Mounjaro side effects and how long they last

What are the side effects of Mounjaro? Starting any new treatment can be daunting as there are lots of things you need to be aware of, including the potential side effects that come with it and how to handle them.

Just like all medications, Mounjaro can cause side effects, but not everyone will experience them. If you are already beginning to experience side effects, then you will want to know how long Mounjaro side effects last.

We will talk you through the different side effects of Mounjaro and how you can manage them to help make your weight loss journey as smooth as possible.

Common side effects of Mounjaro

When you get Mounjaro for weight loss you might start to experience some side effects. Side effects usually begin within a couple of weeks after starting the treatment. Over time, your body starts to adjust to the medicine.

Gastro-intestinal symptoms

The gastro-intestial symptoms of Mounjaro are the most common symptoms. They are typically mild and are manageable for most people. They include:

How long digestive side effects last

When you start your Mounjaro journey it is common for you to experience digestive side effects. The side effects can differ in each person and your personal or family history can play a role in this, especially if you have a history of gasto-intestinal problems.

Digestive side effects normally last for a few days or weeks. The mild side effects will usually go away on their own; they don’t need any treatment. You will notice that they will subside within a few weeks when your body starts to adapt to Mounjaro. If they last longer, it is important that you speak to your prescriber for advice.

Managing your side effects after dosage increases

When you start to increase your dosage of Mounjaro, you might become aware that your symptoms are more noticeable. You might even notice that they have gotten worse. Again, your body needs to adjust to the higher dose before the symptoms start to ease. Your prescriber will tell you when to increase your Mounjaro dose.

The worst part of nausea, vomiting and diarrhoea occurs when the dose of Mounjaro is increased. After a short while, this will decrease.

For most mild side effects of Mounjaro, such as bloating and stomach issues, you will be able to purchase over the counter (OTC) remedies to help you with these symptoms.

You should also continue to drink plenty of water and eat smaller meals, as this can help with side effects such as nausea. You should also stop eating when you are full, avoid fatty foods and try to eat bland foods like toast, crackers and rice.

You can also take painkillers such as paracetamol to ease stomach discomfort.

However, if you are experiencing severe symptoms that are interrupting your daily life, then you must contact your prescriber so they can advise you on what to do about your side effects.

Serious side effects

Some people will experience serious side effects but this is rare. Serious unwanted effects of Mounjaro include:

  • Severe digestive problems
  • Acute kidney injury
  • Gallbladder problems
  • Pancreatitis
  • Increased risk of thyroid cancer
  • Hypoglycemia (low blood sugar)
  • Changes in vision
  • Severe stomach problems
  • Serious allergic reactions

When to see a doctor

If you are experiencing severe side effects that don’t go away on their own or with management, then you should contact your doctor or prescriber for advice. As soon as you experience any severe unwanted effects then it is important that you speak to a healthcare professional immediately so that you can get medical treatment.

If your side effects become unbearable or you feel like they are very serious or life threatening then you should either call 999 or visit accident and emergency (A&E) straight away.

Allergic reactions

An allergic reaction to Mounjaro can vary from mild to severe. A severe allergic reaction is classed as a medical emergency as it can be life threatening. Mild or serious symptoms of an allergic reaction can include:

  • Skin rash
  • Itching
  • Flushing
  • Swelling under your skin, in your eyelids, lips, hands or feet
  • Swelling of your mouth, tongue or throat, which can make it hard to breathe

If you believe you are experiencing any symptoms of an allergic reaction you should contact a healthcare provider straight away. Your healthcare provider or prescriber will assess the situation and will decide if they are going to discontinue Mounjaro.

If you are experiencing serious symptoms of an allergic reaction then you should call 999 or visit A&E straight away.

Serious hypersensitivity reactions can occur in users of Mounjaro. These include anaphylaxis and angioedema.

Symptoms caused by accidental overdose

It is possible to overdose on Mounjaro, however, as the MHRA have only recently approved it, there is limited information regarding this.[1]

If you have accidentally overdosed on Mounjaro then please contact ourselves or your GP as soon as possible. You might notice that you are experiencing symptoms that you haven’t so far. Your current symptoms might also worsen. You should seek help immediately if you accidentally overdose.

Are there any long term side effects?

Mounjaro has a good safety profile and unwanted long term effects are unlikely, but you should report any unusual symptoms to your prescriber.

Uncommonly you may develop issues with your pancreas, gall bladder or kidneys. If you notice any unusual symptoms in your abdomen, or in the area of your kidneys, you should report this to ourselves or your GP.

If you notice any neck swelling or pain in the throat area you should also mention this to your healthcare professional.

Avoiding low blood sugar levels

When using Mounjaro alone, it shouldn’t cause low blood sugar. However, if you are taking other medications, including other diabetes medications alongside Mounjaro, then you could be at a higher risk of hypoglycemia (low blood sugar). You must tell your prescriber if you are taking any other medications before you start using Mounjaro.

If you are diabetic it is important to let our team know in your consultation notes.

Your blood sugar levels can be monitored with a continuous glucose monitor (CGM)

Symptoms of low blood sugar include:

  • Tremor
  • Sweating
  • Hunger
  • Tiredness
  • Dizziness or weakness

Staying hydrated

If you experience side effects such as vomiting and diarrhoea then this can put you at an increased risk of dehydration.

Make sure that you are keeping on top of your water intake to avoid becoming dehydrated. You should aim to drink 6-8 glasses of water per day. Staying hydrated can also help to protect you from kidney damage.

Ensuring that you are drinking enough water can also help with symptoms such as constipation.

Does your medical or family history make you more likely to experience side effects?

Your medical history can put you at an increased risk of experiencing problems when using treatments like Mounjaro for weight loss.

If you have a diagnosis of gastroparesis, then it would be dangerous to use Mounjaro, as this could worsen this condition.

We cannot recommend Mounjaro if you have a history of an eye condition called Diabetic Retinopathy.

If you have a personal or family history of Medullary Thyroid Carcinoma (MTC) then treatment with Mounjaro is not advised. If you have a history of Multiple Endocrine Neoplasia syndrome type 2 (MEN2) then we would not recommend Mounjaro. Your healthcare provider will talk you through other weight loss options. [2]

Will I have to end my treatment if symptoms are severe?

If you start experiencing severe side effects of Mounjaro then you should speak to your prescriber straight away. They will be able to advise you if you should continue using Mounjaro.

If it is decided that terminating the treatment is the best option for you then other treatments will be discussed so that you can continue your weight loss journey.

The severity of your symptoms will help your prescriber decide whether your treatment should be discontinued. If your symptoms are serious then it is likely you will be advised to end your treatment.

Will I get withdrawal symptoms after treatment?

Mounjaro is not a stimulant, so you should not feel withdrawal symptoms when you stop treatment. However some users may experience side effects when they stop using Mounjaro. These include:

  • Headaches
  • Insomnia 
  • Increased appetite
  • Increased cravings

If you have titrated up to the higher doses of Mounjaro, it may be necessary for you to gradually reduce your dose at the end of your treatment.

Your weight loss journey is individual to yourself. It is important that you keep an eye on your side effects. Not everyone will experience them and if you do experience side effects, in most cases they will go away on their own.

Always remember to speak to your prescriber if you are struggling with the side effects of Mounjaro. They will be able to give you advice on how to manage them.

If you start to experience any severe symptoms then you should always seek immediate medical treatment.

Olivia Malone - Medical Content Writer
James O'Loan - CEO & Superintendent Pharmacist
James O'Loan , CEO & Superintendent Pharmacist on 12 December 2023
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