Mounjaro Side Effects: Causes & Treatments

Learn about the causes and treatments for known side effects associated with Mounjaro (tirzepatide), the injectable medication used in treating type 2 diabetes and obesity. Find out if Mounjaro is the best tool to help you achieve your health goals.

Table of Contents
  • What is Mounjaro?
  • Who Should Take Mounjaro?
  • Mounjaro Most Common Side Effects
  • Mounjaro Least Common Side Effects
  • Mounjaro Proper Use and Dosage

What is Mounjaro?

Mounjaro, the brand name for the active ingredient Tirzepatide, has made waves since its FDA approval in Spring 2022. Initially approved for managing type 2 diabetes, this medication has garnered attention for its off-label use in weight loss. Subsequently, the FDA granted approval for chronic weight management in individuals struggling with overweight or obesity.

What sets Mounjaro apart is its unique dual mechanism of action on GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 receptors. It's like having a single key to unlock two distinct doors. By engaging GLP-1 and GIP receptors, Mounjaro boosts glucose-dependent insulin secretion, curbs inappropriate glucagon secretion, slows gastric emptying, and reduces food intake. This multifaceted approach significantly enhances its effectiveness in managing both weight and blood sugar levels, making it a powerful tool in tackling metabolic disorders (1,2).

Who Should Take Mounjaro?

If you're struggling with weight loss despite making lifestyle changes, you might be a candidate for Mounjaro. To qualify for Mounjaro, certain criteria must be met. Firstly, individuals with obesity, defined by a Body Mass Index (BMI) exceeding 30 Kg/m^2, are eligible. Additionally, those with a BMI falling within the range of 27 to 29.9 Kg/m^2 may also be considered if they have one or more weight-related comorbidities. These comorbidities could include conditions such as type 2 diabetes, high blood pressure, or sleep apnea, among others. Mounjaro offers hope for individuals who have struggled to shed excess weight through traditional methods alone, providing a potential pathway to improved health and well-being.

Why should individuals meeting the criteria consider taking Mounjaro? A randomized controlled trial, detailed in the New England Journal of Medicine, sheds light on its efficacy. The study involved 2,539 adults with a BMI of 30 or BMI of 27 with comorbidities, excluding type 2 diabetes. Participants were divided into groups receiving weekly injections of Tirzepatide at doses of 5mg, 10mg, and 15mg, or a placebo, and were monitored for 72 weeks.

The findings were compelling: individuals who received Mounjaro lost significant weight over the study period. Specifically, those on the 5mg, 10mg, and 15mg doses saw weight reductions of 15%, 19.5%, and 20.9%, respectively, compared to a mere 3.1% change in the placebo group (1). This evidence underscores Mounjaro's potency as a formidable tool in the fight against obesity, offering hope to those striving to achieve meaningful weight loss and improve overall health.

Mounjaro Most Common Side Effects


Constipation affects 6-17% of Mounjaro patients  (3). It's likely due to the medication slowing down intestinal movement. To prevent this, aim for 25-35 grams of fiber daily. If diet alone isn't enough, try supplements like Meta Mucil or Psyllium Husk. Fiber helps by adding bulk and softening stools, making them easier to pass.


Surprisingly, 12-23% of patients experience diarrhea on Mounjaro (3). The cause isn't clear. Stay hydrated with water to replace lost fluids. Try foods like bananas, oatmeal, or white rice to bulk up loose stools.


Nausea affects 12-29% of patients (3). It may be due to Mounjaro slowing the digestive system or affecting appetite centers. Aromatherapy can help—try sniffing an alcohol pad or a freshly cut lemon. If it persists, talk to your doctor about medications like Zofran.


Vomiting is common, occurring in 5-13% of patients (3). It's unpleasant and can lead to dehydration. Stay hydrated and consider anti-nausea medications, as controlling nausea can often prevent vomiting.

Mounjaro Least Common Side Effects

Acute Kidney Injury

Rarely, patients taking Mounjaro may experience kidney injury, especially with persistent or severe vomiting and diarrhea. This occurs because excessive fluid loss through these symptoms reduces blood volume, potentially leading to decreased blood flow to the kidneys and subsequent injury. Symptoms of kidney injury include decreased urination, leg swelling, and confusion. It's important to inform your healthcare provider if you experience vomiting or diarrhea while on Mounjaro to monitor your condition and prevent kidney complications (4).

Worsening Diabetic Retinopathy

Diabetic retinopathy is a complication of diabetes where prolonged high blood sugar levels harm the blood vessels supplying the retina, potentially causing vision problems and even blindness over time. For patients using a GLP-1 agonist like Mounjaro, quickly bringing down blood sugar levels in those with existing diabetic retinopathy can worsen the condition. While rare, this side effect is significant, especially for individuals struggling to control their diabetes (5).


Pancreatitis, the inflammation of the pancreas, is a rare side effect observed in clinical trials of Mounjaro (6). While its frequency hasn't been precisely defined, it's crucial to recognize the symptoms. These typically include severe abdominal pain, often described as sharp and radiating to the back, accompanied by nausea, vomiting, and an inability to tolerate food. If you experience these symptoms, seek immediate medical assistance by contacting your doctor or going to the emergency department. Early intervention is vital in managing pancreatitis effectively.

Gallbladder Disease

Gallbladder disease covers a range of issues like biliary colic, cholecystitis, cholestasis, cholangitis, and cholecystectomy. These conditions involve gallstones and inflammation in the gallbladder and bile ducts, which play a key role in digesting fats. On Mounjaro, the risk of developing any of these diseases is around 0.2%. While the exact way GLP-1 medications contribute to these issues isn't fully understood, factors like higher doses, longer treatment durations, and rapid weight loss can increase the risk. It's worth noting that obesity is a risk factor for these diseases, regardless of Mounjaro use (7).

Medullary Thyroid Carcinoma

Currently, it's uncertain whether Mounjaro causes thyroid cancer in humans. This concern arose from early studies where thyroid cancer was observed in animals, though not in primates. While this is a consideration, it's worth noting that humans have fewer thyroid cells and fewer GLP-1 receptors in this organ compared to rodents. However, individuals with a personal or family history of medullary thyroid cancer may face an increased risk and should steer clear of this medication (8).

Mounjaro Proper Use and Dosage

Mounjaro, a once-weekly self-administered injection, offers convenience and ease of use. Simply cleanse the injection site (such as the abdomen or thigh) with an alcohol wipe, unlock the pen, and press and hold the button for up to 10 seconds, listening for two clicks indicating the start and completion of the injection.

The dosing regimen starts at 2.5 mg once weekly for 4 weeks, then increases to 5 mg once weekly. If necessary, the dose can be further increased by 2.5 mg per week every 4 weeks, up to a maximum of 15 mg per week. The lower initial dose of 2.5 mg aims to minimize gastrointestinal symptoms (e.g nausea, vomiting, constipation) but may not lead to significant weight loss. If a dose is missed, administer it as soon as possible within 4 days and resume the usual schedule thereafter. If more than 4 days have passed, skip the missed dose and continue with the next scheduled weekly dose.


  1. Jastreboff, A. M., Aronne, L. J., & Stefanski, A. (2022). Tirzepatide Once Weekly for the Treatment of Obesity. Reply. The New England Journal of Medicine, 387(15), 1434–1435.
  2. de Mesquita, Y. L. L., Pera Calvi, I., Reis Marques, I., Almeida Cruz, S., Padrao, E. M. H., Carvalho, P. E. de P., da Silva, C. H. A., Cardoso, R., Moura, F. A., & Rafalskiy, V. V. (2023). Efficacy and safety of the dual GIP and GLP-1 receptor agonist tirzepatide for weight loss: a meta-analysis of randomized controlled trials. International Journal of Obesity, 47(10), 883–892.
  3. Karrar, H. R., Nouh, M. I., Nouh, Y. I., Nouh, M. I., Khan Alhindi, A. S., Hemeq, Y. H., Aljameeli, A. M., Aljuaid, J. A., Alzahrani, S. J., Alsatami, A. A., Alkredees, M. A., Almuqati, A. O., Abanmi, S. N., & Alshehri, A. M. (2023). Tirzepatide-Induced Gastrointestinal Manifestations: A Systematic Review and Meta-Analysis. Curēus (Palo Alto, CA), 15(9), e46091–e46091.
  4. Aleman Espino, A., Aleman Espino, E., Aleman Oliva, C., Monteagudo, H., & Frontela, O. (2023). An Incidental Finding of a Glucagon-Like Peptide 1 (GLP-1)-Induced Acute Kidney Injury: A Case Report. In Cureus (Vol. 15, Issue 9, pp. e45261–e45261).
  5. Simo, R., & Hernoandez, C. (2017). GLP-1R as a Target for the Treatment of Diabetic Retinopathy: Friend or Foe? Diabetes (New York, N.Y.), 66(6), 1453–1460.
  6. Yadav, D., & Lowenfels, A. B. (2013). The Epidemiology of Pancreatitis and Pancreatic Cancer. Gastroenterology (New York, N.Y. 1943), 144(6), 1252–1261.
  7. Korkmaz, H., Araz, M., Alkan, S., & Akarsu, E. (2015). Liraglutide-related cholelithiasis. Aging Clinical and Experimental Research, 27(5), 751–753.
  8. FDA drug safety communication: FDA investigating reports of possible increased risk of pancreatitis and pre-cancerous findings of the pancreas from incretin mimetic drugs for type 2 diabetes. Food and Drug Administration. Updated February 21, 2018. Accessed April 16, 2024.

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