Mounjaro vs Zepbound: FDA Prescribing Information Explained Side-by-Side

Mounjaro® and Zepbound® are both Eli Lilly tirzepatide products at the exact same dose strengths (2.5 / 5 / 7.5 / 10 / 12.5 / 15 mg). They share an identical molecule and an almost-identical boxed warning. But the FDA approved them for different indications, they have different prescribing rules, and the Warnings & Precautions sections are ordered differently between the two labels — which matters when a clinician is checking the safety hierarchy. This is the verbatim side-by-side from the current DailyMed-hosted FDA labels, both revised 4/2026.

The thesis: same molecule, different labels, different rules

Tirzepatide is a single active ingredient — a dual GIP and GLP-1 receptor agonist. Eli Lilly sells it under two brand names because the FDA approved it through two separate New Drug Applications for two different indications:

• Mounjaro® was approved May 2022 for adults with type 2 diabetes mellitus. The label was extended in 2025 to include pediatric patients aged 10 and older.
• Zepbound® was approved November 2023 for chronic weight management. The label was extended in December 2024 to include moderate-to-severe obstructive sleep apnea (OSA) in adults with obesity.

The molecule is the same. The dose strengths are the same. The injection mechanism is the same. They are not interchangeable. They have separate NDC code families, separate prescribing rules, and (per the Zepbound label's Limitations of Use section, quoted below) co-administration with each other or with any other GLP-1 receptor agonist is not recommended.

Indications and Usage — Mounjaro vs Zepbound

Mounjaro (Section 1, verbatim from the FDA label)

MOUNJARO® is indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus.

That is the entire indication. Mounjaro is not FDA-approved for weight loss as a primary indication. It is approved for type 2 diabetes only. When clinicians prescribe Mounjaro for weight loss in patients without type 2 diabetes, that is an off-label use of the medication. (Off-label prescribing is legal in the US under physician judgment, but it is not the FDA-approved indication.)

Zepbound (Section 1, verbatim from the FDA label)

ZEPBOUND® is indicated in combination with a reduced-calorie diet and increased physical activity:

— to reduce excess body weight and maintain weight reduction long term in adults with obesity or adults with overweight in the presence of at least one weight-related comorbid condition.

— to treat moderate to severe obstructive sleep apnea (OSA) in adults with obesity.

Limitations of Use
ZEPBOUND contains tirzepatide. Coadministration with other tirzepatide-containing products or with any glucagon-like peptide-1 (GLP-1) receptor agonist is not recommended.

Zepbound is the FDA-approved channel for tirzepatide as a weight-loss medication. The OSA indication, added in December 2024, is the first and only FDA-approved pharmacologic treatment for obstructive sleep apnea — Zepbound is approved for OSA specifically in adults whose OSA is moderate-to-severe AND who have obesity (the trial population from SURMOUNT-OSA).

Dose escalation — the same staircase, almost the same words

Both labels use the same titration approach: start at 2.5 mg/week, increase to 5 mg after 4 weeks, then increase in 2.5 mg increments every 4 weeks until the maintenance dose. The rationale (reducing gastrointestinal side effects) is the same. The verbatim wording differs slightly because the indication framing differs.

Mounjaro (Section 2, verbatim)

— The recommended starting dosage of MOUNJARO is 2.5 mg injected subcutaneously once weekly.
— After 4 weeks, increase the dosage to 5 mg injected subcutaneously once weekly.
— If additional glycemic control is needed, increase the dosage in 2.5 mg increments after at least 4 weeks on the current dose. The maximum dosage of MOUNJARO is:
  — 15 mg injected subcutaneously once weekly in adults.
  — 10 mg injected subcutaneously once weekly in pediatric patients.

Zepbound (Section 2.1, verbatim)

— The recommended starting dosage of ZEPBOUND for all indications is 2.5 mg injected subcutaneously once weekly for 4 weeks.
— The 2.5 mg dosage is for treatment initiation and is not approved as a maintenance dosage.
— Follow the dosage escalation below for all indications to reduce the risk of gastrointestinal adverse reactions.
— After 4 weeks, increase the dosage to 5 mg injected subcutaneously once weekly. The dosage may be increased in 2.5 mg increments, after at least 4 weeks on the current dose.
— Consider treatment response and tolerability when selecting the maintenance dosage. If patients do not tolerate a maintenance dosage, consider a lower maintenance dosage.

Two practical differences worth noting:

• The Zepbound label is explicit that 2.5 mg is not a maintenance dose — it's a starter dose only. The Mounjaro label leaves room for staying at the maintenance dose that achieves glycemic control, which can in some patients be 5 mg or even 2.5 mg long-term in T2D.
• The Mounjaro pediatric maximum (10 mg) is lower than the adult maximum (15 mg). Zepbound is not currently approved for pediatric use.

The Boxed Warning — almost identical, one wording difference

Both labels carry the same boxed warning on thyroid C-cell tumors and medullary thyroid carcinoma (MTC). The trade names and one phrase about the rat species differ; the substance is identical.

Mounjaro (Boxed Warning, verbatim)

WARNING: RISK OF THYROID C-CELL TUMORS

— In both male and female rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. It is unknown whether MOUNJARO causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined.

— MOUNJARO is contraindicated in patients with a personal or family history of MTC or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Counsel patients regarding the potential risk for MTC with the use of MOUNJARO and inform them of symptoms of thyroid tumors (e.g., a mass in the neck, dysphagia, dyspnea, persistent hoarseness). Routine monitoring of serum calcitonin or using thyroid ultrasound is of uncertain value for early detection of MTC in patients treated with MOUNJARO.

Zepbound (Boxed Warning, verbatim)

WARNING: RISK OF THYROID C-CELL TUMORS

— In rats, tirzepatide causes dose-dependent and treatment-duration- dependent thyroid C-cell tumors at clinically relevant exposures. It is unknown whether ZEPBOUND causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined.

— ZEPBOUND is contraindicated in patients with a personal or family history of MTC or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Counsel patients regarding the potential risk for MTC with the use of ZEPBOUND and inform them of symptoms of thyroid tumors (e.g., a mass in the neck, dysphagia, dyspnea, persistent hoarseness). Routine monitoring of serum calcitonin or using thyroid ultrasound is of uncertain value for early detection of MTC in patients treated with ZEPBOUND.

The only substantive difference: the Mounjaro label says “In both male and female rats, tirzepatide causes…” while the Zepbound label says “In rats, tirzepatide causes….” The underlying nonclinical toxicology data is the same; the wording difference is editorial. For more on what the rodent thyroid signal does and does not mean for human risk, see our deep dive on GLP-1 medications and thyroid cancer evidence.

Contraindications — identical absolute exclusions

Both labels list two contraindications. The wording is virtually identical:

• Personal or family history of MTC, or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)
• Known serious hypersensitivity to tirzepatide or any excipient — both labels reference reports of anaphylaxis and angioedema

These are absolute contraindications: the FDA-approved labels say these patients should not take Mounjaro or Zepbound under any circumstances. They are not relative cautions.

Warnings & Precautions — same risks, different ordering

Both labels list 10 Warnings & Precautions subsections. The risks are largely identical, but the FDA chose to order them differently on the two labels — likely because the relative importance of each risk shifts between a glycemic-control population (Mounjaro) and a weight-management population (Zepbound).

Notable differences in the ordering:

• Severe gastrointestinal adverse reactions move from section 5.6 on Mounjaro to section 5.2 on Zepbound — i.e., GI risk is ranked higher on the weight-management label where most patients are starting from a non-diabetic baseline and may have less established gastric tolerance.
• Acute pancreatitis is 5.2 on Mounjaro but moves to 5.5 on Zepbound.
• Hypoglycemia on Mounjaro (5.3) is specifically about co-administration with insulin secretagogues or insulin — an important consideration in T2D management. Hypoglycemia on Zepbound (5.7) is a generic warning (less common because Zepbound patients aren't typically on insulin).
• Diabetic retinopathy on Zepbound (5.8) is restricted to patients with type 2 diabetes mellitus — recognizing that most Zepbound patients don't have diabetes, but a subset do.
• For Mounjaro and Zepbound, see also our deep dive on GLP-1 ileus and bowel obstruction and on anesthesia / ASA pre-procedure guidance.

Adverse reactions at the 15 mg dose — Zepbound has more reported AEs

Both labels publish placebo-controlled adverse-reaction tables for the highest dose (15 mg). The Zepbound table reports more frequent adverse reactions overall — partly because Zepbound was tested in a larger weight-management trial population (n=941 at 15 mg vs n=241 in the comparable Mounjaro placebo-controlled monotherapy analysis), and partly because the lower-baseline-GI-tolerance weight-management population reports more GI events.

Mounjaro 15 mg vs placebo (Section 6.1)

Placebo-controlled monotherapy table from the Mounjaro label.

Zepbound 15 mg vs placebo (Table 1, Section 6.1)

Adverse reactions ≥2% and greater than placebo in Zepbound-treated adults with obesity or overweight.

What this means in practice

• If a clinician prescribes Mounjaro for weight loss in a patient without type 2 diabetes, that is an off-label prescription. The FDA-approved label does not include a weight-management indication. This affects insurance coverage: most commercial plans only cover Mounjaro when type 2 diabetes is documented.
• Insurance and prior authorization diverges dramatically between the two products even though the molecule is identical. Mounjaro is reviewed against T2D criteria; Zepbound is reviewed against obesity criteria (which most plans now require BMI ≥30 with or without comorbidities). For more, see our insurance coverage landscape and the GLP-1 prior auth letter generator tool.
• Compounded tirzepatide is not Mounjaro and is not Zepbound. It is a separate preparation made by a licensed compounding pharmacy that contains the same active molecule. The FDA-approved labels above do not apply to compounded products. For the regulatory landscape, see compounded GLP-1 bioequivalence and our FDA warning letters database.
• The boxed warning applies to both products and to compounded tirzepatide. Personal or family history of MTC, or MEN 2 syndrome, is an absolute contraindication for any tirzepatide product regardless of brand.

Where to verify the labels yourself

We sourced both labels from DailyMed (NIH National Library of Medicine), which hosts the canonical FDA-approved Structured Product Labeling (SPL). DailyMed SetIDs are stable across label revisions, unlike accessdata.fda.gov PDF URLs which change silently.

• Mounjaro (tirzepatide) DailyMed page: dailymed.nlm.nih.gov/…/d2d7da5d
• Zepbound (tirzepatide) DailyMed page: dailymed.nlm.nih.gov/…/487cd7e7

Both labels were Revised: 4/2026 at the time we pulled this article on 2026-05-09. If you are reading this materially after that date, re-check the live DailyMed pages for any subsequent label revisions.