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  • Josie Barnes

Mounjaro for Weight Loss and Zepbound side effects

Updated: Apr 22

Mounjaro and Zepbound

In this article, we are talking about Mounjaro (or Zepbound). We will discuss what it is, how it works, possible side effects, alternatives to Mounjaro, and more!

Here's the links to the relevant sections:

The above video is a must watch before considering Mounjaro/Zepbound or other weight loss injections.

What is Mounjaro?

Mounjaro: A Novel Dual GIP/GLP-1 Receptor Agonist for Type 2 Diabetes

Mounjaro (with the active ingredient tirzepatide) is a prescription medication available in various dosage strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg per 0.5 mL injection. It is indicated for adults with type 2 diabetes to improve blood sugar (glucose) control when used in conjunction with diet and exercise.

Zepbound and Mounjaro are basically the same drug, but they’re approved for different reasons/medical conditions: Zepbound for weight loss and Mounjaro for diabetes. Having said that, they both contain the same active ingredient.

Mounjaro's mechanism of action differs from existing diabetes medications. It is a single molecule designed to bind to and activate both glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors. This dual agonistic action sets Mounjaro apart from other therapies and potentially offers enhanced therapeutic benefits for managing type 2 diabetes.

Clinical studies have demonstrated Mounjaro's superior efficacy in lowering blood sugar levels, promoting weight loss, and improving cardiovascular risk factors compared to other diabetes medications. Additionally, Mounjaro has demonstrated a favourable safety profile.

Key Points about Mounjaro/Zepbound:

  • A novel dual GIP/GLP-1 receptor agonist for type 2 diabetes

  • Available in various dosage strengths to personalise treatment

  • Works differently than existing diabetes medications by activating both GIP and GLP-1 pathways

  • Demonstrated superior efficacy in lowering blood sugar levels, promoting weight loss, and improving cardiovascular risk factors

  • Exhibits a favourable safety profile

Important Considerations:

  • Not recommended for individuals with a history of pancreatitis or type 1 diabetes

  • Safety and efficacy in children under 18 have not been established

Mounjaro represents a significant advancement in the treatment of type 2 diabetes, offering a new therapeutic option with the potential to improve glycemic control and overall health outcomes for patients worldwide.

It is a TGA approved treatment for diabetes (and has FDA approval) and is manufactured by Eli Lilly.

What's the difference between Mounjaro and Zepbound?

Mounjaro and Zepbound are the same drug. Zepbound and Mounjaro are the exact same medication, with the active ingredient tirzepatide. Zepbound and Mounjaro are basically the same drug as they contain the same active ingredient, but they’re approved for different reasons/medical conditions: Zepbound is given specifically for weight loss and Mounjaro for diabetes management. But, they both contain the same active ingredient.

Precisely why Eli Lilly opted for the name Zepbound remains shrouded in secrecy, as the company has refrained from divulging details about the naming process. However, experts in the pharmaceutical industry have suggested that the drug's name offers valuable insights into the marketing disparities between the United States and Europe, as well as the challenges associated with crafting a memorable and evocative brand identity.

It is not known whether the name change was anything to do with a woman who died taking injectable weight loss drugs.

How Mounjaro works

Mounjaro (tirzepatide) has emerged as a groundbreaking dual agonist, offering a unique approach to regulating blood sugar levels and promoting weight loss. Its mechanism of action, distinct from conventional therapies, has captivated the scientific community and holds immense promise for improving the lives of millions worldwide.

The Science Behind Mounjaro/Zepbound's Dual Agonism

Mounjaro/Zepbound's therapeutic power stems from its ability to simultaneously activate two key incretin hormones: glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). These hormones play a crucial role in regulating blood sugar levels and influencing appetite.

GIP stimulates insulin secretion from the pancreas, the organ responsible for producing insulin, the hormone that regulates blood sugar levels. It also enhances glucose uptake by cells, effectively removing excess sugar from the bloodstream.

GLP-1, on the other hand, inhibits glucagon production, a hormone that raises blood sugar levels. Additionally, it slows gastric emptying, the process by which food leaves the stomach, promoting a feeling of fullness and reducing appetite.

The Therapeutic Benefits of Dual Agonism

By targeting both GIP and GLP-1 receptors, Mounjaro/Zepbound exhibits a synergistic effect, amplifying the benefits of each individual hormone. This dual agonistic action translates into enhanced blood sugar control, increased weight loss, and improved cardiovascular risk factors.

Blood Sugar Control: Mounjaro/Zepbound effectively lowers blood sugar levels by stimulating insulin secretion and reducing glucagon production. This dual action helps maintain glycemic control, a critical aspect of diabetes management.

Weight Loss: Mounjaro/Zepbound's ability to slow gastric emptying and promote satiety leads to significant weight loss. Studies have demonstrated that Mounjaro/Zepbound can induce clinically meaningful weight loss, surpassing the efficacy of other weight management medications.

Cardiovascular Risk Factors: Mounjaro/Zepbound has also shown promise in improving cardiovascular risk factors, including lowering blood pressure, reducing LDL (bad) cholesterol, and increasing HDL (good) cholesterol.

Mounjaro/Zepbound: Hope for Diabetes and Obesity

The emergence of Mounjaro/Zepbound represents a significant leap forward in the treatment of type 2 diabetes and obesity. Its unique dual agonistic mechanism of action offers enhanced therapeutic benefits, providing a promising new option for patients seeking effective blood sugar control and weight management. As research continues to unveil the full potential of Mounjaro/Zepbound, its impact on improving the lives of those affected by diabetes and obesity is poised to be profound.

Side effects of Mounjaro

The most common side effects of Mounjaro/Zepbound include:

  • Nausea

  • Vomiting

  • Diarrhoea

  • Abdominal pain

  • Constipation

  • Fatigue

  • Injection site reactions (pain, redness, swelling)

These side effects are typically mild and temporary, and they often improve as the body adjusts to the medication.

Serious Side Effects

Zepbound and Mounjaro can also cause serious side effects, but these are less common. These serious side effects include:

  • Pancreatitis: Zepbound can increase the risk of pancreatitis, an inflammation of the pancreas. Symptoms of pancreatitis include upper abdominal pain, nausea, vomiting, and loss of appetite.

  • Gallbladder problems: Zepbound can increase the risk of gallbladder problems, such as gallstones. Symptoms of gallbladder problems include upper abdominal pain, nausea, vomiting, and jaundice (yellowing of the skin and eyes).

  • Allergic reactions: Zepbound can cause serious allergic reactions, including anaphylaxis. Symptoms of an allergic reaction can include rash, hives, swelling of the face, throat, or tongue, difficulty breathing, and dizziness.

Other Potential Side Effects

Zepbound may also cause other side effects, including:

  • Low blood sugar levels

  • Dehydration

  • Changes in appetite

  • Changes in heart rate

  • Changes in blood pressure

  • Hair loss

Seek Medical Attention

If you experience any side effects while taking Zepbound, be sure to tell your doctor. This is especially important if you experience any of the serious side effects listed above. Always be on the watch out for possible symptoms of a reaction to taking any new drug.

Important Considerations

  • Mounjaro is not recommended for individuals with a history of pancreatitis or type 1 diabetes.

  • The safety and efficacy of Mounjaro and Zepbound in children under 18 have not been established.

It is important to note that this is not a complete list of all possible side effects of Zepbound. For more information, please refer to the Zepbound Product Information. Long-terms use of Mounjaro or Zepbound can't really be assessed yet as it is a relatively new weight loss drug.

In addition to the above side effects, there is a link between Mounjaro/Zepbound and thyroid cancer (medullary thyroid carcinoma). Serious side effects are not common with Zepbound and if your GO prescribes the medication, you should be fine although always watch out for side effects when taking new medication and immediately seek medical advice or medical help if you have any serious allergic reactions.

What is the recommended dose of Mounjaro?

Put simply, the recommended dose of Mounjaro/Zepbound is what you Doctor, GP or Healthcare Provider tells you. However, there are guidelines from the manufacturer after clinical trials. These are usually the doses that the Doctor's will prescribe.

Mounjaro and Zepbound Dosage Guidelines:

  1. Starting Dose: Initiate treatment with tirzepatide 2.5 mg once weekly.

  2. Initial Dose Escalation: After four weeks on the starting dose, increase the dosage to tirzepatide 5 mg once weekly.

  3. Further Dose Adjustments: Subsequent dose increases can be made in 2.5 mg increments at intervals of no less than four weeks on the current dose.

  4. Recommended Maintenance Doses: The recommended maintenance doses for tirzepatide are 5 mg, 10 mg, and 15 mg once weekly. The 2.5 mg, 7.5 mg, and 12.5 mg doses are not considered maintenance doses.

  5. Maximum Dose: The maximum recommended dose of tirzepatide is 15 mg once weekly.

  6. Additional Information: For detailed prescribing information, please refer to the Mounjaro (tirzepatide) Product Information.

​Mounjaro or Zepbound is given as a once-weekly injection and can assist with chronic weight management.

Where to buy Mounjaro/Zepbound?

Mounjaro and Zepbound are only available via a prescription. You cannot get them over the counter at your local pharmacy so you need to make an appointment and visit your Healthcare Provider to see if these weight loss injections are suitable for you.

There are many diabetes medicines out there that can assist with achieving an ideal body weight and Mounjaro (or Zepbound as it is being called) is just one of them. So you cannot just 'buy' Zepbound or Mounjaro,. You need a proper physical assessment from your Doctor who will take into account any medical conditions you may have, such as high blood pressure, high blood sugar levels, fast heartbeat etc.

If you are concerned about possible side effects of Mounjaro, there are alternatives available that do not require a visit to the GP nor do they require an injection every week. Prescription drugs can be very effective for diabetes management and weight loss, but they are not for everyone.

Alternatives to Mounjaro

Having a weekly injection isn't the nicest of things and Mounjaro/Zepbound can prove to be very expensive. However, there are alternatives to prescription medicines that can work very well.

Weight loss medications or diabetes treatments don't have to come via prescription - there are other recommended weight loss supplements that get extremely positive reviews from people in the US and Australia, they are less expensive, and don't involve needles. There are also more on the Editor's Choice page.

More information

​Ozempic is another common injectable medication for people with diabetes mellitus. It works differently to Mounjaro and could be more suitable depending on what advice you get from your healthcare provider.

Additional information about Zepbound (remember, Zepbound and Mounjaro are the same thing).

Zepbound: A Novel Dual GIP/GLP-1 Receptor Agonist for Weight Management

Zepbound (tirzepatide) is a recently FDA-approved medication for chronic weight management in adults with obesity or overweight with at least one weight-related condition. It belongs to a class of medications called dual agonists, targeting two hormones involved in regulating appetite and energy balance: glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP).

Distinctive Features of Zepbound

Zepbound's unique dual agonistic mechanism of action sets it apart from other weight management medications. By simultaneously activating both GLP-1 and GIP receptors, Zepbound exerts a synergistic effect, amplifying the benefits of each hormone. This translates into enhanced weight loss efficacy and improved overall metabolic health.

Clinical Efficacy of Zepbound

Clinical trials have demonstrated Zepbound's remarkable ability to induce significant and sustained weight loss. In one study, participants receiving Zepbound achieved a 22.5% reduction in body weight over 72 weeks, significantly exceeding the weight loss observed with other GLP-1 receptor agonists like semaglutide (Wegovy).

Eligibility for Zepbound

Zepbound is indicated for adults with obesity (body mass index [BMI] ≥ 30) or overweight (BMI ≥ 27) with at least one weight-related condition, such as type 2 diabetes, high blood pressure, or high cholesterol. However, it is important to note that Zepbound is not a standalone treatment for weight management. It should be used in conjunction with a reduced-calorie diet and increased physical activity for optimal results.

Potential Side Effects

Like other medications, Zepbound can cause side effects, including diarrhoea, nausea, vomiting, constipation, abdominal discomfort, injection site reactions, fatigue, allergic reactions, burping, hair loss, and gastroesophageal reflux disease.

Considerations for Zepbound Use

Zepbound may not be suitable for everyone. Individuals with a fear of needles, those not committed to long-term medical management, those with a history of pancreatitis or at risk of pancreatitis, and those with gastroparesis should discuss alternative weight management options with their healthcare provider. If you are concerned about the drug administration and if weight loss injections may not be your cup of tea, there are alternatives for diabetes management and weight loss available (that don't require a prescription).


Zepbound represents a significant advancement in the treatment of obesity, offering a promising new therapeutic option for individuals seeking effective and sustained weight loss. Its unique dual agonistic mechanism of action and demonstrated clinical efficacy make it a valuable tool in the fight against obesity. Remember, only health care providers can give you prescription medications.

Eli Lilly and Novo Nordisk competition

The obesity market has witnessed a significant shift with the recent FDA approval of Eli Lilly's Zepbound (tirzepatide), a GLP-1/GIP dual agonist, challenging Novo Nordisk's dominance with its GLP-1 agonist Wegovy (semaglutide). Zepbound's anticipated superior efficacy, attributed to its dual agonist properties, poses a threat to Wegovy's market share.

Novo Nordisk, in response, has launched a new Phase III trial to compare the efficacy and safety of the maximum dose of Zepbound against its late-stage therapy CagriSema, a fixed-dose combination of semaglutide and cagrilintide. Cagrilintide, a long-acting amylin analogue, aims to potentiate semaglutide's weight loss effects.

Phase II trial results suggest that CagriSema may induce greater weight loss than the highest dose of Zepbound in a shorter timeframe. This potential superiority could position CagriSema as a formidable competitor to Zepbound once it reaches the market.

With the entry of Zepbound, Novo Nordisk faces potential erosion of its market share currently held by Wegovy. To counter this challenge, Novo Nordisk is actively advancing its pipeline drugs for type 2 diabetes and/or obesity, including the ongoing comparative Phase III trial against Zepbound. The aim is to establish the superiority of CagriSema and solidify its position in the obesity treatment landscape.

The intensifying competition between Eli Lilly and Novo Nordisk is expected to drive innovation and lead to the development of even more effective and patient-centric treatment options for obesity and weight loss treatment.

Eli Lilly Builds New Manufacturing Facility to Keep up with Demand

Eli Lilly Invests $2.5 Billion to Expand Manufacturing Capacity for In-Demand Diabetes and Obesity Treatments

Eli Lilly and Company is making a significant investment in its manufacturing capabilities to meet the growing demand for its diabetes and obesity medications. The company is allocating $2.5 billion to construct a new state-of-the-art facility in Rhineland-Palatinate, Germany, dedicated to the production of injectable drugs and devices, including its blockbuster diabetes treatment Mounjaro and the recently FDA-approved weight-loss drug Zepbound.

This strategic investment reflects the surging demand for GLP-1 receptor agonists, a class of medications that have revolutionised the treatment of type 2 diabetes and obesity. Eli Lilly, along with its main competitor Novo Nordisk, has faced challenges in keeping up with the rapid uptake of these therapies, leading to supply shortages and limited access for patients.

The new manufacturing plant, expected to be operational in 2027, will significantly boost Eli Lilly's production capacity, ensuring a steady supply of its injectable medications to meet patient needs. The facility will employ approximately 1,900 people during the construction phase and 1,000 skilled workers once fully operational.

Eli Lilly's CEO, David Ricks, has underscored the company's commitment to addressing supply constraints and ensuring patients have access to its life-changing therapies. He emphasizes that the company is taking an "all hands on deck" approach to tackle supply challenges and ensure a smooth rollout of its new weight-loss drug, Zepbound.

The investment in the new manufacturing plant is a testament to Eli Lilly's dedication to innovation and patient care. By expanding its production capabilities, the company is well-positioned to meet the growing demand for its injectable drugs and devices, ensuring that patients with diabetes and obesity have access to the treatments they need to improve their health and well-being.


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