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by Kyle Davies on Jul 10, 2025

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What is Mounjaro? The Unique GLP-1 and GIP Drug for Type 2 Diabetes

Mounjaro is a next-generation tirzepatide treatment from Eli Lilly, combining glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor activation for enhanced blood sugar and weight control in adults with type 2 diabetes (T2D).

Due to its dual-action mechanism and higher dose potency of up to 15 mg per week, Mounjaro may offer superior blood sugar control compared to some of the other glucagon-like peptide-1 (GLP-1) receptor agonists used for T2D care, such as Ozempic with the maximum approved dose of 2 mg and Trulicity (4.5 mg). At maintenance dose alongside metformin, Ozempic, one of the leading GLP-1 treatments for type 2 diabetes, can reduce haemoglobin A1c (HbA1c), a key indicator of average blood glucose, by up to 2.1%. In comparison, a 15 mg maintenance dose of tirzepatide has shown reductions of up to 2.3% in patients on metformin.

Mounjaro also supports more substantial weight loss, with users achieving an average reduction of 11% over approximately 40 weeks, compared to around 7.5% with Ozempic over 40 to 52 weeks at maintenance dose. Additionally, tirzepatide has demonstrated heart health benefits, reducing the risk of cardiovascular death or worsening heart failure by 38% in the SUMMIT trial involving 731 adults with obesity and heart failure with preserved ejection fraction.

Find out how Mounjaro works, its approved uses and potential side effects.

What Is Mounjaro and How Does It Work?

Tirzepatide, the active ingredient in Mounjaro, is a synthetic peptide with a distinctive dual agonist mechanism. It targets two hormone receptors in the body, GLP-1and GIP, to support blood sugar regulation in adults with type 2 diabetes and weight management in adults with weight-related health problems.

Like earlier GLP-1 receptor agonists used in type 2 diabetes care, such as Ozempic, Trulicity, and Rybelsus, tirzepatide is designed to mimic the human GLP-1 hormone, with specific structural modifications to extend its duration of action. Natural GLP-1 stimulates insulin secretion, suppresses glucagon release, delays gastric emptying, and promotes a feeling of fullness after eating. These effects help regulate blood sugar in a glucose-dependent manner, reducing the risk of hypoglycaemia.

However, native GLP-1 breaks down rapidly, within one to two minutes, due to enzymatic degradation. Tirzepatide overcomes this limitation by incorporating only a part of the amino acid sequence of human GLP-1 and leveraging chemical modifications that prolong its half-life to approximately five days. This enables convenient once-weekly dosing.

Moreover, Tirzepatide mimics the action of the GIP hormone, which is naturally produced in the small intestine and enhances insulin secretion following food intake. The native form of GIP also has a very short half-life, approximately seven minutes. Tirzepatide, however, extends receptor activation significantly, enhancing its overall therapeutic impact.

By combining GLP-1 and GIP receptor activation, tirzepatide delivers powerful glycaemic control. It effectively lowers average blood glucose, as well as both fasting and postprandial levels, while maintaining a low risk of hypoglycaemia. In addition to improving metabolism, it supports significant weight loss and has been associated with a reduced risk of all-cause mortality in people with type 2 diabetes. Evidence also suggests a lower incidence of major adverse cardiovascular events (MACEs) and fewer kidney-related complications with tirzepatide treatment.

What Is Mounjaro used for?

Mounjaro is currently approved for treating type 2 diabetes mellitus. In the European Union, it has also been authorised for weight management in individuals with obesity or overweight-related health conditions. For this indication, Zepbound, another tirzepatide-based formulation from Eli Lilly, has been approved in the United States.

Mounjaro for type 2 diabetes

Mounjaro received its initial approval from the United States Food and Drug Administration on 13 May 2022 for the treatment of type 2 diabetes in adults. It is indicated as an adjunct to diet and physical activity to improve glycaemic control in individuals with T2D.

It may be used as monotherapy when metformin is not appropriate or in combination with other anti-diabetic medications, including metformin, sodium-glucose co-transporter 2 (SGLT2) inhibitors, sulfonylureas, or insulin.

Mounjaro - weight-loss prescription

In the European Union, Mounjaro is approved for chronic weight management alongside dietary and lifestyle changes in adults.

Mounjaro is indicated for:

Adults with a BMI of 30 kg/m² or higher (classified as obesity), or
Adults with a BMI between 27 and 30 kg/m² (classified as overweight) who also have at least one weight-related condition like T2D, high cholesterol (dyslipidaemia), high blood pressure (hypertension), or obstructive sleep apnoea.

Contraindications and precautions

Mounjaro is contraindicated in individuals with:

A personal or family history of medullary thyroid carcinoma (MTC), or multiple endocrine neoplasia syndrome type 2 (MEN 2), due to tumour findings in animal studies, although human relevance is unknown.
Known hypersensitivity to tirzepatide or any of its components.
Type 1 diabetes mellitus, as the drug is not approved for this condition.
Pregnancy, due to potential risk to the foetus based on animal data.
Age under 18, as it has not been studied in children or adolescents.

Mounjaro may be unsuitable or should be used with caution in patients with:

Severe gastrointestinal disease, due to the lack of safety data.
A history of pancreatitis, as safety has not been established.
Gallbladder disease, due to reported gallbladder-related events.
Upcoming surgery or sedation, as delayed gastric emptying may increase aspiration risk.
Diabetic retinopathy complications, which may temporarily worsen with rapid glycaemic improvement.
Renal impairment or a history of acute kidney injury, as dehydration from gastrointestinal side effects may further affect kidney function.
Risk of hypoglycaemia, particularly when used with insulin or sulfonylureas.

Additional Considerations

Due to its effect on gastric emptying, tirzepatide may reduce the effectiveness of oral medications. Therefore, an alternative to oral contraception is recommended during the treatment and for four weeks after any dose change. For the same reason, adjustments to other oral therapies may be necessary.

Mounjaro Injection: Dosage Strengths and Composition

Mounjaro is supplied as a ready-to-use, single-dose solution for under-the-skin injection, available in prefilled pens or vials. The Mounjaro pen contains only one active ingredient, tirzepatide, available in six dosage strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg, each delivered in 0.5 mL of solution.

In addition to tirzepatide, the Mounjaro pen contains several excipients, including:

Sodium phosphate dibasic heptahydrate, which acts as a buffer to maintain pH stability.
Sodium chloride, an isotonicity agent to match body fluids.
Benzyl alcohol, serving as a preservative and antimicrobial agent.
Glycerol (glycerine), used as a stabiliser and tonicity agent.
Phenol, a preservative.
Sodium hydroxide solution and concentrated hydrochloric acid, for pH adjustment.
Water for injection, serving as the solvent and base of the solution.

Administration and Dosage Schedule for Mounjaro Injections

Treatment typically begins with a once-weekly dose of 2.5 mg for the first four weeks to help reduce gastrointestinal side effects. The dose is then increased once weekly to achieve the standard maintenance dose – Mounjaro 5mg.

If additional glycaemic control or weight loss is needed, the Mounjaro doses may be increased in 2.5 mg steps every four weeks, up to a maximum of 15 mg weekly, depending on individual response and tolerability.

Where to inject Mounjaro and when?

Mounjaro should be injected into the abdomen, thigh, or upper arm. Rotating sites is necessary to prevent possible skin issues.

The drug can be taken with or without food. To maintain consistent drug levels and minimise side effects, it is recommended to inject Mounjaro on the same day each week. Each pen is single-use and should be disposed of after injection.

Common and Rare Side Effects of Mounjaro

Like many medications, Mounjaro may cause side effects. Most are mild to moderate and gastrointestinal in nature, but some may require medical attention.

Common side effects occur in more than 1 in 10 people, with nausea being the most frequently reported, affecting up to 22% of patients. Diarrhoea, vomiting, and constipation are also frequently reported, each affecting more than 10% of users. Other common effects include decreased appetite, indigestion, abdominal pain, belching, flatulence, and heartburn.

Less frequent side effects, reported by 1% to 10% of patients, include:

Injection site reactions.
Hypersensitivity reactions such as rash, itching, or eczema.
Dizziness, fatigue, hair loss, bloating, stomach pain, and low blood pressure.
Increased pancreatic enzymes.

Serious side effects are relatively rare, affecting fewer than 1 in 100 people, but may still occur:

Acute kidney injury, often related to dehydration from gastrointestinal symptoms.
Pancreatitis.
Worsening diabetic retinopathy, particularly in those with pre-existing eye disease.
Gastroparesis (delayed stomach emptying).
Gallbladder disease, including gallstones and inflammation.
Hypoglycaemia, especially when used with insulin or sulfonylureas.
Severe allergic reactions, including anaphylaxis.

These are possible Mounjaro side effects for non-diabetics and diabetics, although the risks may vary for these groups of users.

Lifestyle Changes for Improving Mounjaro Treatment Results

Combining Mounjaro with thoughtful lifestyle and dietary changes is key to achieving the best results and minimising side effects. Without these adjustments, some gastrointestinal side effects may become too uncomfortable, especially during the first weeks of the therapy, and lead to the treatment discontinuation.

What to eat on Mounjaro:

Lean protein with every meal as it helps preserve muscle mass, supports metabolism, and increase the feeling of fullness.
Non-starchy vegetables and fruits to increase fibre for better digestion and satiety, while providing essential vitamins and antioxidants
Whole grains like oats, brown rice, and whole wheat pasta instead of refined carbohydrates to support gut health and stable energy.
Healthy fats in moderation, including olive oil, avocado, and nuts as they provide essential fatty acids, aid nutrient absorption and reduce inflammation.

Drinking water consistently throughout the day is essential to stay hydrated and ease nausea. Eating smaller, more frequent meals also supports appetite control and reduces digestive discomfort. A high-quality probiotic containing Lactobacillus and Bifidobacterium strains can further support digestion, relieve constipation, and help maintain a healthy microbiome.

For effective treatment with Mounjaro, consistency is essential. Maintaining the therapy alongside stable lifestyle and dietary habits supports the body’s ability to adapt, respond, and achieve optimal results.

Learn more about Forte80™

This article has been written with information taken from supported scientific research, and its purpose is purely educational. It should not be intended as medical advice or be used in personal diagnoses. Individuals on GLP-1 weight loss drugs should work closely with healthcare providers to develop a comprehensive, holistic health plan. With proper support, including targeted supplementation for digestive health, many more people may be able to benefit from these groundbreaking medications without sacrificing comfort or quality of life.

References:

What is Mounjaro? The Unique GLP-1 and GIP Drug for Type 2 Diabetes

What Is Mounjaro and How Does It Work?