Mounjaro Side Effects & How to Manage Them Effectively

Introduction to Mounjaro (Tirzepatide)

Mounjaro is an injectable medication used for weight management alongside an improved diet and exercise regime. Mounjaro was launched in the UK in November 2023.

The active ingredient tirzepatide is a GIP and GLP-1 receptor agonist. Tirzepatide selectively binds and activates both of these receptors, mimicking these natural hormones in the body.

Research into tirzepatide therapy in diabetes found it led to greater improvements in blood glucose and weight management when compared to other diabetes type 2 medications.

The tirzepatide injection has shown significant effects in both diabetes and weight reduction due to the way it works:

• Reducing fasting and postprandial (during or after eating) glucose concentrations.

• Enhancing insulin secretion.

• Improving insulin sensitivity.

• Decreasing food intake.

As with all medication, Mounjaro can cause side effects. These can include gastrointestinal issues such as nausea and vomiting. There is also an increased risk of rare but severe symptoms such as pancreatitis and certain thyroid cancers.

Common Side Effects of Mounjaro

Gastrointestinal Disturbances

Mounjaro delays stomach emptying which can lead to gastrointestinal disturbances. The most common adverse reactions include:

• Nausea

• Vomiting

• Abdominal pain

• Decreased appetite

• Constipation

• Indigestion

• Diarrhoea

These side effects are more common/a-z-departments/rheumatology/injection-site-reactions.aspx) when starting Mounjaro and when increasing the dose and generally decrease with continual use.

Injection Site Reactions

Injection site reactions/a-z-departments/rheumatology/injection-site-reactions.aspx) can be common with any injectable medicine. It is important to rotate the site you inject to prevent scar tissue from forming. Common reactions include:

• Redness

• Itching

• Swelling

• Pain

These reactions usually occur 1-2 days after injecting, are mild and go away within 3-5 days. If you experience any of the following reactions, seek medical attention immediately:

• Fever - 38C or higher.

• Severe pain or blistering at the injection site.

• Muscle aches.

• Nausea, vomiting, headache or dizziness.

• Skin rash, hives, or severe itching.

Hypoglycemia (Low Blood Sugar)

Low blood sugar (hypoglycemia) is not a registered side effect but can occur if you are taking other medications that also lower blood sugar alongside Mounjaro. These include insulin and sulfonylureas. It is important to keep an eye out for symptoms of low blood sugar which include:

• Dizziness/light-headedness/confusion

• Sweating

• Drowsiness

• Headache

• Blurred vision

• Slurred speech

• Fast heartbeat

• Anxiety

• Irritability

• Hunger

• Weakness

• Shaking

Other Notable Side Effects

Other notable side effects of Mounjaro include:

• Pancreatitis - Inflammation of the pancreas. Symptoms include severe abdominal pain which spreads to the back or chest and is accompanied by fever or nausea/vomiting. You must stop using Mounjaro if these occur and seek immediate medical help.

• Allergic reactions - Symptoms include: swelling of the lips, tongue, throat or face, difficulty swallowing, problems breathing, severe rash or itching, a rapid heartbeat, fainting or dizziness.

• Kidney issues (kidney failure) - If you have any kidney issues, experiencing the common side effects such as diarrhoea, nausea and vomiting, can lead to a loss of fluids, ultimately leading to dehydration. This is why it is important to maintain an adequate fluid intake.

• Gallbladder problems - This includes cholecystitis and gallstones. If you experience any upper abdominal pain, clay-coloured stools and/or yellowing of the eyes and skin, stop using Mounjaro and seek medical help from a healthcare professional. Gallbladder issues have been reported in those using Mounjaro.

• Vision changes - Please contact your healthcare professional if you experience any vision changes.

• Stomach problems - If you have stomach pain that won't go away, contact a healthcare professional.

If you experience any of the above side effects, you must stop using Mounjaro and seek immediate medical help.

Serious Side Effects and Their Indicators

Thyroid C Cell Tumors and Cancer Risks

A personal or family history of thyroid cancer or if you have multiple endocrine neoplasia type 2 (MEN2) usually means Mounjaro is not suitable for you. This is due to an increased risk of thyroid tumors and thyroid cancers.

When undergoing clinical studies, tirzepatide caused dose-dependent and treatment-duration-dependent thyroid C cell tumors in male and female rats. It is unknown whether Mounjaro causes thyroid c cell tumors and medullary thyroid carcinoma (MTC) in humans.

Symptoms of thyroid tumors include:

• Difficulty swallowing

• Difficulty breathing

• Persistent hoarseness

• A lump that can be felt in the throat - this will feel hard, slowly gets larger and is not painful

• Pain in the neck or throat

• A sore throat

Other symptoms may include:

• Unintentional weight loss

• A cough

• Softer poos or diarrhoea

• A red face (flushing) - this may be more difficult to see on darker skin.

If you notice any of these symptoms, stop using Mounjaro and seek immediate medical attention.

Acute Gallbladder Disease

Acute gallbladder disease occurs when a gallstone blocks the cystic duct, which is the main opening of the gallbladder. This condition is also known as acute cholecystitis.

Acute gallbladder disease is a side effect of Mounjaro that has occurred in clinical trials. In a group of 718 participants, 0.6% of patients treated with Mounjaro reported acute gallbladder disease, compared to 0% taking a placebo.

The main symptom is a sharp, sudden pain in the upper, right of the abdomen which can spread to the right shoulder. The pain will be persistent and will not go away. Other symptoms include:

• A high temperature

• Nausea/vomiting

• Sweating

• Loss of appetite

• Yellowing of the skin and eyes

If you experience these symptoms, stop using Mounjaro as this is a medical emergency and seek medical help immediately.

Acute Kidney Injury

Mounjaro side effects include nausea, vomiting and diarrhoea. These can all lead to dehydration which, if severe, can lead to acute kidney injury.

In some patients treated with GLP-1 receptor agonists, post-marketing reports have highlighted acute kidney injury and worsening of chronic renal failure. Some of these events were reported in patients who had no known underlying renal disease.

It is extremely important to stay hydrated whilst taking Mounjaro as dehydration can negatively affect kidney function, regardless of previous kidney issues.

Early signs of kidney problems include:

• Tiredness, low energy and trouble concentrating

• Difficulty sleeping

• Dry/itchy skin

• Urinating more often

• Blood in urine

• Foamy urine

• Puffy eyes

• Swollen ankles and feet

• Poor appetite

• Muscle cramping

Diabetic Retinopathy

Mounjaro can used to treat high blood sugar in patients with or without type-2 diabetes. When there is a rapid reduction of blood glucose, this can lead to a temporary worsening of diabetic retinopathy in patients.

Patients with a history of this should be monitored for progression of diabetic retinopathy.

Reducing and Managing Side Effects

Lifestyle Modifications

It is important to make the necessary changes to your lifestyle when using Mounjaro including changes to your diet and exercise routines. This can also contribute towards minimising side effects.

Stay hydrated - Symptoms such as nausea, vomiting and diarrhoea can cause dehydration which may lead to kidney injury. Staying hydrated can help prevent this.

Avoid overeating - It is important to stop eating as soon as you feel full, even if this is early on in a meal. Nausea and vomiting are common in patients who overeat beyond the fullness point.

Injection site reactions - Ensure you are rotating the site you inject to prevent a build-up of scar tissue/swelling.

Exercise - This can of course help along your weight loss journey but can also aid digestion and relieve constipation. It can also help to combat weakness and fatigue.

Eat well - Limit spicy, acidic foods which can irritate your stomach and opt for more gentle foods such as oats, bananas, toast and potatoes.

Medication and Dose Adjustments

It is important to inform your healthcare provider of any existing medication you are currently taking if you are considering Mounjaro treatment. As Mounjaro alters gut transition, the contents of the gut, including oral medication, may exhibit an altered absorption. A result of this may be that previously controlled conditions have a temporary flare-up.

Your clinician is optimally placed to provide specific advice based on any other medications you may be taking and whether these are safe alongside Mounjaro. If a dose adjustment is required, this will be made by your GP.

If you are taking the hormonal contraceptive pill whilst using Mounjaro, you will need to use an additional barrier method during the first 4 weeks after initiating treatment and for the first 4 weeks after each dose increase. You could also switch to another method of contraception such as the coil. Birth control is imperative with Mounjaro.

Monitoring and Early Detection

Here at Quick Meds, we require our patients to complete a monthly health questionnaire before ordering. This allows us to monitor for adverse events related to Mounjaro and assess weight loss progression. It also accounts for any changes in your medical history to be taken into account to ensure continuous safe prescribing.

This ordering process allows our clinicians to identify potential issues and track your progress. This directly informs the prescribing process where dose adjustments can be made if necessary and opportunistic advice provided to ensure safe and effective treatment.

At Quick Meds, if you are requesting Mounjaro for the first time, a clinician will follow up with a phone call to provide all the information required for a safe treatment journey from the onset. This is your opportunity to ask any questions you may have or to address any concerns. Knowing how to recognise symptoms can aid early detection of potential side effects, and mitigating against them.

Precautions Before Starting Mounjaro

A consultation with a clinician is required for all patients new to Mounjaro. This helps determine eligibility and safety.

A personal or family history of thyroid cancer can put you at an increased risk if using Mounjaro. Similarly, a previous history of pancreatitis may mean the treatment is not safe for you.

It is important you provide all information pertaining to your health no matter how inconsequential this may seem. This includes any over-the-counter medications or any vitamins you may be taking. This information informs the prescribing decision and helps our clinicians prescribe safely.

When to Seek Immediate Medical Attention

Warning signs to look out for when using Mounjaro include:

Allergic reactions - these can be mild but also quite severe. Symptoms such as swelling of the lips, tongue, face or eyes necessitate immediate medical attention. Other symptoms include difficulty breathing, feel dizzy and pale blue/grey skin.

Acute pancreatitis - severe abdominal pain that may spread to the back or chest, associated with fever or nausea.

Gallstones - severe stomach pain with yellowing of the eyes or skin.

Thyroid cancer - characterised by persistent hoarseness, difficulty swallowing, a lump in the throat, pain in the neck or throat and swollen lymph nodes in the neck.

Hypoglycaemia - or very lower blood sugar levels. This is unlikely unless you are taking diabetic medication or insulin. Symptoms include: feeling hungry, trembling or shaking, sweating, confusion, difficulty concentrating and slurred speech.

If you experience any of the above symptoms, this is a medical emergency and you should contact your doctor immediately.

Comparison with Other Diabetes Medications

Mounjaro - A very effective weight loss medication which works by enhancing insulin secretion, increasing insulin sensitivity and reducing food intake. The most common side effects include nausea, vomiting, constipation and diarrhoea.

The mean reduction in HbA1c levels over 40 weeks using Mounjaro 15mg has been 1.7-2.4% compared to 0.9% with placebo, 1.3% with Tresiba and 1.4% with insulin glargine.

Over a 40-week study, patients using Mounjaro 15mg displayed a mean reduction in body weight of 17-25lbs compared to only 4lbs with either Tresiba or insulin glargine. Patients taking placebo exhibited a mean reduction between -2 and 4lbs.

Wegovy - Containing the active ingredient semaglutide is a GLP-1 agonist only and works by also reducing food intake. Although effective, studies have concluded that Mounjaro may produce greater weight loss.

Clinical trials have determined that 96% of participants using Mounjaro have lost 5% of their body weight in comparison to 84% using Wegovy. Both Wegovy and Mounjaro exhibit a similar side effect profile with gastrointestinal side effects remaining the most common, though these do wear off as the body adjusts to either medication.

The Role of Healthcare Professionals in Mounjaro Treatment

Before treatment with Mounjaro, you must have a consultation with a registered prescriber. Your prescriber can assess your medical history and provide you with all the necessary information required to start your weight loss journey safely and healthily.

Ongoing and open communication with your healthcare provider can make the difference in succeeding in treatment. They are optimally placed to provide opportunistic advice in the case of side effects or advice on how to increase the benefits from the treatment if your results have stalled.

Summary & Key Takeaways

Mounjaro is a proven effective medication used for the treatment of obesity alongside lifestyle modifications.

As with all medication, Mounjaro can cause side effects. In most cases, these side effects are mild in nature and can be mitigated against, through lifestyle modifications.

Keeping in contact with your healthcare provider is important to raise any concerns you have and to help manage expectations and results.

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