Mounjaro, also referred to as its active ingredient tirzepatide, belongs to the class of medications known as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonists. This dual action produces potent effects in lowering blood sugar levels in individuals with type 2 diabetes mellitus.

Despite its robust efficacy, as demonstrated in clinical trials, Mounjaro has the potential to cause a wide range of side effects. These side effects can range from mild to severe and could be temporary or long-term. Before starting Mounjaro therapy, it is important to be aware of the potential side effects and risks so that you can make informed decisions regarding your health before and during treatment.

What common side effects can Mounjaro cause?

Like any drug, Mounjaro can cause a wide array of side effects. Some of these effects happen more frequently than others, and some may last only a short time while others can persist for weeks at a time. Side effects commonly experienced in clinical trials, happening in more than five percent of individuals, were commonly related to gastrointestinal (GI) issues.

Mounjaro side effects include slowing gastric emptying due to its GLP-1 agonist properties, impacting how quickly food moves through the stomach. Likewise, prolonging gastric emptying can cause issues relating to your GI tract. These include things like nausea, vomiting, diarrhea, constipation, indigestion, stomach pain, and low appetite.

Should you find Mounjaro side effects particularly troubling or persistent, it’s important to consult your pharmacist or doctor for advice. Your provider may be able to provide strategies to manage side effects, lower your Mounjaro dose, or switch you to another medication altogether.

What other side effects can happen?

In addition to GI issues, clinical trials have identified a range of other Mounjaro side effects that patients may experience. Some other mild problems can occur, such as belching, acid reflux, gas, abdominal swelling, and injection site reactions (e.g., pain). These are all normal to experience, but again, if you find them troublesome or persistent, let your doctor know.

What serious adverse effects can Mounjaro cause?

While Mounjaro usually only causes mild side effects, in rare circumstances it can also cause serious adverse events. If you experience any of the below effects, seek medical attention immediately or call 911. Many of these conditions need to be treated as soon as possible. Let’s review adverse events that can happen.


One of the more serious Mounjaro side effects is pancreatitis, an inflammation of the pancreas that requires immediate medical intervention. In clinical trials, pancreatitis occurred in 13 cases in the Mounjaro group versus 3 cases in the comparator-treated patients. The risk of pancreatitis, specifically in those with a history of pancreatitis, is unknown.

Symptoms of pancreatitis include serious stomach pain and vomiting. Experiencing symptoms indicative of pancreatitis, a serious Mounjaro side effect, should prompt immediate medical attention.

Allergy to medication

As with any drug, Mounjaro carries the risk of allergic reactions. Clinical trials have reported instances of allergy, with symptoms such as eczema and itching. Other GLP-1 agonists are associated with the risk of angioedema (swelling under the skin) and anaphylaxis, which can be serious and life-threatening. If you experience allergy symptoms, stop Mounjaro treatment, and if serious, seek medical attention immediately. For more mild allergy symptoms, still, contact your doctor as soon as possible.


Hypoglycemia is an issue characterized by very low blood sugar levels. While antidiabetic treatment aims to lower blood sugar, we don’t want to do it so much that we deprive our bodies of energy. Sometimes, when we take several antidiabetic regimens at once, it can cause blood sugar levels to get too low. Thus, combining Mounjaro with insulin or insulin secretagogues (e.g., sulfonylureas) can increase your risk of hypoglycemia.

Your risk of hypoglycemia may be reduced by lowering the dose of your insulin or other antidiabetic medications. Your provider can help you do this if necessary. Additionally, you should be aware of the symptoms of hypoglycemia, which include: shakiness, sweating, paleness, hunger, headache, abnormal heartbeat, nausea, drowsiness, anxiety, and irritability.

Acute kidney injury

As aforementioned, Mounjaro can cause GI side effects like nausea, diarrhea, and vomiting. If you experience one or some of these effects, you may become dehydrated as a result. Dehydration can be serious, causing acute kidney injury (AKI). AKI happens when your kidneys suddenly stop functioning as they should. It can manifest as symptoms like low urine output, drowsiness, swelling in your eyes, ankles, or legs, shortness of breath, nausea, chest pain, and confusion.

Case reports of individuals on other GLP-1 agonists have indicated AKI or chronic renal failure worsening, sometimes in those with underlying kidney disease. Thus, caution should be used when taking Mounjaro if you have kidney impairment and are experiencing serious GI problems.

Serious GI disease

As we have mentioned, Mounjaro can cause serious GI reactions. Mounjaro has not been evaluated in those with serious GI diseases like gastroparesis and thus is not recommended in these individuals.

Acute gallbladder disease

Gallbladder disease is characterized by gallstones and mild inflammation, sometimes causing scarring and stiffness of the gallbladder. GLP-1 receptor agonists have been known to cause acute gallbladder disease events. With Mounjaro specifically, gallbladder issues occurred in 0.6 percent of patients on Mounjaro versus zero percent of patients treated with placebo. Gallbladder issues can present as symptoms such as nausea, gas, and stomach pain after meals.

Diabetic retinopathy

Diabetic retinopathy is a complication of diabetes that impacts the eyes. It happens when high blood sugar damages the blood vessels within the retina, potentially causing vision problems. When blood sugars are quickly improved with medications like Mounjaro, it may cause transient worsening of diabetic retinopathy. Thus, patients with diabetic retinopathy should be monitored if on Mounjaro.

Thyroid C-cell tumors

Animal models evaluated how tirzepatide, Mounjaro’s main ingredient, affected rats throughout a two-year study. In rats, it was found that tirzepatide was correlated with an increased incidence of thyroid C-cell tumors. It is unclear to experts if Mounjaro does the same in humans. Because of this potential risk, Mounjaro should not be used in individuals who have a history or family history of Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) or medullary thyroid carcinoma (MTC).

If you are starting Mounjaro, it is important to be aware of the potential MTC risk. Additionally, you should be aware of thyroid tumor symptoms, including trouble swallowing, trouble breathing, neck masses, and persistent hoarseness. Otherwise, the need for additional monitoring procedures is uncertain.

How long do the side effects last?

The length of time that you will experience side effects will depend on the type of side effect and its severity. Mild side effects like those affecting your GI system (e.g., nausea) may resolve after a few days or weeks as your body adjusts to the medication.

The more serious side effects mentioned above can be more long-term and require treatment. Thus, if you experience uncomfortable or persistent side effects, you should make your provider aware so that proper intervention and treatment can happen.

How can I manage the side effects?

If you experience serious side effects with Mounjaro, these will need to be managed under the supervision of your doctor. However, for more mild symptoms related to the GI tract, here are some tips:

  1. Change your eating habits
    1. Eat slowly
    2. Stop eating once you are full
    3. Eat smaller portions
    4. Do not eat meals near bedtime
    5. Eat meals more often
    6. Do not lay down after eating
    7. Do not be overly active immediately after a meal
    8. Do not eat amidst distractions
    9. Do not use a straw
  2. Change your food composition
    1. Eat a low-fat diet
    2. Avoid foods like sweets, canned foods, and dressings
    3. Stay hydrated, drinking clear drinks in small sips
    4. Boil, make, or griddle your food
    5. Eat foods that are rich in water
  3. Lifestyle changes
    1. Maintain a food diary to understand how food affects your symptoms
    2. Engage in light exercise
    3. Get fresh air

If despite these interventions you still experience something like nausea, certain anti-nausea medications may be able to be used.

Who should not use Mounjaro?

Certain individuals should not use Mounjaro because of the risks associated with their pre-existing conditions. These contraindications include:

  • Individuals with a history or family history of MTC or MEN-2
  • Individuals that are allergic to tirzepatide or other components of Mounjaro

If you are pregnant or may become pregnant, discuss with your doctor before starting Mounjaro. Mounjaro could potentially cause fetal harm.

Monitoring and Reporting Side Effects

When undergoing treatment with Mounjaro, it’s crucial for patients to actively monitor and report any side effects they experience. This vigilance is important for their safety and aids healthcare providers in managing the treatment more effectively.

How to Monitor Side Effects:

  1. Keep a Symptom Diary: Patients should maintain a daily log of their symptoms, noting the onset, duration, and severity of any side effects. This record can help in identifying patterns or triggers and provide valuable information to healthcare providers.
  2. Understand the Expected Side Effects: Being informed about the common and serious side effects of Mounjaro allows patients to recognize them early. Educational materials provided by healthcare providers or medication guides can be useful resources.
  3. Regular Health Check-ups: Regular appointments with healthcare providers are essential. These visits can include routine blood tests, kidney function tests, and other assessments to monitor the body’s response to the medication.

Importance of Reporting Side Effects:

  1. Adjusting Treatment: Reporting side effects promptly can help healthcare providers adjust the medication dosage or switch to an alternative treatment if necessary.
  2. Preventing Complications: Early detection and reporting of adverse effects like pancreatitis or severe allergic reactions can prevent serious complications.
  3. Contributing to Safe Usage: Patient reports contribute to a broader understanding of the medication’s impact, aiding in refining treatment guidelines and ensuring safer use for others.

When to Seek Medical Attention:

  • Immediate Attention: If symptoms of severe allergic reactions, pancreatitis, or other serious conditions as listed in the medication guide occur, patients should seek immediate medical attention.
  • Regular Appointments: Even for mild side effects, discussing them during regular check-ups is important. This discussion can lead to better management strategies.

Effective Communication with the Healthcare Team:

  • Be Specific and Detailed: When describing side effects, be as specific as possible about what is experienced, including the timing and impact on daily activities.
  • Ask Questions: Patients should feel empowered to ask their healthcare providers for any concerns or clarifications regarding their treatment and side effects.
  • Follow-up: After reporting side effects, patients should follow up to understand any changes in their treatment plan or additional steps they need to take.

Active monitoring and reporting of side effects are key components of effective diabetes management with Mounjaro. Patients should work closely with their healthcare team to ensure the best possible outcomes from their treatment.

Long-Term Effects:

Understanding the long-term effects of Mounjaro (tirzepatide) is crucial for patients and healthcare providers to make informed decisions about diabetes management. While Mounjaro has shown promising results in clinical trials, its relatively recent approval means that long-term data is still being gathered. However, some potential long-term effects, based on its mechanism of action and similarities with other GLP-1 agonists, may include:

  1. Gastrointestinal Adaptation: Initially, Mounjaro can cause gastrointestinal side effects like nausea and diarrhea. Over time, these symptoms may decrease as the body adapts to the medication.
  2. Weight Management: Mounjaro has been associated with weight loss in patients. Long-term use could contribute to sustained weight management, which is beneficial for type 2 diabetes patients.
  3. Cardiovascular Health: Given the drug’s impact on weight and blood sugar levels, there could be potential long-term benefits for cardiovascular health. Ongoing studies are likely to focus on this aspect.
  4. Pancreatic Health: The long-term impact on the pancreas, especially concerning the risk of pancreatitis, is a critical area of ongoing research.
  5. Thyroid Monitoring: Due to the observed effects in animal studies, long-term surveillance for thyroid-related issues might be necessary.

Updates on Ongoing Research:

Research on Mounjaro is ongoing, with several studies focusing on its long-term efficacy, safety, and broader impacts on health:

  • Extended Clinical Trials: Longer-term follow-up studies from existing clinical trials are expected to provide more data on the efficacy and safety of Mounjaro over extended periods.
  • Comparative Studies: Research comparing Mounjaro with other diabetes medications over the long term can offer insights into its relative effectiveness and side effect profile.
  • Real-World Data: Post-marketing surveillance and real-world studies will be crucial in understanding how Mounjaro performs outside the controlled environment of clinical trials.
  • Specific Population Studies: Ongoing research may also focus on the effects of Mounjaro in specific populations, such as those with varying degrees of diabetes severity, comorbidities, or different demographic backgrounds.

As more data becomes available, it will be essential to update the information provided to patients and healthcare providers to reflect the most current understanding of Mounjaro’s long-term effects and ongoing research findings.


Mounjaro is known to commonly cause GI side effects like nausea, vomiting, diarrhea, constipation, indigestion, stomach pain, and low appetite. These tend to be temporary, and your body should adjust with time. However, other more serious adverse events, though rare, can also occur with Mounjaro. Thus, if you experience severe symptoms or suspect a serious side effect, contact your doctor or seek medical attention right away.

Key Takeaways

  1. Mounjaro’s Dual Mechanism: Mounjaro (tirzepatide) works as both a GLP-1 and GIP receptor agonist, effectively lowering blood sugar in type 2 diabetes patients.
  2. Range of Side Effects: Mounjaro can cause a variety of side effects, ranging from mild to severe, and these may be temporary or long-term.
  3. Common Gastrointestinal Issues: The most frequent side effects are gastrointestinal, including nausea, vomiting, diarrhea, constipation, indigestion, stomach pain, and low appetite.
  4. Management of Side Effects: If side effects are severe or persistent, it’s important to consult a healthcare provider for management strategies or medication adjustments.
  5. Potential for Serious Adverse Effects: While rare, Mounjaro can cause serious conditions like pancreatitis, severe allergic reactions, hypoglycemia, acute kidney injury, serious GI disease, acute gallbladder disease, diabetic retinopathy, and thyroid C-cell tumors.
  6. Monitoring and Reporting Side Effects: Patients are advised to actively monitor and report side effects, maintaining a symptom diary and having regular health check-ups.
  7. Importance of Communication with Healthcare Providers: Effective communication about side effects with healthcare providers is crucial for safe and effective treatment.
  8. Contraindications: Mounjaro is not recommended for individuals with a history of certain thyroid cancers or those allergic to its components.
  9. Long-Term Effects and Ongoing Research: Long-term effects are still being studied, with ongoing research focusing on extended efficacy, safety, and specific population impacts.
  10. Informed Decision-Making: Understanding the potential side effects and risks of Mounjaro is essential for patients to make informed decisions about their diabetes treatment.