Is Mounjaro Safe?

Mounjaro (tirzepatide) has quickly gained popularity as a groundbreaking medication for weight loss. Why is it so popular? Because it works! Mounjaro is Manufactured by Eli Lilly and it works by mimicking two natural gut hormones—glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). This combination of hormones allows Mounjaro to reduce appetite, increase satiety, and help control blood sugar levels. Is Mounjaro safe? This is the question that naturally arises if you are considering using Mounjaro long-term for weight loss. This is what this blog will attempt to address.

In this blog we will explore how safe Mounjaro is, the risks and the benefits. To start the blog we will briefly discuss Mounjaro, itself, what it is, how effective it is,  and the circumstances under which it may not be suitable. By the end, you’ll have a comprehensive understanding of  Mounjaro’s safety and whether it may be right for you.

Please use the navigational table to skip to topics of interest.

What Is Mounjaro?

Mounjaro contains the active ingredient tirzepatide, which is a dual GLP-1 and GIP receptor agonist. GLP-1 and GIP are both incretin hormones that help regulate insulin secretion, control blood sugar levels, and suppress appetite. Because Mounjaro combines both of these incretins, it is called a “twincretin”.

By mimicking these hormones, Mounjaro works on two fronts: it helps lower blood glucose levels in people with type 2 diabetes and helps with weight loss by reducing hunger and promoting feelings of fullness.

Incretins like GLP-1 and GIP aid in weight loss by:

• Suppressing appetite
• Increasing feelings of fullness (satiety)
• Slowing gastric emptying

Early studies on diet-induced obese (DIO) mice demonstrated that combining GLP-1 and GIP resulted in significantly greater weight loss. Recognising its promising potential, Eli Lilly patented tirzepatide in 2016 and subsequently confirmed its effectiveness for weight loss in humans in the SURMOUNT trials.

How effective is Mounjaro for weight loss?

Mounjaro is administered via a weekly injection, and it has been shown to be highly effective in clinical trials. The SURMOUNT 1 trial demonstrated that Mounjaro could lead to an average weight loss of 22.5% over 72 weeks for individuals with obesity but who were not diabetic when used at the highest maintenance dose (15mg)

Kilogrammes (kgs) Pounds (lbs)

Week	Tirzepatide (5mg)	Tirzepatide(10mg)	Tirzepatide (15mg)	Placebo
0	105 kg	105 kg	105 kg	105 kg
4	101 kg	100.5 kg	100 kg	104.5 kg
8	96.5 kg	95.5 kg	95 kg	104 kg
12	93.5 kg	91.5 kg	90 kg	103.5 kg
16	91.5 kg	89 kg	87 kg	103 kg
24	90 kg	86 kg	84.5 kg	102.5 kg
36	89.3 kg	84.5 kg	83 kg	102.4 kg
48	89 kg	83.5 kg	82 kg	102.4 kg
72	88.6 kg	82.6 kg	81.2 kg	102.4 kg

The benefits of Mounjaro

https://medicalmojo.co.uk/product/mounjaro-2-5mg-injection/It is always best to deliver good news before bad so before we address the safety concerns of Mounjaro, let’s highlight its benefits.

1. Effective weight loss: Mounjaro has been shown to help individuals lose substantial amounts of weight, with some people losing up to 23.8 kg (52.5 lbs) after 72 weeks of treatment at the 15mg dose. This makes it an attractive option for people struggling with obesity or those who have not had success with other weight loss treatments.
2. Improved blood sugar control: For individuals with type 2 diabetes, Mounjaro can help regulate blood glucose levels. By increasing insulin secretion and reducing the amount of glucose produced by the liver, Mounjaro helps to bring blood sugar levels under control.

The SURPASS-1 trial demonstrated that tirzepatide or Mounjaro significantly improved participants’ blood sugar control compared to a placebo.

31–52% of participants reached normal blood sugar levels (HbA1c <5.7%), and importantly, there was no increased risk of severe low blood sugar (hypoglycaemia).

• Reduced appetite: One of the most well-known benefits of Mounjaro is its ability to reduce appetite. This makes it easier for individuals to adhere to a calorie-restricted diet and achieve weight loss, especially since appetite control is one of the hardest aspects of long-term weight management.

4. Dual Action: Mounjaro is a “twincretin” medication, that combines the effects of GLP-1 and GIP, which makes it more effective in promoting greater weight loss compared to medications that only target GLP-1 receptors.

The SURMOUNT-5 trial was the first to directly compare Mounjaro (tirzepatide) and Wegovy (semaglutide) and found that participants on Zepbound (Mounjaro’s name in the US), lost an average of 20.2% of their body weight over 72 weeks compared to 13.7% lost with Wegovy.

The safety profile of Mounjaro

While Mounjaro offers significant benefits, like any medication, it may not be suitable for everyone and is associated with a number of side effects.

Understanding the safety profile of Mounjaro requires examining its most common, uncommon, and serious side effects, as well as the populations for whom it may not be recommended.

The SURMOUNT 1 trial looked at the results of Mounjaro as a potential weight loss drug. It was a large-scale phase 3 clinical trial with a total of 2,539 participants.

In addition to discovering the huge potential of Mounjaro as a weight loss drug, it could lead to an average weight loss of 22.5% over 72 weeks it also revealed the extent of the side effects associated with it.

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Mounjaro side effects

The following table is taken from the results of the SURMOUNT 1 trial, the figures indicate the percentage of participants who experienced side effects when taking Mounjaro or the placebo.

The following table is taken from the results of the SURMOUNT 1 trial, the figures indicate the percentage of participants who experienced the side effects.

Side effect	Tirzepatide 5mg	Tirzepatide 10mg	Tirzepatide 15mg	Placebo
Nausea	24.6	33.3	31	9.5
Diarrhoea	18.7	21.2	23	7.3
Constipation	16.8	17.1	11.7	5.8
Dyspepsia or indigestion	8.9	9.7	11.3	4.2
Vomiting	8.3	10.7	12.2	1.7
Headache	6.5	6.8	6.5	6.5
Abdominal pain	4.9	5.3	4.9	3.3
Alopecia or hair loss	5.1	4.9	5.7	0.9
Dizziness	4.1	5.5	4	2.3
Eructation or burping	3.8	5.2	5.6	0.6

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Week	Tirzepatide (5mg)	Tirzepatide(10mg)	Tirzepatide (15mg)	Placebo
0	231 lbs	231 lbs	231 lbs	231 lbs
4	222.2 lbs	221.3 lbs	220.5 lbs	230 lbs
8	212.7 lbs	210.5 lbs	209.4 lbs	229 lbs
12	206 lbs	201.6 lbs	198.4 lbs	228 lbs
16	201.6 lbs	196.2 lbs	191.8 lbs	227 lbs
24	198.4 lbs	189.6 lbs	186.2 lbs	226 lbs
36	196.8 lbs	186.3 lbs	183 lbs	225.8 lbs
48	196.2 lbs	184 lbs	180.7 lbs	225.8 lbs
72	195.3 lbs	182.1 lbs	179 lbs	225.8 lbs

Very common side effects of Mounjaro

These common side effects of Mounjaro may affect more than 1 in 10 people:

• Nausea
• Vomiting
• Diarrhoea
• Constipation

These effects are generally mild and tend to occur when you first start Mounjaro, especially during the dose escalation period as your body adjusts to the medication. In most cases, they decrease over time. However, if these side effects become severe, you should contact your doctor immediately.

Common side effects of Mounjaro

Mounjaro’s common side effects may affect up to 1 in 10 people and include:

• Allergic reactions (hypersensitivity), such as rash, itching, or eczema
• Dizziness, reported by some patients using it for weight management
• Low blood pressure observed in some patients
• Abdominal pain
• Indigestion (dyspepsia)
• Stomach bloating
• Burping (eructation)
• Gas (flatulence)
• Reflux or heartburn (gastroesophageal reflux disease – GERD), where stomach acid moves up into the oesophagus
• Hair loss, which has been seen in patients using the medication for weight management
• Fatigue (tiredness)
• Injection site reactions, like redness or itching

These side effects are generally mild and usually improve over time. However, if they persist or worsen, you should contact your doctor.

Uncommon side effects of Mounjaro

Mounjaro’s uncommon side effects affect up to 1 in 100 people and include:

• Changed sense of taste: Some people may notice that food tastes different while using Mounjaro, which can reduce appetite or make eating less enjoyable. This usually improves over time as your body adjusts to the medication.
• Increased heart rate: Some people may experience a faster heart rate or pulse, though this is more commonly seen with doses used for diabetes treatment rather than weight management.
• Elevated pancreatic enzymes: An increase in certain pancreatic enzymes, such as amylase, can be detected in the blood. This could indicate a problem with the pancreas.
• Gallstones: Gallstones are hardened deposits of bile that form in the gallbladder. They can be silent until they block the bile ducts, causing intense pain in the stomach, which may last from a few minutes to hours and may be accompanied by confusion, fever, and chills. If you experience sudden, severe stomach pain, especially after eating fatty foods, contact your doctor.
• Injection site pain: You may feel discomfort, soreness, redness, or swelling where the injection is given. To reduce pain, try rotating the injection site or applying ice before injecting.
• Increased calcitonin levels: Some people may have elevated levels of calcitonin, a hormone that helps regulate calcium in the blood.
• Cholecystitis (Gallbladder Infection): This is an infection or inflammation of the gallbladder, which is located near your liver. Symptoms include sudden, sharp pain in the upper right side of the stomach, fever, and jaundice (yellowing of the skin or eyes). If you experience these symptoms, seek immediate medical attention as this condition may require hospital treatment.

These side effects are uncommon but can be serious. If you experience any of these symptoms, contact your doctor right away. If you suspect gallstones or cholecystitis and can’t reach your doctor, call 111 or go to the nearest A&E, as these conditions may need urgent treatment.

Serious side effects of Mounjaro

Fortunately, serious side effects of Mounjaro are uncommon and rare.

Uncommon serious side effects
These may affect up to 1 in 100 people and include:

• Acute pancreatitis: This is inflammation of the pancreas, which can cause severe and persistent stomach and back pain. If you experience intense pain in these areas, it is crucial to seek medical attention immediately.

If you suspect you have acute pancreatitis, contact your doctor right away or go to A&E for treatment.

Rare serious side effects
These may affect up to 1 in 1,000 people and include:

• Severe allergic reaction (Anaphylaxis or angioedema): This reaction can cause difficulty breathing, swelling of the face or lips, and trouble swallowing. It is a medical emergency.

A severe allergic reaction requires immediate attention. Call 999 or go to A&E immediately, bringing your medication packet with you and informing healthcare providers that you are taking Mounjaro.

Managing Mounjaro side effects

Most of the side effects associated with Mounjaro are generally mild and decrease over time and more commonly occur during the dose escalation period.

For a full review of how to manage these side effects, please refer to our blog, Mounjaro Side Effects.

Who should avoid Mounjaro?

Not everyone should take Mounjaro. Individuals with certain health conditions may need to avoid the medication, including those with:

• A history of pancreatitis: Individuals who have had pancreatitis in the past or who have chronic pancreatitis should not take Mounjaro, as it may increase the risk of acute pancreatitis.
• Severe gastrointestinal problems: Mounjaro may worsen conditions like severe gastroparesis, a disorder that affects the stomach’s ability to empty its contents.
• Allergy to tirzepatide: If you have an allergy to tirzepatide or any of the ingredients in Mounjaro, you should avoid using this medication.
• Pregnancy and breastfeeding: Mounjaro is not recommended for use during pregnancy or breastfeeding due to the lack of safety data.

Individuals with kidney or liver problems, or certain eye conditions like diabetic retinopathy, should also exercise caution and consult their doctor before starting Mounjaro.

Mounjaro and thyroid cancer

Before we finish discussing Mounjaro’s safety profile, let’s briefly talk about its possible link to cancer. For a more in-depth discussion, check out our blog, “Does Mounjaro cause thyroid cancer?”

Concerns about Mounjaro and thyroid cancer came from animal studies, where high doses of GLP-1 drugs like Mounjaro caused thyroid tumours in rodents. However, humans and primates have very few or no GLP-1 receptors on thyroid cells, which means the risks seen in animals might not apply to people.

A large study published in  BMJ on April 10, 2024, followed over 145,000 people using GLP-1 medications, including Mounjaro, for nearly 4 years.

The study found no significant increase in thyroid cancer risk compared to people taking other diabetes medications. The researchers concluded that GLP-1 medications, like Mounjaro, do not significantly raise the risk of thyroid cancer, with any possible risk being very small. This gives reassurance that Mounjaro is unlikely to cause thyroid cancer in humans.

What should you do if you are concerned about Mounjaro and the risk of cancer?

If you’re using Mounjaro or similar medications, here’s what to keep in mind:

• Follow your treatment plan: For most people, the benefits of Mounjaro in managing diabetes and helping with weight loss outweigh any potential risks.
• Talk to your doctor: If you or your family have a history of thyroid cancer (MTC) or other related conditions, let your healthcare provider know before starting or continuing treatment.
• Watch for warning signs: Keep an eye out for symptoms like lumps in your neck or trouble swallowing, and contact your doctor if you notice any of these.

Long-term safety of Mounjaro

The SURPASS-4 trial assessed the long-term safety and efficacy of Mounjaro (tirzepatide) in patients with type 2 diabetes.

Tirzepatide was generally well tolerated across all five SURPASS trials. The most common side effects related to the digestive system were nausea, vomiting, and diarrhoea.

Concerns with low blood sugar or hypoglycaemia, occurred when Mounjaro was used in those diabetic patients taking sulfonylureas or insulin.

Conclusion: Is Mounjaro safe?

Studies on the long-term safety of Mounjaro, particularly with the highest maintenance dose of 15mg, have shown that the medication does not present any significant long-term health risks.

However, patients should be monitored for potential side effects like pancreatitis or severe dehydration, which, if left untreated, can lead to long-term health complications.

Mounjaro is considered to be a safe and effective medication for weight loss and while it is not without its risks, most side effects are mild and temporary.

The benefits of Mounjaro, including substantial weight loss and improved diabetes management, make it a valuable option for many patients.

To learn if Mounjaro is suitable for you, contact us for a FREE Mounjaro weight-loss consultation.

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Frequently asked questions about Mounjaro

Can I drink alcohol while using Mounjaro?

It’s best to limit alcohol while taking Mounjaro, as alcohol can increase the risk of side effects like nausea and dizziness. For more information, check out our blog, “Can you drink alcohol while taking Mounjaro?”

Can I take Mounjaro with levothyroxine?

There are no confirmed interactions between Mounjaro and levothyroxine, but it’s important to keep an eye on your thyroid levels. For more details, visit our blog, “Can I take Mounjaro with levothyroxine?”

Does Mounjaro cause thyroid cancer?

While there were concerns in early studies with rodents, there’s little evidence to suggest Mounjaro causes thyroid cancer in humans. For further details, see our blog, “Does Mounjaro cause thyroid cancer?”

How much weight can I lose with Mounjaro?

The SURMOUNT 1 trial found the following weight loss with Mounjaro:

• 5mg: 16.4 kg (36.1 lbs)
• 10mg: 22.4 kg (49.4 lbs)
• 15mg: 23.8 kg (52.5 lbs)

Does Mounjaro help with sleep apnoea?

Studies suggest Mounjaro may help improve sleep apnoea symptoms. For more details, visit our blog,  “Mounjaro and sleep apnoea.”

Does Mounjaro cause hair loss?

Mounjaro has been linked to hair loss in about 5% of users, although it’s unclear whether this is due to the medication or rapid weight loss. For more information, check out our blog,  “Does Mounjaro cause hair loss?”

How long do the side effects of Mounjaro last?

Side effects like nausea, bloating, and constipation are typically temporary and improve after a few days or weeks as your body adjusts. For more details, visit our blog, “How long do the side effects of Mounjaro last?” and to learn more about Mounjaro’s side effects and how to manage them, have a read of Mounjaro side effects.

Should I stop taking Mounjaro once I’ve reached my target weight?

Stopping Mounjaro after reaching your target weight may make it harder to maintain your weight loss and could lead to regaining weight due to increased appetite and unhealthy eating habits.

Can I start Mounjaro at 5 mg?

No, the starting dose of Mounjaro is 2.5 mg. Following the prescribed dosing schedule is important to minimise side effects and help your body adjust.

Can I stay on 2.5 mg of Mounjaro?

Staying on Mounjaro 2.5 mg long-term is generally not recommended. After about 4 weeks, the dose should be increased to Mounjaro 5 mg. If you experience severe side effects, contact us to discuss alternatives or adjustments.

Can you lose weight on 2.5 mg of Mounjaro?

Some weight loss may occur at Mounjaro 2.5 mg, but more significant results are typically seen with higher doses.

When do you move from 2.5 mg to 5 mg of Mounjaro?

After 4 weeks on Mounjaro 2.5 mg, you will typically increase to Mounjaro 5 mg. If you experience any side effects, consult us to discuss how to proceed with your dosage.

Can you take Mounjaro every 10 days?

No, Mounjaro should be taken weekly, at the same time and on the same day each week. Taking it every 10 days could result in hunger between doses. You can stay on a lower maintenance dose while keeping the weekly schedule.

Which maintenance dose of Mounjaro produces the most weight loss?

The SURMOUNT 1 trial showed that the most weight loss occurred with the 15mg dose (23.8 kg over 72 weeks), followed by 10mg (22.4 kg) and 5mg (16.4 kg).

Achieving weight loss with Mounjaro and personalised support

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Medical Mojo’s customised weight loss program

At Medical Mojo, we offer personalised weight loss coaching to help you achieve your goals. Our program includes:

• Weekly check-ins to track progress and stay motivated
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Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice.

References:

• BMJ. (2024). Glucagon-like peptide 1 receptor agonist use and risk of thyroid cancer: Scandinavian cohort study. BMJ, 385, e078225. https://doi.org/10.1136/bmj-2023-078225 (Published 10 April 2024).
• Bokvist, K.B., Finan, B., Friedrichsen, S., & Heise, T. (2016). Glucagon-like peptide-1 receptor (GLP-1R) agonists combined with glucose-dependent insulinotropic peptide (GIP) receptor agonists for the treatment of metabolic disorders. United States Patent US9474780B2. Retrieved from https://patents.google.com/patent/US9474780/en.
• ClinicalTrials.gov. (2023). SURPASS-4: A phase 3 trial assessing the long-term safety and efficacy of tirzepatide in patients with type 2 diabetes. Retrieved from https://clinicaltrials.gov/study/NCT03730662?tab=results
• ClinicalTrials.gov. (2023). SURPASS-5: A phase 3 trial of tirzepatide for weight management in adults with obesity or overweight with weight-related comorbidities. Retrieved from https://clinicaltrials.gov/study/NCT04039503
• ClinicalTrials.gov. (2021). SURMOUNT-1: Tirzepatide for Weight Loss in Non-Diabetic Obese Individuals. Retrieved from https://clinicaltrials.gov.
• ClinicalTrials.gov. (2023). Study of Tirzepatide (Mounjaro) in Overweight or Obese Participants with Weight-related Comorbidities (SURMOUNT-5). Retrieved from https://clinicaltrials.gov/study/NCT05822830
• Coskun, T., et al. (2018). Tirzepatide, a dual GLP-1 and GIP receptor agonist, induces significant weight loss in patients with obesity. Diabetes Care, 41(10), 2100–2108.
• Eli Lilly and Company. (2021). Mounjaro (tirzepatide) 2.5 mg, 5 mg, 10 mg, and 15 mg solution for injection in pre-filled pen: Patient information leaflet. Retrieved from https://www.medicines.org.uk/emc/files/pil.15481.pdf
• Garvey, W.T., Frias, J.P., Jastreboff, A.M., le Roux, C.W., Sattar, N., Aizenberg, D., Mao, H., Zhang, S., Ahmad, N.N., Bunck, M.C. and Benabbad, I., 2023. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2): a double-blind, randomised, multicentre, placebo-controlled, phase 3 trial. The Lancet, 402(10402), pp.613-626.
• Jastreboff, A.M., Aronne, L.J., Ahmad, N.N., Wharton, S., Connery, L., Alves, B., Kiyosue, A., Zhang, S., Liu, B., Bunck, M.C. and Stefanski, A., 2022. Tirzepatide once weekly for the treatment of obesity. New England Journal of Medicine, 387(3), pp.205-216.
• Lars Wichmann Madsen, Jeffrey A. Knauf, Carsten Gotfredsen, Andrew Pilling, Ingrid Sjögren, Søren Andersen, Lene Andersen, Anne Sietske de Boer, Katia Manova, Afsar Barlas, Sushil Vundavalli, Niels C. Berg Nyborg, Lotte Bjerre Knudsen, Anne Marie Moelck, James A. Fagin, GLP-1 Receptor Agonists and the Thyroid: C-Cell Effects in Mice Are Mediated via the GLP-1 Receptor and not Associated with RET Activation, Endocrinology, Volume 153, Issue 3, 1 March 2012, Pages 1538–1547
• Mounjaro Prescribing Information. (2021). Mounjaro (tirzepatide) injection. Eli Lilly and Company.
• Rosenstock, J., Wysham, C., Frías, J.P., Kaneko, S., Lee, C.J., Landó, L.F., Mao, H., Cui, X., Karanikas, C.A. and Thieu, V.T., 2021. Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1): a double-blind, randomised, phase 3 trial. The Lancet, 398(10295), pp.143-155.Sinha R, Papamargaritis D, Sargeant JA, Davies MJ. Efficacy and Safety of Tirzepatide in Type 2 Diabetes and Obesity Management. J Obes Metab Syndr. 2023 Mar 30;32(1):25-45.
• Rosol TJ. On-target Effects of GLP-1 Receptor Agonists on Thyroid C-cells in Rats and Mice. Toxicologic Pathology. 2013;41(2):303-309.
• TCTMD. (2024). Tirzepatide bests semaglutide for weight loss in SURMOUNT-5 topline results. Retrieved from https://www.tctmd.com/news/tirzepatide-bests-semaglutide-weight-loss-surmount-5-topline-results
• Unick, J.L., Pellegrini, C.A., Dunsiger, S.I., Demos, K.E., Thomas, J.G., Bond, D.S., Lee, R.H., Webster, J. and Wing, R.R., 2024. An Adaptive Telephone Coaching Intervention for Patients in an Online Weight Loss Program: A Randomized Clinical Trial. JAMA Network Open, 7(6), pp.e2414587-e2414587.