabetes would be considered off-label and face similar coverage hurdles.

It is crucial for patients and their healthcare providers to discuss the primary condition being treated. This ensures the correct prescription is issued, maximizing the chances of insurance coverage. Additionally, because the active ingredient is the same, patients should never use both medications at the same time, as this would lead to a double dose and increased risk of side effects.

Common Side Effects and Management

Due to their identical active ingredient, Zepbound and Mounjaro share a similar side effect profile. Most side effects are gastrointestinal and tend to be most prominent when starting the medication or increasing the dose. They often improve over time as the body adjusts. Common side effects include:

Nausea
Diarrhea
Vomiting
Constipation
Stomach pain
Decreased appetite

Management strategies often involve eating smaller, more frequent meals, staying hydrated, and avoiding greasy or heavy foods. Patients should always consult their healthcare provider about managing side effects or any persistent symptoms.

Conclusion

In summary, Zepbound is the same as Mounjaro in all but one crucial aspect: its FDA-approved indication. Both medications use the potent dual GIP/GLP-1 agonist tirzepatide to regulate blood sugar and appetite. Mounjaro is approved for Type 2 diabetes, while Zepbound is approved for chronic weight management and sleep apnea. This distinction, rather than the drug's composition, dictates which brand is prescribed and whether insurance will cover the cost. Patients should consult their doctor to determine the correct medication based on their medical condition and insurance coverage, ensuring they do not use both products simultaneously. For more information on Zepbound's FDA approval for obstructive sleep apnea, see the FDA's press release.

Frequently Asked Questions

A person with Type 2 diabetes should consult their doctor about the appropriate prescription. Since Mounjaro is specifically approved for Type 2 diabetes, and Zepbound for weight management, the correct prescription depends on the patient's primary treatment goal and insurance coverage. It is generally recommended to use the medication approved for the specific condition you are treating.

They are marketed separately to comply with FDA labeling requirements for different indications, allowing the manufacturer to target specific patient populations and to align with insurance coverage pathways. This dual-branding strategy is common when a drug has multiple approved uses.

Yes, both Mounjaro and Zepbound are available in the same six dosage strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg, administered as a once-weekly subcutaneous injection.

No, you should never use Mounjaro and Zepbound together. Since they contain the same active ingredient (tirzepatide), using both would result in a double dose, which could lead to serious side effects.

The retail list prices are very similar, often exceeding $1,000 per month without insurance. However, the out-of-pocket cost for a patient is heavily dependent on their insurance plan. Coverage is often tied to the medication’s specific FDA-approved indication.

The most common side effects are identical due to the shared active ingredient and include gastrointestinal issues such as nausea, diarrhea, vomiting, constipation, and stomach pain.

Your insurance is unlikely to cover Mounjaro for weight loss, as that would be an off-label use not included in its FDA approval. You would likely need to pay the full retail price if you were to receive an off-label Mounjaro prescription.