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Mounjaro Side Effects

Generic name: tirzepatide

Medically reviewed by Last updated on Dec 24, 2022.

Note: This document contains side effect information about tirzepatide. Some dosage forms listed on this page may not apply to the brand name Mounjaro.

Applies to tirzepatide: subcutaneous solution.


Subcutaneous route (Solution)

Risk of Thyroid C-Cell TumorsIn 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 tirzepatide 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. Tirzepatide 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 tirzepatide 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 tirzepatide.

Serious side effects of Mounjaro

Along with its needed effects, tirzepatide (the active ingredient contained in Mounjaro) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking tirzepatide:

More common

Less common

Incidence not known

Other side effects of Mounjaro

Some side effects of tirzepatide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

For Healthcare Professionals

Applies to tirzepatide: subcutaneous solution.


The most common adverse reactions reported in 5% of patients or greater treated with this drug included nausea, diarrhea, decreased appetite, vomiting, constipation, dyspepsia, and abdominal pain.[Ref]


In pooled placebo-controlled trials, treatment with this drug resulted in a mean increase in heart rate of 2 to 4 beats per minute compared to a mean increase of 1 beat per minute in placebo-treated patients. Episodes of sinus tachycardia (associated with a concomitant increase from baseline in heart rate of at least 15 beats per minute) were reported in up to 23% of patients. The clinical relevance of increased heart rate was uncertain.

Very common (10% or more): Sinus tachycardia (up to 23%)

Frequency not reported: Increased heart rate


In pooled placebo-controlled trials, treatment with this drug resulted in mean increases from baseline in serum pancreatic amylase levels of up to 38% and serum lipase levels of up to 42%; placebo-treated patients had a mean increase from baseline in pancreatic amylase of 4% and no changes were observed in lipase. The clinical significance of elevations in lipase or amylase with this drug was unknown without other signs/symptoms of pancreatitis.

Very common (10% or more): Nausea (up to 18%), diarrhea (up to 17%)

Common (1% to 10%): Vomiting, constipation, dyspepsia, abdominal pain, eructation, flatulence, gastroesophageal reflux disease, abdominal distension

Uncommon (0.1% to 1%): Cholelithiasis, acute pancreatitis, increased serum pancreatic amylase levels, increased serum lipase levels, acute gallbladder disease (including cholelithiasis, biliary colic and cholecystectomy)

Postmarketing reports: Ileus


Uncommon (0.1% to 1%): Acute gallbladder disease (cholelithiasis, biliary colic, cholecystectomy)


Common (1% to 10%): Hypersensitivity reactions (e.g., urticaria, eczema)

Postmarketing reports: Anaphylaxis, angioedema


Very common (10% or more): Anti-drug antibodies (up to 51%)

Common (1% to 10%): Neutralizing antibodies


Common (1% to 10%): Injection site reactions


Very common (10% or more): Hypoglycemia (up to 19%), decreased appetite (up to 11%)

Common (1% to 10%): Hyperglycemia

Hypoglycemia (glucose level less than 54 mg/dL) occurred more frequently when this drug was used in combination with a sulfonylurea (up to 13% of patients in a clinical trial); severe hypoglycemia occurred in up to 6% of patients. Hyperglycemia occurred more frequently in the placebo group versus in patients treated with this drug.


Common (1% to 10%): Fatigue, including asthenia, malaise, lethargy

Uncommon (0.1% to 1%): Blood calcitonin increased


Postmarketing reports (in other GLP-1 receptor agonists): Acute kidney injury, worsening of chronic renal failure


Very common (10% or more): Nasopharyngitis (10.5%)

Frequently asked questions


1. Product Information. Mounjaro (tirzepatide). Eli Lilly and Company Ltd. 2023.

2. Product Information. Mounjaro (tirzepatide). Lilly, Eli and Company. 2023.

3. Product Information. Mounjaro (tirzepatide). Eli Lilly Australia Pty Ltd. 2023.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.