Mounjaro

Mounjaro, a type 2 diabetes treatment, has recently received attention online because of its weight loss properties. It works by reducing high blood sugar (glucose) levels in patients diagnosed with type 2 diabetes, but it has been shown to cause weight loss. It is an injectable medication that contains the active ingredient tirzepatide.

Mounjaro is not currently licensed for weight loss, but may soon be approved for weight loss, similar to the recent approval of Wegovy. Below we discuss Mounjaro in more detail and whether it is likely to become available in the UK for weight loss.

Weight Loss Treatments

What is Mounjaro?

Mounjaro is an injectable treatment for people with type 2 diabetes who have high blood sugar (blood glucose) levels. It contains the active ingredient tirzepatide. Mounjaro should be taken alongside a diet and exercise plan to reduce blood sugar levels naturally.

Mounjaro is usually prescribed if you cannot take metformin, another type 2 diabetes treatment. It can also be used alongside other treatments if they do not control your blood sugar levels. You can only get Mounjaro on prescription.

Is Mounjaro available for weight loss?

Mounjaro is a new treatment recently approved in the US Food and Drug Administration (FDA) for type 2 diabetes. Mounjaro is not yet available for weight loss and is not currently licensed for use in the UK.

Although Mounjaro is unavailable for weight loss, other injectable medications and weight loss treatments are available in the UK.

How does Mounjaro work?

Mounjaro contains the active ingredient tirzepatide. It is the first medication that imitates 2 different hormones that can reduce blood sugar. These hormones are:

glucagon-like peptide-1 (GLP-1)
glucose-dependent insulinotropic polypeptide (GIP)

Both GIP and GLP-1 increase the production of insulin in your body. Insulin is essential for reducing and maintaining blood sugar levels. When injected, Mounjaro can help people with type 2 diabetes to control and manage high blood sugar levels.

Mounjaro also increases the time it takes to empty your stomach, which means your blood sugar levels are less likely to spike (get too high). As an added benefit, slowing down the emptying of your stomach makes it easier to feel fuller for longer, which can also help with weight loss.

Mounjaro can also improve the way your body breaks down sugars and fats, leading to weight loss in some patients.

How long does it take for Mounjaro to work?

Mounjaro should start working immediately, but it may take several weeks until your blood sugar is at a normal level.

For weight loss, studies have found that in some cases people who used the largest dose of Mounjaro, 15 milligrams, lost as much as 21% of their body weight.

What are the side effects of Mounjaro?

Mounjaro has some side effects, although not everybody will get them.

Very common side effects of Mounjaro include:

diarrhoea
feeling sick (nausea)

These side effects are not usually severe and are most likely to happen when you first start taking Mounjaro. Mounjaro is introduced gradually to reduce these side effects, allowing your body to adjust to the treatment. Very common side effects should improve within a few weeks, but speak to your doctor if they persist.

Mounjaro can also cause low blood sugar when used with other medicines for type 2 diabetes, such as insulin. Tell your doctor if you get symptoms of low blood sugar, which include shaking, sweating, dizziness, hunger, and an increased heart rate.

Common side effects of Mounjaro include:

fast pulse
mild to moderate allergic reaction, such as eczema, itching, or rash
decrease in appetite
pain in the stomach
vomiting (being sick)
constipation
indigestion
bloating
gas and burping
heartburn or reflux
fatigue
an increase in the levels of pancreatic enzymes, which will show up on a blood test
itching, redness, or irritation at the injection site

Uncommon side effects of Mounjaro include:

gallstones
an increase in calcitonin (a hormone that helps to control calcium levels)

How to manage the side effects of Mounjaro

To manage the side effects of Mounjaro, you can:

take your treatment at the same time and day each week
manage nausea symptoms by sipping cold water, avoiding greasy, heavy meals, and eating smaller meals more often
make sure to eat enough fibre (if you get constipation)
stay hydrated if you have diarrhoea or nausea
take anti-diarrhoea tablets
only take the dose prescribed to you and avoid increasing your dose unless your doctor tells you to
let your doctor know if you have any side effects that bother you or aren’t going away on their own
speak to your doctor if you take other medications that may interact with Mounjaro or cause side effects

Are there any long term side effects?

Mounjaro is not known to cause any long term side effects. If you do get any side effects, they will probably go away or get better within a few weeks or will stop when you stop taking the medicine.

Are there any serious side effects of Mounjaro?

Mounjaro, like other medications, can cause a serious allergic reaction. This is known as anaphylaxis and causes breathing difficulties, throat, face and mouth swelling, and fainting.

Mounjaro can also cause an inflamed pancreas, known as acute pancreatitis. This requires urgent medical attention, so speak to your doctor or call 111 or 999 if you have intense and persistent stomach and back pain.

How to take Mounjaro for type 2 diabetes

When taking Mounjaro for type 2 diabetes, it should be injected once weekly, at the same time and day of the week. Your dose is increased slowly, and each pen is pre-filled with the correct dose.

You can use Mounjaro at any time in the day but make sure this is the same time every week.

Who can use Mounjaro?

Mounjaro is suitable for people diagnosed with type 2 diabetes who need help regulating their blood sugar levels.

You should not use Mounjaro if you are allergic to any of the ingredients in the injection, especially tirzepatide. Mounjaro is also unsuitable for anyone under the age of 18. If you are pregnant or breastfeeding, Mounjaro is not recommended.

Speak to your doctor before using Mounjaro if you have:

a severe health condition that affects the emptying of your stomach, such as severe gastroparesis
an eye condition, such as diabetic retinopathy
ever had pancreatitis, which is an inflammation of the pancreas

Interactions with other medications

Mounjaro may interact with other medications, so speak to your doctor if you take any prescription or over-the-counter medications, or herbal remedies. You should also inform your doctor if you use another diabetic medication, especially insulin or sulphonylurea.

Interactions with food/drinks

No food or drink interacts with Mounjaro, but you may want to avoid excessive alcohol consumption. Alcohol can affect your blood sugar levels and make Mounjaro less effective.

Will tirzepatide become available for weight loss in the UK?

Tirzepatide is currently unlikely to become available for weight loss in the UK soon.

When approving a new medication, it must go through clinical trials to ensure it is safe and effective. This can take several years. Tirzepatide may be available in the future for weight loss, but for now, other similar, effective medications are available.

What medication can I take to help me lose weight?

A table comparing various weight loss medications

If you are looking for a weight loss treatment, many options are available in the UK, depending on whether you want an injection or a tablet.

Weight loss injections

The weight loss injections currently available in the UK include:

Saxenda, which contains the active ingredient liraglutide, is taken once daily and is gradually increased to a maximum dose of 3mg a week

Available off label if prescribed for weight loss:

Wegovy, a new weight loss treatment which contains semaglutide, is taken once a week and has a maximum dose of 2.4mg
Victoza, an ‘off label’* medication when used for weight loss, contains the active ingredient liraglutide and is taken once a day
Trulicity, also available ‘off label’ as a once-weekly injection and contains the active ingredient dulaglutide

These injections are all used as type 2 diabetic treatment but can also contribute to weight loss.

*If a medication is prescribed as ‘off label’, a doctor can prescribe it for something other than its primary intended use.

Weight loss tablets

A range of weight loss tablets are also available if you do not want to use an injectable pen. These include:

Xenical, a prescription medication containing orlistat, which causes around a third of the fat eaten at meals to be excreted rather than digested
orlistat, an unbranded version of Xenical, which works in the same way
Alli, an over-the-counter version of orlistat, which comes in a lower dose
Mysimba, a prescription medication that contains bupropion and naltrexone hydrochloride, which work on the areas of your brain controlling energy and hunger levels

Sources

EMC (2022). Mounjaro 10mg solution for injection in pre-filled pen: https://www.medicines.org.uk/emc/product/14203/pil, retrieved 06/06/2023

EMC (2022). Saxenda 6 mg/mL solution for injection in pre-filled pen: https://www.medicines.org.uk/emc/product/2313/smpc, retrieved 12/05/2023

EMC (2022). Wegovy 1 mg, FlexTouch solution for injection in pre-filled pen: https://www.medicines.org.uk/emc/product/13801/smpc, retrieved 12/05/2023

Mounjaro (2022). How to use Mounjaro: https://www.mounjaro.com/how-to-use-mounjaro#how-to-use, retrieved 06/06/2023

The New England Journal of Medicine (2022). Tirzepatide Once Weekly for the Treatment of Obesity: https://www.nejm.org/doi/full/10.1056/NEJMoa2206038, retrieved 06/06/2023

Weight Loss Treatments

Mounjaro

Mounjaro