Mounjaro prescription service

To understand your target weight, it’s useful to start by calculating your BMI (Body Mass Index).

BMI is a simple measure that uses your height and weight to help determine whether you are within a healthy weight range. For adults, the categories are:

• Under 18.5: Underweight
• 18.5 to 24.9: Healthy weight
• 25 to 29.9: Overweight
• 30 and above: Obese

Calculate your BMI using the NHS tool

If your BMI is 30 or above, or 27 or above with another health condition (such as high blood pressure, high cholesterol, pre-diabetes or heart problems.), you may be eligible for Mounjaro.

It’s important to work towards a healthy BMI through a combination of approaches. Medication alone isn’t an effective long-term solution - weight-loss injections should always be used alongside a balanced diet and an active lifestyle. Not doing so results in dietary deficiencies, reduced bone density and loss of muscle mass, not just body fat.

Before considering Mounjaro, please explore the many structured weight-management programmes available, such as NHS Better Health, Slimming World, or Weight Watchers

Learn more about weight loss services

If you have already tried options like these without success, Mounjaro may be an additional tool to support your progress. However, maintaining healthy habits remains essential both during treatment and after stopping the medication.

There are also many Apps available to assist with lifestyle medicine such as Noom and My Fitness Pal.

Protein – Prioritise protein intake. Protein is essential for muscle growth and repair. A high protein diet can include lean meats, fish, eggs, legumes (beans). Also nuts and seeds which also provide vital micronutrients (trace elements and vitamins) as well as fibre.

Balanced Nutrition – This includes plants, whole foods and healthy fats. This will supply essential nutrients and also fibre. Learn more about eating well

Strength training – To maintain and build muscle, resistance training exercises 2 to 3 times a week as well as physical activity of at least 30 minutes per day. Resistance training can include weightlifting, body weight exercises, or the use of resistance bands. Start slowly and gradually build up. Learn more about how to improve your strength and flexibility

Hydration – Adequate hydration will optimise your physical and mental performance. It will also guard against the common weight loss injection side effects of constipation and other gut symptoms. Aim for at least 6-8 cups/glasses of water each day. Try to cut out drinks with added sugar or sugar substitutes. Limit fizzy drinks and alcohol. Also consider stopping caffeinated coffee and tea from early afternoon onwards. This will help with your sleep pattern.

Supplements – Here the evidence is not so clear cut or consistent. Supplements recommended include Vitamin D and B12, calcium, omega 3 (fish oil) capsules and multivitamins.

Monitor your progress - Track your weight loss, but also consider monitoring your body composition and strength. Be honest with yourself, particularly about lifestyle changes. Remember that it is these that will sustain your weight loss when you stop injections.

Rest – Allow your body adequate time to recover after strength training and physical activity. Muscles grow and repair when you are at rest, not whilst you are working them.

Mounjaro contains the active ingredient tirzepatide, which works by mimicking two natural hormones in your body: GLP-1 and GIP. Together, these dual effects make tirzepatide an effective medication for reducing your appetite and regulating your blood sugars, which can support weight loss when used alongside healthy lifestyle changes. It can help you lose up to 22.5% of your body weight over 72 weeks

Mounjaro comes in a monthly pen which contains enough medication for 4 weekly doses which are injected into an area of fatty tissue.

You can inject into your belly (at least 5cm away from your belly button) or thigh. You can also inject into the back of your upper arm, but would likely need someone else to do this for you.

You should also change the injection site each week.

The initial starting dose is 2.5mg, which can be increased at 2.5mg increments up to a maximum dose of 15mg. The dose you chose to increase to should be based upon the rate of weight loss and how well any side effects are tolerated. You should aim for the lowest dose of medication that achieves a desirable outcome.

A healthy rate of weight loss is considered to be between 0.5kg to 1kg per week.

Mounjaro can be continued indefinitely, however with healthy lifestyle (diet and exercise) adjustments, you may be able to stop Mounjaro once you reach your target weight.

Mounjaro can also be continued to help maintain your weight loss.

Stopping Mounjaro without lifestyle changes will likely result in you regaining your lost weight.

Female patients using oral contraceptives should consider also using a barrier method of contraception (e.g., a condom) or switching to a non-oral contraceptive method for 4 weeks after starting Mounjaro and for 4 weeks after each increase in dose as Mounjaro may affect how well the contraceptive pill works in these patients.

Like all medicines, Mounjaro can cause side effects, although not everyone will experience them. Side effects vary from person to person and often improve as your body adjusts to the medication.

Common Side Effects of Mounjaro

Very Common (may affect more than 1 in 10 people) 

• Nausea (feeling sick) 
• Vomiting 
• Constipation 
• Diarrhoea 
• Stomach pain 
• Low blood sugar* (when used for type 2 diabetes with insulin or sulphonylureas) 

Common (may affect up to 1 in 10 people) 

• Allergic reactions (itching, rash, eczema) 
• Dizziness 
• Heartburn or acid reflux 
• Indigestion 
• Bloating, burping, or excess wind 
• Injection site reactions (redness, itching, bruising, swelling, pain) 
• Low blood pressure 
• Hair loss 
• Feeling tired 
• Gallstones 
• Raised pancreatic enzymes (lipase or amylase) 
• Raised calcitonin levels 
• Low blood sugar (when used with metformin and an SGLT2 inhibitor) 

Most common side effects are mild and usually improve over time. If symptoms persist or become difficult to manage, speak to your doctor. 

Side Effects in People With Type 2 Diabetes 

Some side effects are more common when Mounjaro is used to manage blood sugar levels, including: 

• Reduced appetite 
• Low blood sugar, especially when taken with other diabetes medications 

Symptoms of Low Blood Sugar 

• Dizziness 
• Tiredness 
• Hunger 
• Weakness 
• Confusion 
• Irritability or anxiety 
• Fast heartbeat 
• Sweating 

If symptoms occur, consume a sugary drink or snack (such as fruit juice, glucose tablets, or sweets), followed by a longer-acting carbohydrate like bread or biscuits. Seek medical advice if episodes happen frequently. 

How Long Do Side Effects Last? 

Side effects are most likely when starting Mounjaro or increasing the dose. 

• Mild side effects often improve within a few days to a couple of weeks 
• More severe side effects may take longer and should be discussed with a doctor 

It takes around 25 days for Mounjaro to fully leave your system after stopping treatment. 

Will Side Effects Worsen With a Higher Dose? 

Side effects may return or temporarily worsen when your dose is increased. This usually settles as your body adjusts to the new dose. 

Managing Common Side Effects 

Nausea 

• Eat smaller, more frequent meals 
• Stop eating when you feel full 
• Avoid fatty or spicy foods 
• Choose bland foods (toast, rice, crackers) 
• Take small sips of cold drinks 
• Try ginger or peppermint tea 

Constipation 

• Eat a balanced diet and gradually increase fibre 
• Include fruits such as apples, berries, grapes, and apricots 
• Drink plenty of fluids 
• Increase physical activity 
• Establish a regular toilet routine 

If constipation continues, a pharmacist may recommend a laxative. See your GP if symptoms persist or worsen. 

Diarrhoea 

• Stay hydrated with water or diluted squash 
• Avoid spicy or fatty foods 

Seek medical advice if diarrhoea lasts more than 7 days or if there is blood in your stools. 

Injection Site Reactions 

• Rotate injection sites 
• Clean the skin before injecting 
• Use an ice pack before injection 
• Consider antihistamine tablets or cream 

Less Common and Serious Side Effects 

Uncommon (affect fewer than 1 in 100 people) 

• Fast heartbeat 
• Pancreatitis (inflammation of the pancreas) 
• Gallbladder inflammation (cholecystitis) 
• Changes in taste or skin sensation 
• Delayed stomach emptying 

Very Rare but Serious 

• Severe allergic reactions (anaphylaxis) 
• Angioedema (swelling of the face, lips, tongue, or throat) 

Seek emergency medical help immediately if you experience breathing difficulties, facial swelling, or collapse. 

Pancreatitis 

Stop taking Mounjaro and seek urgent medical care if you experience: 

• Severe, persistent stomach or back pain 
• Fever 
• Ongoing vomiting 

Gallbladder Problems 

Rarely, Mounjaro may cause gallstones or gallbladder inflammation. Symptoms include: 

• Severe upper abdominal pain 
• Fever 
• Yellowing of the skin or eyes (jaundice) 
• Pale stools 

Seek medical advice immediately if these occur. 

When Should I Speak to a Doctor? 

Contact your doctor if side effects: 

• Affect your daily life 
• Do not improve over time 
• Last several weeks 
• Are severe or concerning 

Stopping Mounjaro 

Mounjaro is not known to cause withdrawal symptoms. After stopping treatment: 

• Blood sugar levels may return to previous levels 
• Some people may regain part of the weight lost 

Mounjaro Side Effects FAQs 

Is Mounjaro safe? 
Mounjaro is approved for use in the UK by the MHRA when prescribed by a qualified healthcare professional. 

Does alcohol worsen side effects? 
Alcohol can increase the risk of side effects, including low blood sugar, especially in people with type 2 diabetes. 

Can Mounjaro cause long-term side effects? 
Rarely, ongoing digestive problems, persistent vomiting, or pancreatitis may occur and may require stopping treatment. 

Demonstration Video provided by Lilly on how to use Mounjaro® KwikPen®

You will need the following to inject:

• Mounjaro KwikPen
• 1 Pen Needle (4 x needles provided with each Mounjaro KwikPen)
• 1 alcohol swab (not provided)
• Cotton ball (not provided)
• Sharps container (available to purchase separately)

Step 1

• Wash your hands with soap and water.

Step 2

• Pull the KwikPen cap straight off.
• Inspect the Kwik Pen and label.
  • Do not use if:
    • the medication name or dose strength does not match your prescription.
    • the KwikPen is expired (EXP) or looks damaged.
    • the medication has been frozen, has particles, is cloudy, or is discolored.
  • Make sure the medicine in the KwikPen is colourless to slightly yellow.

Step 3

• Wipe the red inner seal with an alcohol swab.

Step 4

• Select a new pen needle.
• Always use a new pen needle for each injection to help prevent infections and blocked needles.
• Pull off the paper tab from the outer needle shield.

Step 5

• Push the capped pen needle straight onto the KwikPen and twist the pen needle on until it is tight.

Step 6

1. Pull off the outer needle shield and keep it. This will be reused.
2. Pull off the inner needle shield. Put it in your household trash.

Step 7

• Slowly turn the dose knob until you hear 2 clicks and the extended line shown in the dose window aligns with the dose indicator. This is the prime position.
• It can be corrected by turning the dose knob in either direction until the prime position is achieved.

Step 8

• Hold your KwikPen with the needle pointing up.
• Tap the cartridge holder gently to collect air bubbles at the top.

Step 9

• Release some medicine into the air by pushing the dose knob in until it stops, then slowly count to 5 while holding the dose knob. The icon must be shown in the dose window.
• Do not inject into your body.
• Priming removes air from the cartridge and makes sure that your KwikPen is working correctly.
• Your KwikPen has been primed if a small amount of medicine comes out of the tip of the pen needle.
  • If you do not see medicine at the tip of the needle, repeat steps 7-9, no more than 2 additional times.
  • If you still do not see medicine, then change the pen needle and repeat steps 7-9, no more than 1 additional time.
  • If you still do not see medicine, contact us

Step 10

• Choose an injection site.
  • You or another person can inject the medicine in your thigh or stomach (abdomen) at least 5 centimeters from the belly button.
  • Another person should give you the injection in the back of your upper arm.
• Change (rotate) your injection site each week.
• You may use the same area of your body but be sure to choose a different injection site in that area.
• Do not inject:
  • where the skin has pits, is thickened or has lumps
  • where the skin is tender, bruised, scaly or hard
  • into scars or damaged skin
  • into the same injection site used for other medicines.

Step 11

• Turn the dose knob until it stops and the icon is shown in the dose window.
• The icon is equal to a full dose (0.6 mL). 

Step 12

• Insert the needle into your skin.
• Inject the medicine by pushing the dose knob in until it stops.
• Hold the dose knob in and slowly count to 5.
• The icon must be shown in the dose window before removing the needle.

Step 13

• Pull the needle out of your skin.
• A drop of medicine on the needle tip is normal. It will not affect your dose.
• Confirm the icon is in the dose window.
  • If you see the icon in the dose window, you have received the full dose.
  • If you do not see the icon in the dose window, insert the needle back into your skin and finish your injection.
  • Do not redial the dose. If you still do not think you received the full dose, do not start over or repeat the injection. 

Step 14

• If you see blood after you pull the needle out of your skin, lightly press the injection site with gauze or a cotton ball.
• Do not rub the injection site.

Step 15

• Carefully replace the outer needle shield.

Step 16

• Unscrew the capped needle and put the needle in a sharps container
• Do not store the KwikPen with the needle attached to prevent leaking, blocking the needle, and air from entering the KwikPen.

Step 17

• Replace the KwikPen cap.
• Do not store the KwikPen without the pen cap attached.