Mounjaro Weight Loss Injections (Tirzepatide)

About Mounjaro (Tirzepatide)

Medication NameMounjaro Pen

Active IngredientTirzepatide

Medication formPre-filled Injection

Used to treatType 2 Diabetes
Weight Loss

Available dosagesPre-filled, single-dose pen delivers doses of 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg or 15mg

Other names by which this medication is known Mounjaro Weight Loss Pen
Mounjaro Weight Loss Injection

Common side effects
Nausea, diarrhoea, vomiting, decreased appetite, indigestion, allergic reaction, constipation, stomach pain, tiredness, increased pulse, dizziness, feeling bloated, belching, gas and heartburn.

Who is this medication suitable forAdults over the age of 18 with:
– BMI over 30
– BMI over 27 with weight-related medical problems

Do you need a prescription for it?Yes

How should it be used?Use once a week on the same day each week. Each pen contains 4 doses.

Patient Information Leaflet Mounjaro Patient Information Leaflet

Mounjaro Instructions For Use Leaflet

What is Mounjaro?
Mounjaro is a new weight loss drug authorised for weight loss and management in the UK. Initially a type 2 diabetes treatment, it contains the active ingredient Tirzepatide. When taking Mounjaro for weight loss, patients use one Mounjaro pen per week and must follow a diet and exercise plan for best results.
How do Mounjaro weight loss injections work?
Mounjaro is a weekly weight loss injection that contains the active ingredient Tirezepatide, which imitates two hormones: glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). These hormones slow digestion, so food takes longer to pass through your digestive system. They also reduce your appetite, so you feel fuller for longer and eat less.
Who can take Mounjaro for weight loss?
Mounjaro weight loss injections are suitable for those who meet the following Mounjaro BMI requirements:

Body mass index (BMI) over 30
BMI over 27 who have also been diagnosed with weight-related medical problems, including type 2 diabetes, high cholesterol, obstructive sleep apnea and high blood pressure.

If you have any of the following conditions, talk to your GP or pharmacist before using Mounjaro:

Severe problems with food digestion or food remaining in your stomach for longer than normal (including severe gastroparesis)
Pancreatitis
Diabetic retinopathy or macular oedema

If you use a sulphonylurea (diabetes medicine) or insulin, be aware low blood sugar (hypoglycaemia) can occur. Your doctor or pharmacist may need to change your dose of these other medicines to reduce this risk.
Mounjaro Dosage Options
Mounjaro injections for weight loss come in different dose options. The starting dose of Mounjaro is 2.5mg, and if appropriate, you’ll move up to 5mg after 4 weeks. Once you have settled on 5mg, we will work with you to decide if you need to increase to a higher dose of 7.5mg, 10mg, 12.5mg or 15mg. Each time your dose increases, you need to remain on it for 4 weeks before increasing.

How much does Mounjaro cost per month?
Mounjaro injection pens vary in price depending on where you purchase them. At Click2Pharmacy, we aim to make weight loss treatment as accessible as possible and are committed to fair pricing.

Click2Pharmacy Mounjaro Asda Mounjaro Boots Mounjaro Oxford Online Pharmacy Mounjaro Simple Online Pharmacy Mounjaro SheMed Mounjaro Numan Mounjaro Health Express Mounjaro

2.5mg£145.99£168.97£177.30£149.99£159.99£199.00£249.00£179.99

5mg£173.99£198.97£222.00£189.99£179.99£299.00£249.00£199.99

7.5mg£222.99£284.97£268.00N/A£239.99£299.00£269.00£249.99

10mg£249.99£278.97£303.00£279.99£279.99£299.00£269.00£279.99

12.5mg £269.99 £288.97 £315.00N/A £289.99 £349.00 £299.00 £299.99

15mg £288.99 £298.97 £335.00 £299.99 £299.99 £349.00 £299.00 £309.99

Prices as shown online on 01/09/2025. We take no responsibility for the accuracy of this information and advise you to complete your own cost comparison for the best value for money.
How effective is Mounjaro for weight loss?
Clinical studies have shown that Mounjaro can lead to a 15% weight loss in patients after 9 months of taking it for weight loss.
When announcing the authorisation of Mounjaro pens for weight loss management in the UK, the MHRA shared clinical trial results over 16 months showing up to 22.5% weight loss in patients taking Tirzapatide.

How much weight do you lose on Mounjaro in the first month?
Mounjaro starts working immediately, but initial weight loss in the first month is often small as your body adjusts to the medication. This is completely normal and part of the process.
Studies show that you may lose up to 4% of your body weight during the first 4 weeks, with further weight loss up to 72 weeks. For healthy weight loss, Mounjaro should be combined with a reduced-calorie diet and regular physical activity. As you continue treatment, you’ll likely see more consistent progress over time.
How to Use Mounjaro Weight Loss Injections

Where should I inject Mounjaro?
Mounjaro should be injected under the skin (subcutaneously) in your abdomen, thigh, or upper arm. Use a new injection site each week to avoid irritation. If you use the same limb or your abdomen, use a different spot within the same area.
If you’re unsure how to inject or need guidance, check the Mounjaro Instructions For Use included with your pen or reach out to your doctor or pharmacist for help.

How To Inject Mounjaro
Mounjaro weight loss injections should be injected under the skin of your stomach, upper leg or upper arm:
Preparing to Inject Mounjaro

Wash your hands.
When ready, pull off the base cap.
Wipe the inner seal and choose a new pen needle. To help prevent infections, you should use a new pen needle for each injection.
Push the capped needle onto the pen and twist on until tight.
Pull off both the needle shield and the inner needle shield and move to one side.
Turn the knob until you hear two clicks, and the line is shown in the dose window.
Hold your pen with the needle pointing up and tap the side of the cartridge holder to collect any air bubbles at the top.
Prime your pen by pushing the dose knob in until it stops, releasing some medicine into the air, and slowly count to 5. The 0 icon should be shown in the window.

Injecting Mounjaro

Prepare by cleaning the injection site using an alcohol swab or soap and water.
Turn the dose knob until it shows the 1 icon, and it stops.
Insert the needle into your skin and push the dose knob until it stops.
Slowly count to 5 while holding down the dose knob.
Wait until the 0 icon is showing in the dose window before removing the needle.
Use a gauze pad or cotton wool if needed and apply pressure to stop bleeding.
Replace the outer needle shield and unscrew the capped needle.
Throw away your needle in the sharps bin.
Replace the cap on the pen.

What happens if my Mounjaro pen gets jammed?
A completely stuck Mounjaro pen is quite rare, and what many people experience as “jamming” is actually the pen’s built-in safety mechanism doing its job.
If your pen feels resistant, this is often normal and part of the design that ensures safe, precise dosing. However, if you have problems with your pen, there are several simple checks you can perform yourself to fix a jammed Mounjaro pen and resolve the problem.
What are the side effects of Mounjaro?
Like any other medication, you may experience side effects from taking Mounjaro, and everyone’s experience differs. If you are concerned about any side effects of Mounjaro weight loss injections, speak to your pharmacist or GP before starting treatment.
Common Mounjaro Side Effects

Nausea
Diarrhoea
Decreased appetite
Vomiting
Constipation
Indigestion
Stomach pain
Allergic reaction (rash, itching or eczema)
Stomach bloating
Acid reflux or heartburn
Feeling tired
Increased pulse

Mild stomach issues from taking Mounjaro injections for weight loss usually improve in time. If you experience nausea, users have found the following has helped:

Eat smaller meals, or splitting 3 daily meals into 4 or more
Avoid foods high in fat
Eat blander, less rich foods, such as toast, rice or crackers
Make sure you stop eating when you feel full

If nausea continues after following these guidelines, speak to your doctor or pharmacist.
Uncommon Mounjaro Side Effects

Low blood sugar (hypoglycaemia)
Gallstones
Injection site pain

Serious Mounjaro Side Effects

Inflammation of the pancreas (pancreatitis)
Low blood sugar (hypoglycaemia)
Serious allergic reactions
Kidney failure
Severe stomach problems
Vision changes
Gallbladder problems

If you have a kidney-related health condition and experience diarrhoea, nausea or vomiting after using Mounjaro, ensure you increase your fluid intake to reduce the risk of dehydration and contact your GP, pharmacist or an out-of-hours doctor.
These are not all the possible side effects of Mounjaro. You should review the Patient Information Leaflet before starting the treatment so you are familiar with all potential side effects.
Reporting Side Effects
If you experience any side effects, even if they aren’t included in the patient information leaflet, report them to your doctor, pharmacist or nurse. You can also report side effects directly via the Yellow Card Scheme.
Alternatives to Mounjaro
If you’re exploring treatment options for weight management or type 2 diabetes, there are several proven medications available instead of Mounjaro.
At our weight loss clinic, we understand that finding the right medication is a personal journey, which is why we offer trusted options like Wegovy and Saxenda.
If you’re wondering about the differences between these medications:

Wegovy vs Mounjaro vs Ozempic: Wegovy and Ozempic contain the active ingredient semaglutide, whereas Mounjaro contains tirzepatide. Wegovy and Mounjaro are both licensed as a weight loss medication, whereas Ozempic is not.
Mounjaro vs Saxenda: Mounjaro is a once-weekly injection of between 2.5-15mg of tirzepatide, whereas Saxenda is a daily injection of between 0.6-3mg of liraglutide.

If you are looking for alternatives to using weight loss injections,  you might be interested in weight loss pills such as Orlistat, Alli Weight Loss Capsules or Xenical Capsules.
Important Information

If you are taking the contraceptive pill, you will need to use a barrier method or switch to a non-oral contraceptive for 4 weeks after starting Mounjaro and for 4 weeks after each increase in dose.
Keep Mounjaro pens and disposal containers out of sight and reach of children.
Do not use after the expiry date.
Do not use your Mounjaro pen if you notice it is damaged or the medicine is cloudy, discoloured or has particles in it.
Mounjaro is not suitable if you are allergic to the active ingredient in Mounjaro (tirzepatide) or any of the other ingredients in this medicine.
KwikPens cannot be recycled. Used pen needles need to be disposed of in a sharps disposal container immediately after use, and you will need to check with your local council for instructions on how to dispose of your sharps container.
Empty KwikPens can go into household waste or a sharps disposal container. You can return any unused medicine to any pharmacy in England for safe disposal.
When starting treatment with Mounjaro, you might sometimes lose fluids or become dehydrated due to side effects like vomiting, nausea, or diarrhoea. To prevent dehydration, make sure to drink plenty of fluids.