Home Drugs Mounjaro


Mounjaro is an FDA-approved injectable medication for type 2 diabetes. When used with a proper diet and exercise, the active ingredient tirzepatide activates GIP and GLP-1 receptors to support blood sugar regulation, slow gastric emptying, decrease food consumption and reduce insulin sensitivity.

Last Modified: January 29, 2024
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What Is Mounjaro?

Mounjaro is the brand name for Eli Lilly’s injectable type 2 diabetes drug with the active ingredient tirzepatide. Mounjaro works by mimicking the action of hormones in the body that activate the GLP-1 and GIP receptors. In trials, it helped patients to effectively regulate blood sugar levels and achieve lower A1c numbers.

The FDA approved Mounjaro for use in adults to help control blood sugar levels and lower insulin sensitivity. Patients should use it coupled with a balanced diet and exercise program for maximal results.

“Mounjaro is a first-in-class medicine that activates both the GLP-1 and GIP receptors, which leads to improved blood sugar control.” — FDA Approval Announcement, May 13, 2022”

Mounjaro works similarly to weight loss drugs such as Ozempic, and many people experience weight loss while taking it. However, it is only FDA-approved to treat type 2 diabetes.

How To Take Mounjaro

Patients administer weekly Mounjaro injections under the skin through a pre-filled single-use dosing pen. The design of each prefilled pen ensures proper dosing. Clinical trials evaluated three different dosages of tirzepatide: 5 mg, 10 mg and 15 mg. Patients begin using an initial 2.5 mg dose for four weeks. This allows the body to adjust to Mounjaro gradually. After four weeks, they move to a maintenance dose of 5 mg.

Some patients require higher doses of tirzepatide to achieve optimal results. Doctors may opt to increase medication by 2.5 mg each month until blood sugar levels stabilize. The maximum dose of Mounjaro is 15 mg.

Mounjaro Dosage Table
Starting DoseMaintenance DoseMaintenance DoseMaintenance DoseMaintenance DoseMaintenance Dose
2.5 mg5 mg7.5 mg10 mg12.5 mg15 mg
Weekly injections for at least 4 weeksWeekly injections for at least 4 weeksWeekly injections for at least 4 weeksWeekly injections for at least 4 weeks
Move to higher dose for greater glycemic controlMove to higher dose for greater glycemic controlMove to higher dose for greater glycemic controlMove to higher dose for greater glycemic controlMaximum dose

Mounjaro injection pens require refrigeration for long-term storage but remain safe and viable for up to three weeks at room temperature. Patients who miss a dose should take it as soon as possible, up to four days after missing the dose. If more than four days have passed, skip the dose and resume injections on the next scheduled date.

Can Mounjaro Be Used for Weight Loss?

Many patients lose a significant amount of weight on Mounjaro, but the FDA has not approved it for that purpose at this time. Eli Lilly received a fast-track designation for its application for FDA approval of tirzepatide for weight loss in patients diagnosed with obesity or overweight, now known as the brand Zepbound.

Many doctors prescribe Mounjaro for patients seeking to lose weight; however, this is an unapproved, or off-label, use. Anyone considering taking Mounjaro for weight loss should talk to their health care provider about the risks associated with off-label use of the medication. Keep in mind that purchasing medications online or from compounding pharmacies can expose you to additional risks of counterfeit products.

How Does Mounjaro Work?

Mounjaro works by activating GIP and GLP-1 receptors, which increases insulin sensitivity, alerts the pancreas to release more insulin after eating and stops the liver from producing excess sugar. This results in more controlled blood sugar levels. It also slows the rate at which food leaves the stomach, which causes patients to feel full longer. As a result, many patients taking Mounjaro report significant weight loss.

How Mounjaro Works
  • Activates GIP and GLP-1 receptors
  • Slows gastric emptying
  • Lowers the amount of sugar produced by the liver
  • Increases insulin production

The body naturally releases the hormones glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 after eating. These chemicals signal the pancreas to release insulin. Mounjaro works by stimulating the receptors for these hormones and increasing the efficiency of this natural function.

Side Effects of Mounjaro

Many patients experience gastrointestinal side effects while taking Mounjaro. Loss of appetite is also common due to delayed gastric emptying.

Common Mounjaro Side Effects
  • Diarrhea
  • Nausea
  • Reduced appetite
  • Stomach upset
  • Vomiting

Side effects of Mounjaro are generally most pronounced at the start of treatment or immediately after dosage increases. Symptoms decrease over time, although some patients may stop treatment because of them. Patients should discuss any side effects with a health care provider.

Serious Mounjaro Side Effects

More serious potential side effects of Mounjaro include low blood sugar, pancreatitis and issues with other organs. Additionally, some patients may experience a severe allergic reaction requiring immediate medical intervention. Anyone experiencing a serious side effect after taking Mounjaro should talk to a doctor about their symptoms immediately.

Serious Mounjaro Side Effects
  • Gallbladder problems
  • Hypoglycemia (low blood sugar)
  • Kidney problems
  • Severe stomach pain
  • Vision changes

Severe stomach pain may be a symptom of pancreatitis or inflammation of the pancreas. This typically causes severe abdominal pain that wraps around to the back. Vomiting may or may not be present.

Hypoglycemia is another serious side effect of Mounjaro. Common symptoms of the condition include blurry vision, dizziness, drowsiness, headaches and feeling jittery. Some people also experience mood changes and irritability.

If you experience serious side effects after using Mounjaro, you may be eligible for compensation.

Mounjaro Boxed Warning and Precautions

The FDA requires that all Mounjaro packaging includes a boxed warning about the risk of thyroid tumors. This is the highest level of warning the FDA can assign to a drug. Clinical studies showed an increased risk of thyroid tumors in rats taking tirzepatide.

Anyone with a family or personal history of thyroid cancer should avoid taking tirzepatide. Additionally, anyone taking Mounjaro who experiences signs of thyroid tumors, including hoarseness, lumps in the neck and difficulty swallowing, should report the symptoms to their doctor.

Additional Warnings for Mounjaro

Mounjaro packaging carries additional warnings for potentially serious side effects of the drug’s use, including diabetic retinopathy and gastroparesis. Individuals taking tirzepatide have experienced these conditions during regular use or while enrolled in clinical trials. Doctors should discuss with patients the possibility of these conditions developing while taking Mounjaro.

Mounjaro Warnings
Acute Gallbladder Disease
A small percentage (0.6%) of individuals taking Mounjaro in clinical trials developed symptoms of acute gallbladder disease.
Acute Kidney Injury
Severe gastrointestinal symptoms associated with Mounjaro use may contribute to dehydration. If it persists, it may cause acute kidney injury.
Diabetic Retinopathy
Mounjaro may contribute to worsening symptoms in some patients with a history of diabetic retinopathy.
Mounjaro contributes to delayed gastric emptying. This may become severe and result in a paralysis of the stomach, which stops emptying altogether.
Hypersensitivity Reactions
Some patients may experience an allergic reaction to tirzepatide. Anaphylaxis is a possible outcome for those with a hypersensitivity to the drug.
Mounjaro may contribute to hypoglycemia when used with insulin or an insulin secretagogue.
Some patients treated with GLP-1 receptor agonists have displayed symptoms of acute pancreatitis.

Adverse effects of Mounjaro can be serious or even life-threatening. Patients should report all unusual symptoms to a health care provider.

Several patients who experienced severe side effects after taking Mounjaro filed lawsuits against Eli Lilly. These lawsuits claim Mounjaro caused gastroparesis and severe vomiting lasting for weeks despite treatment. They further claim that Eli Lilly failed to provide adequate warnings about these and other possible adverse reactions.

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Is There a Mounjaro Shortage?

An overwhelming demand for GLP-1 receptor agonists like Mounjaro has contributed to shortages of the drugs. Eli Lilly initially struggled to meet the demand for Mounjaro but is working to resolve supply shortages. As of December 2023, the FDA’s drug shortages database listed all doses of Mounjaro as “available,” yet the drug remained on its shortages list.

Patients may need to call multiple pharmacies to find the initial 2.5-mg Mounjaro dosage pen. If shortages resume, they will need to repeat the process for each succeeding increase in Mounjaro dosage. The FDA lists Eli Lilly’s contact number related to shortages as 800-545-5979.

Please seek the advice of a medical professional before making health care decisions.