Tirzepatide (Mounjaro)

Web Resource Last Updated: 18-05-2026

 

Tirzepatide (Mounjaro) is an injectable medication that is not insulin for people with type 2 diabetes. It is similar to the GLP-1 analogues. Tirzepatide and the GLP-1 analogues together are sometimes called “non-insulin injectables” or “incretins”.
 

How does Tirzepatide work?

 
Tirzepatide works in the same way as two hormones that your body produces naturally called GLP-1 and GIP. These hormones help you:
 
  • Produce more insulin, but only when needed
  • Reduce the amount of glucose being produced by the liver when it’s not needed.
  • Slow down the digestion of food
  • Feel full sooner
  • Reduce your appetite
 
These effects mean that, for the majority of people with type 2 diabetes, Tirzepatide:
 
  • Improves blood glucose
    • In the short term, this means fewer symptoms of high blood glucose levels (such as feeling thirsty).
    • In the long term, this means lower risk of developing problems with your eyes, kidneys and feet.
  • Helps with weight management
    • Most people taking Tirzepatide also lose weight, which is beneficial for a lot of people with type 2 diabetes.
There is some evidence that Tirzepatide may also have additional benefits in protecting against heart disease, stroke, kidney disease and a liver problem known as Metabolic Dysfunction Associated Liver Disease (MASLD).

 

How is Tirzepatide taken?

Tirzepatide is taken as an injection just under the skin, which you do yourself, using a device that looks a lot like a pen. You give yourself the injections once a week.

The dose is increased gradually, over a period of weeks or months, based on how well you’re getting on with it and how much benefit you’re noticing.

Tirzepatide with other medications

Tirzepatide slows down how quickly food leaves the stomach. This helps with blood sugar and appetite, but it can also affect how your body absorbs other medications. There are a few medications that you should discuss with your healthcare team before you start Tirzpatide:
  • Warfarin or Levothyroxine
    • you may need more monitoring with blood tests when you start on Tirzepatide or after a change in dose.
  • Contraception
    • If you are taking the oral contraceptive pill you should use a barrier method of contraception (e.g. condoms) in addition to your pill for
      • four weeks after starting the medication AND
      • for four weeks after any increase in dose
    • Alternatively, you may wish to consider another (non-oral) method of contraception whilst using Tirzepatide.
    • Your healthcare team will advise you of any monitoring or changes of medication that you might need.
    • More information on all aspects of contraception for people taking Tirzepatide can be found in this patient leaflet
  • Hormone replacement therapy (HRT)
    • If you take a tablet form of progesterone or you are unsure what sort of tablet HRT you take, you should speak to your healthcare team. They may suggest a change in dose or moving to an alternative form of HRT.
    • If you notice any unusual bleeding, you should inform your healthcare team as soon as possible

 

Who can have Tirzepatide?

 
Your healthcare team will talk to you about whether Tirzepatide might be right for you. It can be used for:
 
  • blood sugar control
  • weight management
  • blood sugar control AND weight management
 
Your healthcare team will talk with you about how you and they feel your diabetes is going, what treatment you use now, any other health problems you have, as well as what is most important to you. They will also only be able to recommend Tirzepatide on the NHS if you fit the national guidelines (see below). The guidelines are put together by the government organisation called NICE (National Institute for Clinical Excellence) and can seem confusing, but your healthcare team will guide you through this. It’s good to remember that Tirzepatide doesn’t work for everyone, and some people might get side effects or feel unwell when taking it.
 

Tirzepatide for blood sugar control

The NICE criteria for blood sugar control were updated in February 2026 and are as follows:

 

As initial / starting treatment:
 
  • People diagnosed with type 2 diabetes under the age of 40 – NICE advise “considering” a GLP-1 analogue or Tirzepatide (Mounjaro) in combination with other medications*
*If you are being started on a combination of medicines, your healthcare team will start them one by one. This is to make sure each medicine suits you before moving on to the next.
 
After starting initial treatment:
 
  • People living with obesity (Body Mass Index [BMI] of 30kg/m2* or above) – NICE advises “considering” a GLP-1 analogue Tirzepatide (Mounjaro) if
    • On initial treatment for at least 3 months AND
    • Additional medicines needed to reach a person’s individualised blood glucose control targets
*27.5kg/m2 for people with South Asian, Chinese, other Asian, Middle Eastern, Black African or African–Caribbean background
 
  •  People diagnosed with type 2 diabetes under the age of 40 and were not taking a Tirzepatide before – NICE advise “considering” a GLP-1 analogue or Tirzepatide (Mounjaro)
There is a lot of research being done on Tirzepatide and it is likely that the guidelines will change. This means that your healthcare team may wish to discuss your treatment with you between your routine appointments.

 

Tirzepatide for weight management alone 

 
NICE have produced advice and guidelines on who can have Tirzepatide and when the treatment will be available under the NHS. This is because, for the first few years, not everyone will be able to have Tirzepatide.
 
Tirzepatide is an option for adults living with overweight or obesity who:
 
  • are following a reduced-calorie diet AND
  • are increasing their physical activity AND
  • have an initial body mass index (BMI) of at least 35 kg/m2* AND
  • have at least 1 medical problem associated with overweight or obesity**
*27.5kg/m2 for people with South Asian, Chinese, other Asian, Middle Eastern, Black African or African–Caribbean background
 
**Medical problem associated with overweight or obesity
 
  • type 2 diabetes
  • high blood pressure
  • abnormal blood fats
  • obstructive sleep apnoea
  • cardiovascular disease (for example, heart attack or stroke)
The first group of people who will qualify are those with:
 
  • 4 or more of the listed weight-related health conditions AND
  • a BMI of 40 kg/m2 or more.
The full timeline for who can have Tirzpatide on the NHS can be found here

 

What are the side effects of taking Tirzepatides?

Not everybody will experience side effects from taking this type of medication, however, the most common ones include:

  • Diarrhoea
  • Nausea
  • Vomiting
  • Headaches
  • Dizziness
  • Increased sweating
  • Indigestion
  • Constipation
  • Loss of appetite

Most of the side effects usually go away over time. Sometimes reducing the dose or changing your diet can help.

However, there are two very rare but more serious side effects that you should report immediately to your healthcare team:

Severe stomach pain

If you have severe and persistent stomach pain, which may go through to your back, with or without vomiting, you must stop taking the Tirzapetide and contact your doctor immediately. This may be a sign of pancreatitis (inflammation of the pancreas).

Sudden changes in vision

If your eyesight suddenly worsens or you experience sudden blindness while taking a GLP-1 agonist, stop the medication and go straight to the eye casualty department (if available in your area) or A&E.


There are also some much less common side effects to look out for:

Low blood sugar (hypoglycaemia)

On it’s own, Tirzepatide will not cause your blood glucose level to go too low (hypoglycaemia = blood glucose level less than 4 mmol/L), but it may increase the risk of this happening if you also take insulin or drugs called sulphonylureas (e.g. gliclazide).

High blood sugar (hyperglycaemia)

If you take insulin as well as Tirzepatide and the insulin is reduced very quickly, then blood sugars can rise (known as hyperglycaemia). Very rarely, the blood sugars rise very high and cause diabetic ketoacidosis (“DKA”).

If you experience any side effects, please discuss them with the doctor or nurse caring for you.

Problems with anaesthetics

Tirzepatide can slow down how quickly your stomach empties. If you take Tirzepatide and need an operation with a general anaesthetic (being fully asleep) or deep sedation, there is a risk that food or drink may still be in your stomach. This can sometimes travel into the lungs during surgery, which can be dangerous.

If you are taking Tirzepatide, tell your healthcare team, especially the anaesthetist, well before your procedure. They can adjust your preparation and anaesthetic plan to keep you safe.

 

Getting the most from your medication

Tirzepatide will help you achieve your weight and blood sugar goals best if taken regularly and combined with healthy lifestyle changes. There are specific dietary modifications that can also reduce the risk of side effects, for example eating small, regular, healthy meals and drinking plenty of water.

Making sure your medication is working

It is important that you attend your regular clinic appointments. After you’ve been taking the medication for a while, your healthcare team will invite you back to check how you’re feeling and whether the treatment is helping. This is a chance to talk about what’s going well and anything that’s been difficult. Depending on how things are going, they might suggest adjusting the dose or stopping it and trying a different medicine. These decisions will be based on the reasons the Tirzepatide was started and the goals you agreed together.

Frequently asked questions


Tirzepatide and Driving

Tirzepatide should not affect your ability to drive, cycle or use machinery or tools as long as your blood glucose levels are stable. You should never drive with a low blood sugar level. On it’s own, Tirzepatide will not cause your blood glucose level to go too low (i.e. cause hypoglycaemia, which is classed as a blood glucose level less than 4 mmol/L), but it may increase the risk of this happening if you also take insulin or drugs called sulphonylureas (e.g. gliclazide).

Check with your diabetes care team if you would like further guidance, or have a look at the national guidelines for driving when you have diabetes.

What if I forget to take my medication?

If you forget to take a dose, then take it as soon as you remember unless it’s more than 4 days late. If it is more than 4 days late, skip the missed dose and just take your next one at the normal time. In either case, you can then resume your regular once weekly dosing.

Do not take a double dose to make up for a missed one.

Can I buy Tirzepatide over the counter?

If you do not fit the guidelines from NICE, it is possible to buy Tirzepatide privately but you will still need a prescription. You must have a consultation with a healthcare professional before the prescription can be issued, so that the prescriber can carry out proper checks and make sure you are aware of the benefits and risks of taking the medicine.

Buying Tirzepatide without a prescription can put your health at serious risk and the seller is breaking the law. You can find more advice about buying Tirzepatide privately online at the Gov.uk and Greater Manchester Integrated Care Partnership websites, including information on how to tell if a pharmacy is legitimate.

If you do buy Tirzepatide privately, make sure to tell your healthcare team so they can make sure your treatment is safe.

What do I do if I am trying for a baby?

We do not know if taking a Tirzepatide is safe when trying for pregnancy, during pregnancy or when people are breastfeeding. Therefore, if you are planning to start a family, you should speak to your healthcare team about when you should stop your Tirzepatide and when you can re-start it.

When will my healthcare team stop Tirzepatide / GLP-1?

Your healthcare team will talk to you about stopping Tirzepatide if

  • You become underweight (BMI <18.5 kg/m2).
  • The medication is not helping reach your blood sugar targets and is not being used to also reduce your risk of heart attacks and strokes.

NOTE: If a Tirzepatide has been prescribed within the NHS but outside of national guidelines, your clinical team will need to review your treatment and may stop your prescription.

Can people with type 1 diabetes use Tirzepatide?

At present Tirzepatide is only licensed for people with type 2 diabetes

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