Tirzepatide: What to Know Before You Take It
Also known as Mounjaro, Zepbound
Other names: mounjaro, zepbound
Tirzepatide is a once-weekly injectable peptide that activates both glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptors. It is FDA-approved for type 2 diabetes (Mounjaro) and chronic weight management (Zepbound).
FDA boxed warning
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 [see Warnings and Precautions ( 5.1 ) and Nonclinical Toxicology ( 13.1 )]. 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) [see Contraindications ( 4 )] . 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 [see Contraindications ( 4 ) and Warnings and Precautions ( 5.1 )]. WARNING: RISK OF THYROID C-CELL TUMORS See full prescribing information for complete boxed warning. In rats, tirzepatide causes thyroid C-cell tumors. It is unknown whether ZEPBOUND causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as the human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined ( 5.1 , 13.1 ). 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 of MTC and symptoms of thyroid tumors ( 4 , 5.1 ).
In plain language
What Tirzepatide is used for
- Type 2 diabetes glycemic control
- Chronic weight management (BMI ≥30, or ≥27 with weight-related condition)
- Cardiovascular risk reduction (emerging evidence)
Taking this medicine
How it is administered
- Subcutaneous injection (weekly)
Read before you decide
Risks and precautions
Risks and warnings
- Nausea, vomiting, diarrhea, abdominal pain, constipation
- Risk of thyroid C-cell tumors (animal data; black box warning)
- Pancreatitis (rare)
- Hypoglycemia when combined with insulin or insulin secretagogues
Who should not take it
- Personal or family history of medullary thyroid carcinoma
- Multiple endocrine neoplasia syndrome type 2 (MEN 2)
- Pregnancy or planned pregnancy
- Breastfeeding
Medication review
Tirzepatide drug interactions
FDA safety data
Most-reported side effects
Based on 140,435 FAERS reports. Reports do not prove the drug caused the effect.
Common questions
Patient questions
Is tirzepatide FDA-approved for weight loss?
Yes. Tirzepatide is FDA-approved under the brand name Zepbound for chronic weight management in adults with a BMI of 30 or greater, or 27 or greater with at least one weight-related condition, when used alongside a reduced-calorie diet and increased physical activity.
How is tirzepatide different from semaglutide?
Tirzepatide activates both GLP-1 and GIP receptors, while semaglutide activates only GLP-1 receptors. Clinical trials have suggested tirzepatide may produce greater average weight reduction, though individual responses vary and a provider determines which is appropriate for you.
Related medications
Explore treatment hubs
Access and affordability
Ways to save on Tirzepatide
Provides Lilly medicines at no cost to eligible patients who are U.S. residents, meet income requirements, and are uninsured or have Medicare Part D. Commercial savings cards are offered separately for insured patients.
Visit programThis information is educational — not medical advice.
This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.
Sources & References
- FDA structured product labeling for Tirzepatide
- U.S. Food & Drug Administration — openFDA Drug Labeling API
- U.S. National Library of Medicine — RxNorm drug nomenclature
- FDA label: Mounjaro (tirzepatide)
- FDA label: Zepbound (tirzepatide)
- NIH MedlinePlus: Tirzepatide injection
Learn more about where our data comes from and how we write and review medical content.