Weight management

Get to know Mounjaro (Tirzepatide) for weight loss: uses, side effects and how to use

Last reviewed:
February 16, 2024
Next review:
February 16, 2026

Mounjaro for weight loss has recently been licensed for use in the UK, so what is it and why is it being hailed as a breakthrough treatment for significant weight loss outcomes? We’ll explore Mounjaro, the easy-to-use Mounjaro KwikPens, and why it’s not just good for your waistline, but also your general health and overall quality of life.

What is Mounjaro?

Mounjaro is a revolutionary new once-weekly injectable weight loss medication that can help you lose weight. It contains tirzepatide; which reduces hunger pangs, slows gastric emptying and suppresses your appetite. When use alongside changes to diet and lifestyle, it’s been shown to help people lose up to 20% of their bodyweight.

How Mounjaro works

Mounjaro stimulates two different naturally occurring hormonal receptors: glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Other weight loss injections like Ozempic and Wegovy work on GLP-1 alone, whereas Mounjaro combines with GIP to increase the weight loss potential.

GLP-1 helps to regulate blood sugar levels, which in turn talks to the brain to make you feel less hungry and prevent cravings. It also slows down the emptying of the stomach to keep you feeling fuller for longer.

GIP regulates energy balance in brain and fat cells, enhancing the GLP-1 effect of suppressing your appetite and improving sugar control.

It also slows digestive tract movement slowing down the transit of food from the stomach to the small intestine. This slowing in gastric emptying can result in a prolonged feeling of fullness, fostering a reduction in overall food consumption.

Eligibility for treatment

Mounjaro for weight loss is suitable for individuals who are medically classed as overweight or obese and have a BMI in the range of 27-30 upwards (additional eligibility criteria applies). It’s not intended as a quick fix, but is designed to improve overall health and reduce the health-related risks associated with being overweight or obese.  

- You’re between 18 and 75 years old

- You have a BMI above 30, or have a BMI above 27 and a weight-related accompanying condition (eg high blood pressure or cholesterol, amongst others) that would benefit from weight loss

- You do not have diabetes (or pre-diabetes requiring treatment)   

- Meet all other clinical criteria, subject to your medical history

During the consultation stage we’ll ask you for more specific information to ensure Mounjaro is the right option for you.

How effective is Mounjaro?

Studies have shown that by week 72 people can achieve a 15% weight loss with 5mg, 19.5% weight loss with 10mg and 20.9% weight loss with 15mg (SURMOUNT-1 trial).

Understanding Mounjaro's side effects

Common side effects include nausea, headaches, stomach upsets (diarrhoea and vomiting) constipation, tiredness, acid reflux and indigestion symptoms, gallstones, dizziness, hair loss and reactions at injection sites.

Uncommon and rare side effects include increased heart rate, increased gastric enzyme levels, pancreatitis, angioedema and anaphylactic reactions.

We expect some common side effects to subside within the first few weeks, however if you experience any of the rarer side effects, you should stop the injections immediately and seek medical help.

How to use the Mounjaro KwikPen: a step-by-step guide

Before using your Mounjaro KwikPen, carefully follow these instructions. This guide will help you administer Mounjaro safely and effectively for your once-weekly injection.

When to take Mounjaro

Mounjaro is administered using the Mounjaro KwikPen, injected once a week on the same designated day. The injection is administered subcutaneously (under skin into fatty tissue), allowing flexibility in choosing the injection site—options include the stomach, thigh or upper arm. The KwikPen, a convenient pre-filled device, offers four doses, lasting one month. The specific dose administered correlates with the individual's unique weight loss journey.

Dosage instructions

Mounjaro comes in doses 2.5mg, 5mg, 7.5mg, 10mg and 15mg.

When initiating Mounjaro treatment, the starting dose is 2.5mg once weekly for the initial four weeks. Subsequently, the dosage is increased to 5mg once weekly for the next four weeks. As your treatment progresses, the dosage may be elevated each month, with the maximum dosage is 15mg. It's essential to recognise that the higher doses may not be necessary for everyone to achieve the desired effectiveness of Mounjaro and this decision will be taken by prescribers and patients together.

Storage information

Before the initial use, Mounjaro should be stored in a refrigerator within the temperature range of 2°C to 8°C. Once the pen is in use, it can be stored at room temperature (8 to 30°C) for up to 30 days. To maintain its effectiveness iIt's crucial to avoid freezing the medication.

Taking Mounjaro

Preparing to inject Mounjaro
  1. Take the KwikPen out of the fridge:
  • Keep the grey base cap on until you are ready to inject
  • Check the KwikPen label to ensure the correct medicine, dose and expiration date
  • Inspect the KwikPen for any damage

  1. Inspect the medicine:
  • Ensure the medicine is not frozen
  • Verify it is not cloudy and is colourless to slightly yellow
  • Confirm there are no particles in the medicine

  1. Choose your injection site:
  • Inject in the stomach (abdomen) or thigh on your own, or have another person inject in the back of your upper arm
  • Change (rotate) your injection site weekly

Administering Mounjaro
  1. Pull off the grey base cap:
  • Ensure the KwikPen is locked
  • Do not unlock until the clear base is on your skin and you are ready to inject
  • Discard the grey base cap in your household bin
  1. Place clear base on skin and unlock:
  • Press the clear base flat against your skin at the injection site
  • Unlock by turning the lock ring

  1. Press and hold for up to 10 seconds:
  • Press and hold the purple injection button for up to 10 seconds
  • Listen for two clicks: the first indicates the start and the second the completion of the injection
  • Your injection is complete when the grey plunger is visible

Disposing of your KwikPen and needles

Needles should be safely disposed into a sharps bin. You may be able to contact your local council to take the sharps bin away to be destroyed (there may be a charge for it), or take it to your nearest pharmacy

Used injection pens shouldn't be disposed in normal household waste and can be taken to local pharmacy for safe disposal

Do not recycle used sharps bins. You can always ask us if you need a replacement

Ready to achieve sustainable weight loss and embrace a healthier lifestyle? Discover the groundbreaking weight loss treatment offered by Phlo Clinic—the key to unlocking your weight management success. The Mounjaro KwikPen is an alternative to non-reversible weight loss surgeries and we make it easy to pay-as-you-go with no hidden fees.

The alternative to non-reversible weight loss surgeries. Pay-as-you-go with no hidden fees.

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