⚠️ Important Safety Information
Boxed Warning: Thyroid C-cell tumors have been observed in animal studies. Mounjaro is contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Consult your healthcare provider about your risk.
What is Mounjaro?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist. It activates the receptors for two gut hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), which help regulate blood sugar and appetite (Mounjaro Prescribing Information, section 12.1). It is FDA-approved for two indications:
1. Type 2 Diabetes: To improve blood sugar control in adults and children 10 years and older with type 2 diabetes, in combination with diet and exercise (Mounjaro Prescribing Information, section 1).
2. Cardiovascular Risk Reduction: To reduce the risk of major adverse cardiovascular events (heart attack, stroke, cardiovascular death) in adults with type 2 diabetes and established cardiovascular disease. The FDA approved this indication in August 2026 based on the SURPASS-CVOT trial (Mounjaro Prescribing Information, revised August 2026).
Not FDA-approved for weight loss. Zepbound (same active ingredient, tirzepatide) is the FDA-approved brand for chronic weight management (Zepbound Prescribing Information).
How does Mounjaro compare to other GLP-1 medications?
| Medication | Active Ingredient | Frequency | Average A1C Reduction | Average Weight Loss |
|---|---|---|---|---|
| Mounjaro | Tirzepatide | Once weekly | 1.8-2.1% (5 mg dose) | 12-17 lbs |
| Mounjaro | Tirzepatide | Once weekly | 1.7-2.4% (15 mg dose) | 17-25 lbs |
| Trulicity | Dulaglutide | Once weekly | 1.0-1.5% | 4-8 lbs |
| Victoza | Liraglutide | Daily | 1.0-1.5% | 6-10 lbs |
Data from respective FDA labels and head-to-head clinical trials. Mounjaro ranges are average changes at 40-52 weeks in SURPASS-1 to -5 (Mounjaro Prescribing Information, section 14). Individual results vary.
How does Mounjaro work?
Tirzepatide is a dual GIP and GLP-1 receptor agonist. It binds to and activates both the GIP and GLP-1 receptors (Mounjaro Prescribing Information, section 12). It works through three primary mechanisms:
1. Increases insulin secretion: Stimulates the pancreas to release insulin in response to elevated blood sugar (glucose-dependent, so lower risk of hypoglycemia when used alone).
2. Decreases glucagon levels: Reduces fasting and after-meal glucagon, a hormone that raises blood sugar, helping prevent glucose spikes.
3. Slows gastric emptying: Delays the movement of food from the stomach to the intestines, which slows the absorption of glucose and increases feelings of fullness.
These combined effects lower blood sugar, decrease food intake, and reduce body weight.
What do the clinical trials show?
Mounjaro has been studied in the SURPASS clinical trial program. The five adult glycemic control trials in the label (SURPASS-1 to -5) randomized 6,278 adults with type 2 diabetes:
SURPASS-1 to -5 (Glycemic Control): With 5 mg, 10 mg, and 15 mg doses, average A1C fell by 1.7 to 2.4 percentage points after 40 to 52 weeks. Average body weight fell by 5.4 to 11.3 kg (about 12 to 25 pounds). Comparators were placebo, semaglutide 1 mg, insulin degludec, and insulin glargine (Mounjaro Prescribing Information, section 14).
SURPASS-2 (vs Semaglutide 1 mg): In 1,879 adults on metformin, A1C fell by 2.01, 2.24, and 2.30 percentage points with tirzepatide 5, 10, and 15 mg, vs 1.86 with semaglutide 1 mg. All three doses were superior to semaglutide. Weight loss was 1.9 to 5.5 kg greater with tirzepatide (SURPASS-2, NEJM 2021).
SURPASS-PEDS (Children 10 and Older): In 99 children and teens with type 2 diabetes, A1C fell by 2.0 percentage points with Mounjaro 5 mg or 10 mg vs 0.2 with placebo after 30 weeks (Mounjaro Prescribing Information, section 14.5).
SURPASS-CVOT (Cardiovascular Outcomes): In 13,299 adults with type 2 diabetes and established cardiovascular disease, Mounjaro was compared with dulaglutide 1.5 mg over a median of 210.1 weeks. Major adverse cardiovascular events (cardiovascular death, heart attack, or stroke) occurred in 12.1% on Mounjaro vs 13.0% on dulaglutide (hazard ratio 0.92, 95.3% CI 0.83 to 1.01). Mounjaro was noninferior to dulaglutide. Superiority was not established (Mounjaro Prescribing Information, section 14.6).
Common finding: Nausea, vomiting, and diarrhea were reported most often during dose increases and decreased over time. Gradual dose escalation helps minimize gastrointestinal side effects (Mounjaro Prescribing Information, section 6.1).
What should I discuss with my doctor?
Mounjaro is a prescription medication that requires medical supervision. Before starting, discuss:
- Your complete medical history, especially any history of pancreatitis, kidney disease, diabetic retinopathy, or thyroid cancer
- All medications you're taking, especially insulin or sulfonylureas (increased hypoglycemia risk when combined)
- Whether you're pregnant, planning to become pregnant, or breastfeeding
- Your insurance coverage and whether you qualify for manufacturer savings programs
- Realistic expectations for blood sugar control and weight loss
This is not medical advice. Only your healthcare provider can determine if Mounjaro is appropriate for you.
Frequently asked questions
Is Mounjaro approved for weight loss?
Mounjaro is not FDA-approved for weight loss. The same active ingredient (tirzepatide) is sold as Zepbound, which is FDA-approved for chronic weight management in adults with obesity, or overweight with at least one weight-related condition (Zepbound Prescribing Information). In the SURPASS-1 to -5 trials in adults with type 2 diabetes, average weight loss on Mounjaro was 5.4 to 11.3 kg (about 12 to 25 pounds), depending on dose and trial (Mounjaro Prescribing Information, section 14). Use Mounjaro for weight loss only under medical supervision.
How much does Mounjaro cost?
Without insurance, Mounjaro's list price is $1,112.16 per month, but the federal TrumpRx.gov self-pay price is $499 per month for every strength. With insurance, copays vary widely from $25 to $300+ depending on your plan. Eli Lilly offers a savings card that may reduce copays to $25 for up to 24 months for eligible commercially insured patients. Medicare and Medicaid coverage varies by plan and state.
What are the most common side effects?
The most common side effects are gastrointestinal. In placebo-controlled trials in adults (5 mg to 15 mg doses), rates were nausea 12-18%, diarrhea 12-17%, decreased appetite 5-11%, dyspepsia 5-8%, vomiting 5-9%, constipation 6-7%, and abdominal pain 5-6%. Most nausea, vomiting, and diarrhea happened during dose increases and decreased over time (Mounjaro Prescribing Information, section 6.1). Serious but rare risks include pancreatitis, gallbladder problems, kidney injury, diabetic retinopathy complications, and thyroid tumors (seen in animal studies, not yet confirmed in humans).