Mounjaro is a medication for adults with type 2 diabetes with uncontrolled high levels of blood sugar which has recently been approved for weight loss on private prescription. It is used alongside diet and exercise and in doing so, can help manage your blood sugar levels and can cause weight loss. Mounjaro uses an active substance called tirzepatide and is delivered via subcutaneous injection.

What is Mounjaro Used For?

Mounjaro is a type of diabetic medication. It can either be taken with other diabetic medications when your blood sugar is not well controlled, or it can be used on its own, particularly if you cannot have metformin.

Mounjaro, alongside exercise and a balanced diet, reduces your average blood sugar levels. It is used by people with type 2 diabetes that is not well controlled. As it helps to slow digestion and limits your appetite, and is recommended to be used alongside increased exercise and a controlled diet, some patients have reported losing weight while using Mounjaro. In clinical trials, Mounjaro has been found to help patients lose 15-20% of their body weight in 72 weeks.

How Does Mounjaro Work?

Mounjaro works by enhancing insulin secretion from the pancreas as a result of food. It does this by the attachment of Tirzepatide, the active substance in Mounjaro, to the GIP and GLP-1 receptors of hormones that are produced in the gut. These receptors are normally triggered when you eat; this fills the same role as your body’s hormones, but does so more effectively.

By triggering these receptors, Mounjaro improves insulin sensitivity and decreases your appetite. Mounjaro can cause you to feel more full even when you eat less food, which should decrease calories eaten and can lead to weight loss. This results in an overall reduced amount of sugar in the blood.

Is Mounjaro Approved for Weight Loss?

As of February 2024, Mounjaro has been approved for weight loss on private prescription in the UK through private doctors and online pharmacies such as Simple Online Pharmacy. At the time of writing this however, Mounjaro is only approved for type 2 diabetes through the NHS.

This is because the MHRA (Medication and Healthcare Products Regulatory Agency) has approved the medication for weight loss, allowing it to be prescribed privately, but the NICE (National Institute for Health and Care Excellence) has only approved Mounjaro for type 2 diabetes control. Along with the scarcity and expense of the medication, this results in the NHS being unable to prescribe Mounjaro for weight loss.

What are the Doses for Mounjaro?

Mounjaro can be injected either under the skin of the abdomen, upper arm or thigh. The beginning dose is 2.5 mg once a week for 4 weeks. This should be increased by your doctor to 5 mg after 4 weeks. The dose of Mounjaro can then, if necessary, be increased in 2.5 mg increments to a maximum of 15 mg per week depending on how well your blood sugar is being controlled.

Mounjaro Dosage

This dosing schedule is designed to keep side effects to a minimum, although you may experience them when you increase your dose.

Further information on using Mounjaro can be found in our article on Mounjaro Dosage, or you can contact your pharmacist or doctor.

What are the Side Effects of Mounjaro?

As with any medication, Mounjaro may cause some side effects. These side effects can vary depending on the individual taking Mounjaro. Many of these side effects cause some form of stomach problems. The most common side effects of Mounjaro include:

  • Nausea
  • Diarrhoea
  • Decreased appetite
  • Vomiting
  • Constipation
  • Indigestion
  • Stomach pain


The dosing schedule is designed to reduce these side effects; by building up from a smaller dose, your body has time to adjust to the medication. Ideally, these side effects will pass quickly, and once you reach the “maintenance” dose, they shouldn’t be as much of a concern. You may notice your side effects become worse when you change from one dose to the next.

If your side effects are severe, or you see any signs or symptoms of an allergic reaction (either at the injection site or elsewhere) speak to your doctor or pharmacist. They may recommend you to stay at a lower dose, rather than to increase towards the maintenance dose.

You can find more detailed information on Mounjaro side effects in the Patient Information Leaflet.

Who Can’t Use Mounjaro?

While Mounjaro is safe for most people to use, it does have some contraindications. People with a family history of medullary thyroid carcinoma should not use this medication. Anyone with any of the following medical conditions should talk to their doctor before using Mounjaro;

  • diabetic retinopathy, a type of damage to the eye from diabetes
  • dehydration
  • stomach muscle paralysis and decreased function
  • disease of the gallbladder
  • kidney problems
  • pancreatitis
  • medullary thyroid cancer
  • multiple endocrine neoplasia type 2


Your doctor will advise you on the use of Mounjaro if you may have any of these conditions.


  • Mounjaro is a drug used to control blood sugar levels in adults with type 2 diabetes
  • Mounjaro has been approved for weight loss through private prescription in the UK
  • Side effects can vary but most commonly affect the digestive system


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