7 Mounjaro side effects you need to be aware of

Key Points

• The most common Mounjaro side effects to be aware of are diarrhea, vomiting, constipation, nausea (mild to moderate), decreased appetite, and abdominal pain. For most people, stomach side effects lessen or go away after a few weeks of treatment. Low blood sugar may also be common.
• More serious Mounjaro side effects are less common or rare but include a risk for thyroid cancer, inflammation of your pancreas (pancreatitis), gallstones, low blood sugar (hypoglycemia), kidney problems, diabetic eye issues, and severe gastrointestinal disease.

What is Mounjaro?

Mounjaro (tirzepatide) is a once-weekly injection used for type 2 diabetes in adults, to lower blood sugar levels. It should be used together with diet and exercise. Tirzepatide is a GIP and GLP-1 receptor agonist.

7 Mounjaro side effects and how to manage them

Let’s look at 7 of Mounjaro side effects, stomach problems, low blood sugar, allergic reactions, thyroid tumors, pancreatitis, kidney injury and gallbladder problems. Some side effects are common, and others are more serious or rare. The most common side effects are short-term and last only a few days or weeks. We’ll offer tips on how you can recognize and manage these side effects so you can stay on treatment and meet your weight loss goals.

1. Stomach problems

Mounjaro stomach side effects are common and well-known but are usually mild and clear up in a few weeks. The most common stomach or abdominal side effect of Mounjaro 10mg is nausea, which occurs in about 15% of people in clinical studies. Other stomach side effects include diarrhea (13%), decreased appetite (10%), heartburn (8%), vomiting (5%), constipation (6%), stomach-area pain (5%), bloating (2.9%), belching or gas (2.5%), flatulence (2.5%) and reflux (2.5%).

Stomach side effects tend to occur at the beginning of treatment and when your dose is increased too quickly. Because of this, your healthcare provider will slowly increase your dose every 4 weeks over a 16-week period until you reach your normal dose. You can use Mounjaro with or without food.

The good news is that for most people, these side effects are mild and temporary and will not interfere with long-term treatment. They typically subside within a few weeks of starting treatment.

The number of patients who discontinued Mounjaro due to stomach side effects was 3% for the 5mg dose, 5.4% for the 10mg dose, and 6.6% for the 15 mg dose.

Mounjaro is not recommended if there is a history of severe gastroparesis (slowed emptying of your stomach) or severe gastrointestinal disease.

Tips for managing stomach side effects

If you have stomach side effects like nausea when first starting treatment, you can help to manage it by:

• eating more slowly
• consuming smaller meals
• selecting more bland, low-fat foods (like crackers, toast and rice)
• avoiding greasy, fried foods
• eating foods that contain water (like soup or gelatin)
• not lying down after eating
• going outside for fresh air

If you experience stomach side effects with Mounjaro that bother you, worsen, or do not go away, call your healthcare provider for further evaluation.

2. Low blood sugar

Low blood sugar, also called hypoglycemia, can happen with Mounjaro treatment but is not a frequent side effect. The chances for this side effect may be greater if you also use basal insulin, with or without metformin. In clinical trials, patients using Mounjaro without basal insulin had no episodes of severe low blood sugar (less than 54 mg/dL).

In Mounjaro clinical trials involving patients who were also using basal insulin, with or without metformin, the number of patients who experienced severe low blood sugar (less than 54 mg/dL) was 13% for placebo patients, 15% for Mounjaro 5mg patients, 19% for Mounjaro 10mg and 14% for Mounjaro 15mg patients.

Tips for managing low blood sugar

Call your doctor right away if you have any of these signs or symptoms of low blood sugar:

• dizziness, feeling lightheaded or jittery
• headache
• feeling tired, drowsiness
• anxiety, irritability, or other mood changes
• blurred vision
• weakness or shakiness
• a fast heartbeat
• confusion
• slurred speech
• hunger
• sweating

Ask your doctor what you should do if you develop symptoms of low blood sugar. This may include taking glucose (sugar) tablets, a glucose liquid, fruit juice or using glucagon. You and your doctor may need to more closely monitor your blood sugar during treatment with Mounjaro.

Tell your healthcare provider if you are taking other medicines to treat diabetes, including sulfonylureas or insulin. Your doctor may need to change your dose of any type 2 diabetes medicines.

Do not exceed the dose of Mounjaro prescribed by your healthcare provider, which may increase your risk for low blood sugar.

3. Allergic Reactions

Serious hypersensitivity (allergic) reactions have been reported with the use of tirzepatide, the active ingredient in Mounjaro. In some people, these reactions may be life-threatening. If hypersensitivity reactions occur, stop using this medicine and seek immediate medical attention.

In clinical studies, hypersensitivity reaction affected 3.2% of Mounjaro-treated patients compared to 1.7% of placebo-treated patients.

Tips for managing allergic reactions

Stop taking this medicine and contact emergency medical services right away if you have any of these symptoms:

• swelling of your face, lips, mouth, tongue or throat
• trouble breathing, swallowing, or talking
• severe rash, hives, or itching
• very rapid heartbeat
• wheezing or feeling of chest tightness
• fainting or feeling dizzy
• blistered or peeling skin (with or without a fever)

Do not use Mounjaro if you are allergic to it or have had an allergic reaction to any tirzepatide product or its inactive ingredients. You can find a list of inactive ingredients in the package insert or ask your pharmacist.

4. Risk of thyroid tumors or thyroid cancer

Your thyroid is a small gland found in the front of your neck area. It helps to control many functions in your body by making and releasing certain hormones.

One of the most serious but rare warnings with Mounjaro includes a risk for thyroid tumors or thyroid cancer, which has been seen in rodent studies. It is not known if Mounjaro will cause thyroid tumors or thyroid cancer in humans, but it carries a Boxed Warning for this possible side effect, the FDA’s most prominent warning.

You should not use Mounjaro if you or anyone in your family have ever had a type of thyroid cancer called medullary thyroid carcinoma (MTC) or if you have an endocrine system condition called Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).

Cases of MTC have been seen in patients treated with another GLP-1 receptor agonist known as liraglutide (Saxenda, Victoza) after it was approved by the FDA. However, it is not known if liraglutide caused these tumors because there was not enough data in the reports to draw a final conclusion.

Your doctor will check your thyroid gland (found in your neck area) for nodules. A blood test (serum calcitonin) or a thyroid ultrasound (imaging test) may be used to monitor for thyroid disease, but this is not commonly done because the tests are not very specific. However, if your doctor suspects thyroid disease, they may order these tests and do further evaluations.

Tips for managing possible thyroid disease

If you notice any of the following signs or symptoms, contact your doctor right away:

• a lump or swelling in the neck
• neck pain
• a hoarse voice or voice changes
• trouble swallowing
• trouble breathing
• a cough that won’t go away

Related Questions

• How do Ozempic, Mounjaro, Wegovy, Zepbound compare for weight loss?
• Tirzepatide vs semaglutide: How do they compare?
• Can you get tirzepatide from a compounding pharmacy?

5. Acute pancreatitis

Your pancreas is an important organ that lies behind the lower part of your stomach. Your pancreas releases enzymes that aid digestion of food and makes hormones (insulin) that help manage your blood sugar (blood glucose). Acute pancreatitis is a sudden inflammation of your pancreas.

Acute pancreatitis was reported in studies with Mounjaro. According to clinical trials, acute pancreatitis was reported in studies in 13 patients taking Mounjaro vs. 3 comparator-treated patients.

Tips for management of acute pancreatitis

Acute pancreatitis can be a severe or even deadly side effect, so call your doctor right away and stop taking Mounjaro if you experience any of these signs or symptoms.

• severe stomach pain, that may radiate to your back
• severe pain in your back
• severe nausea (upset stomach)
• vomiting (throwing up)

If your doctor finds that you have developed acute pancreatitis, you will need to stop Mounjaro treatment, and your healthcare professional with start appropriate management.

Mounjaro has not been studied in patients with a history of pancreatitis. If you’ve previously had pancreatitis, it is not known if you are more at risk for a recurrence with this treatment. It is not known if this medicine can be used safely in people with a history of pancreatitis.

6. Gallbladder problems

Your gallbladder is a small, pouch-like organ located just below your liver. It stores bile that is produced by the liver. Bile is released from the gallbladder into the small intestine and helps to digest fat from your diet.

Mounjaro can cause problems with your gallbladder and the need for surgery, including gallstones (cholelithiasis) or gallbladder inflammation (cholecystitis). Sometimes rapid weight loss can cause gallbladder disease, but you don’t have to lose weight to have gallbladder problems, either.

While gallbladder disease is not as common as general stomach side effects with Mounjaro, it can be much more serious. In clinical studies, the occurrence of acute gallbladder disease (cholelithiasis, biliary colic, and cholecystectomy) affected 0.6% of those who received Mounjaro and affected none of the patients who received a placebo (an inactive shot).

Tips for managing gallbladder disease

If you experience any of the following, contact your healthcare provider right away to be evaluated for possible gallbladder inflammation or gallstones:

• pain in the upper right area of your stomach
• pain in the right shoulder or between the shoulder blades
• yellowing of your skin or eyes (jaundice)
• a fever with chills
• dark-colored urine
• light-colored (clay-colored) stools

7. Acute Kidney Injury

Mounjaro can cause side effects of nausea, vomiting, and diarrhea, which may lead to a patient becoming dehydrated and, if this is severe, may cause acute kidney injury.

Tips for managing dehydration

People who have diarrhea, nausea, and vomiting side effects may lose body fluids (dehydration), which can cause kidney injury. Drinking fluids can help reduce the chance of dehydration. Contact your healthcare provider if you have any concerns.

If you experience any of the following, contact your healthcare provider right away to be evaluated for possible kidney injury:

• Decreased urine (pee) output, although occasionally urine output remains normal
• swelling in your legs, ankles or feet
• Shortness of breath
• Tiredness
• Confusion
• Nausea and vomiting
• pain on the side of your back - between your ribs and hips
• Weakness
• Irregular heartbeat
• Chest pain or pressure
• Seizures or coma in severe cases

These are not all of the side effects that occur with Mounjaro. Learn more here: Mounjaro side effects (in more detail)

You can also review a complete list of side effects in the manufacturer's Medication Guide. If you need a copy, you can get one from your pharmacist or doctor.

Bottom Line

• Mounjaro (tirzepatide) is a once-a-week injection used to treat adults with type 2 diabetes
• The most common side effects of Mounjaro are stomach-related and include nausea, diarrhea, vomiting, constipation, and pain in the stomach area. For most people, stomach side effects lessen or go away after a few weeks of treatment but can be severe in a small number of patients.
• Low blood sugar (hypoglycemia) can also be a serious and common side effect, especially in people taking certain type 2 diabetes medicines such as basal insulin.
• Other serious but less common or rare side effects with Mounjaro include a risk for thyroid cancer or tumors, which has been seen in animal studies, inflammation of your pancreas (pancreatitis), gallbladder disease (like gallstones), acute kidney damage, and severe, possibly life-threatening allergies.

This is not all the information you need to know about Mounjaro (tirzepatide) for safe and effective use and does not take the place of your doctor’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.