Mounjaro Weight Loss Injections

In stock
  • Proven to help you lose up to 22.5% body weight*
  • Controls appetite, food noise and cravings
  • Once-weekly injection with the easy-to-use KwikPen
  • No costly extras or subscriptions
  • Fast, discreet delivery
  • 100% UK-based pharmacy
  • Free advice and support
  • We're rated 4.9 out of 5

Mounjaro Injection - UK Weight Loss Treatment Available Online

£179.99

Mounjaro (tirzepatide) is a weekly injectable medication that can help you lose weight by activating GIP and GLP-1 receptors. Once activated, these receptors help to control your appetite by tricking your brain into thinking that you aren’t hungry.  These also slow down your digestion so that you feel fuller for longer.

Mounjaro was originally developed as a treatment for type 2 diabetes, but has now been approved to help with weight management. Treatment starts with a low 2.5mg dose of Mounjaro, and your pharmacist will gradually increase the dose. This gives your body the chance to adjust to the treatment, which can help to minimise side effects. Your maximum dose will be a careful balance of achieving the desired effect (weight loss) while keeping side effects to a minimum.

The Mounjaro KwikPen makes administration simple - it’s been designed to make self-injection as easy as possible.

Who Is Mounjaro Weight Loss Injections Suitable For?

Suitable for pregnancy?No
Suitable for breastfeeding?No
Consultation required?Yes

Mounjaro (Tirzepatide) Summary

What Are Mounjaro Injections?

Mounjaro is a weight loss medication that’s taken as a weekly injection. Mounjaro works by acting on the hormones that control your hunger, reducing your appetite and helping you feel fuller for longer. The medication is often prescribed for adults who have type II diabetes or other weight-related health conditions.

Can I Use Mounjaro?

If you haven’t had pancreatitis or serious digestive issues, you may be able to take Mounjaro. However, Mounjaro could interact with other medications and may cause some side effects, so it’s essential you book a consultation with a licensed clinician before taking the weight loss injections.

Mounjaro Weight Loss Results

Studies have shown that you could lose up to 22.5% of your body weight after 72 weeks of Mounjaro treatment. So, if you weigh 100kg (15st 10lbs) at the start of treatment, you could lose 22.5kg (3st 7lbs) within 18 months.

How Does Mounjaro Work?

Mounjaro works by mimicking two hormones that are naturally produced by your gut. These hormones trigger receptors in your body that tell your brain that you’re full. By mimicking these hormones, Mounjaro may reduce your appetite and help you feel fuller for longer so that you eat less.

Mounjaro comes in specially designed ‘Kwikpens’, making it easy for you to inject the medication at home.

Can I Switch From Mounjaro to Another Weight Loss Jab After I've Started?

Yes, this is possible under medical supervision. While both medicines help with weight loss and blood sugar control, they work slightly differently and have different dosing schedules.

You cannot alternate between the two medications or inject both medications at the same time. However, you can make a permanent switch from one to the other.

Find out more by reading our switching guide here.

*Based on patients using Mounjaro 15mg during the 72-week SURMOUNT-1 trial

How To Use Mounjaro

The usual starting dose of Mounjaro is 2.5mg per week. Once your body has adjusted to the medication, your doctor will slowly increase the amount of Mounjaro you take to find the dose that best balances effectiveness with managing side effects. The maximum recommended dose of Mounjaro is 15mg per week.

Ingredients

The main active ingredient in Mounjaro is tirzepatide. This is the medication that mimics your hormones and helps reduce your appetite.

The other ingredients contained in Mounjaro are sodium phosphate dibasic heptahydrate, benzyl alcohol, glycerol, phenol, sodium chloride, sodium hydroxide, concentrated hydrochloric acid and water for injections.

Side Effects

Like all medications, Mounjaro may cause some side effects. If you take Mounjaro, you could experience nausea, stomach pain, constipation, indigestion and diarrhoea. You may also feel dizzy or lightheaded and could feel more tired than usual.

In very rare cases, Mounjaro could cause more serious side effects such as an allergic reaction, pancreatitis or gallbladder disease.

Warnings

Mounjaro is not suitable for you if you have a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2), or are allergic to tirzepatide or any other of the ingredients.

You should also not take Mounjaro if you are pregnant, planning to become pregnant or breastfeeding. It may harm your baby.

You should let your doctor know if you have a history of pancreatitis, gallbladder disease, or kidney problems, as these mean that Mounjaro may not be right for you. If you’re taking oral contraceptives, you should note that Mounjaro can make them less effective, so you should add a non-hormonal method and/or barrier method, such as condoms.

Age and Complex Health Conditions

This service may not be suitable for all patients, including some older adults or those with complex health conditions.

What Is Changing With the Mounjaro Kwikpen?

Eli Lilly has confirmed that updated Mounjaro KwikPens will begin appearing in the UK from April 2026.

The updated device still works in the same way. The change affects how the pen works internally, but not how you use it.

The new pens will still:

  • Be disposable after use
  • Contain 4 weekly injections

The main difference is how the plunger moves inside the pen. With each dose, it now moves further down the pen, reaching the very end after the 4th dose. This makes it clearer when the pen is empty.

This design improvement helps reduce the amount of visible leftover liquid and makes it easier to see when the pen has reached its final dose.

The updated design is intended to:

  • Improve overall usability
  • Provide clearer visual dose progression
  • Make it easier to recognise when the pen is empty

Why Is the Mounjaro Pen Update Important?

Previously, some patients were unsure when their KwikPen was fully used, due to a small amount of liquid remaining after the final dose.

The update is all about making things simpler and safer for patients. The new design aims to reduce confusion by:

  • Making dose selection clearer
  • Helping reduce the chance of mistakes
  • Providing a clearer visual indicator of when the pen is empty and should be discarded

It’s based on feedback from people who use the pen regularly.

Has Anything Changed With the Medication Itself?

No, the medication inside the pen is exactly the same. You’re still getting the same active ingredient (tirzepatide) in the same strengths. Only the pen design has changed.

What Do I Need to Do Differently?

Nothing changes in how you use your Mounjaro pen.

  • Continue taking one dose per week as prescribed
  • Each pen still contains 4 fixed doses only
  • Dispose of the pen after your 4th dose
  • Do not try to use any remaining liquid after your final dose

Is the New Mounjaro KwikPen Safe?

Yes, when used correctly, it’s just as safe as the previous version. In fact, the updates are designed to help you use it more accurately and confidently.

What Does the New Mounjaro KwikPen Look Like?

You may notice some visual changes with the updated design:

Image of modified mounjaro kwikpen
Image of used modified mounjaro kiwkpen

Photo credit: Eli Lilly UK

Plunger Position: The plunger now sits further down in the cartridge when the pen is unused.

Extended Plunger: A new internal component has been added behind the plunger, extending its length. This is shown in the Mounjaro KwikPen Guide to Parts section in the Instructions For Use (IFU).

Remaining Medicine: After the 4th dose, the plunger will be near the end of the pen, clearly indicating the pen is ready to be discarded.

Will the New Pen Change How You Inject Mounjaro?

No. The injection process stays exactly the same. You’ll continue using your pen in the same way, with one dose per week.

Will I Receive the New Mounjaro KwikPen in the UK?

From April 2026, patients in the UK may receive either the previous or updated design depending on pharmacy stock and supply. Over time, the newer version is expected to become standard. Both versions are safe, approved, and work in the same way. You do not need to request a specific version.

What’s Happened to the “Golden Dose”?

With the previous KwikPen design, a small amount of liquid sometimes remained after completing 4 doses. This was referred to colloquially as the “golden dose”.

However, the pen was always designed to deliver 4 fixed doses only. The remaining liquid allowed for priming and was not an additional prescribed dose.

The updated pen makes this clearer. After your 4th dose, the pen is empty and should be discarded.

Do not try to use any leftover liquid.

Do I Need to Change How I Prime the Pen?

No, priming instructions remain the same.

Will I Need Training On the New Pen?

No, the pen is used in the same way as before.

Mounjaro Pricing Update

On the 1st September 2025, Eli Lilly, the company that manufactures Mounjaro, decided to increase the price of the medication. This price rise will affect all regulated suppliers of Mounjaro.

If you’re concerned about how the cost increase will affect you, speak to a member of our team about alternative treatment options.

Mounjaro Weight Loss Injections reviews

Mounjaro Weight Loss Injection FAQs

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Read our Mounjaro guides

Our expert clinical team have published a range of reviewed and clinically-sourced information on Mounjaro to ensure our patients have all the information they need on their weight loss journey.

What Is Mounjaro & How Does It Work For Weight Loss

How to use the Mounjaro KwikPen

5 Things to Know Before Taking Mounjaro

What Do Our Reviewers Say About Mounjaro?

How to Manage Common Side Effects of Mounjaro

Mounjaro Side Effects & How To Decrease Them

How Long Does It Take to See Mounjaro Weight Loss Results?

Common Mounjaro Myths And Facts: What You Need To Know

When & How To Move To A Mounjaro Maintenance Dose

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Daniel Hurley
Reviewed by Daniel Hurley