What is Mounjaro (Tirzepatide)?
Mounjaro is the first and only dual GIP/GLP-1 receptor agonist, representing a new class of medicines for weight management.
Overview
Mounjaro contains the active ingredient tirzepatide. It was originally approved for type 2 diabetes but has shown remarkable results for weight loss. In late 2023, it was approved in the UK for weight management under the brand name Mounjaro.
It is a weekly injection that you administer yourself using a pre-filled pen.
How Does It Work?
Mounjaro mimics two natural hormones in the body:
- GLP-1 (Glucagon-like peptide-1): Reduces appetite and slows stomach emptying.
- GIP (Glucose-dependent insulinotropic polypeptide): Works synergistically with GLP-1 to further improve how the body breaks down sugar and fat.
This "dual agonist" approach is what makes Mounjaro more effective than single-hormone medications like Wegovy or Saxenda in clinical trials.
How Effective Is It?
In the SURMOUNT-1 clinical trial, participants taking the highest dose (15mg) of Mounjaro lost an average of 22.5% of their body weight over 72 weeks.
For a person weighing 100kg (15st 10lb), that equates to a loss of 22.5kg (3st 7lb).
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22.5%
Avg. Weight Loss
Weekly
Injection
Who Is It For?
In the UK, Mounjaro is typically prescribed for adults with:
- A BMI of 30 or higher (obesity).
- A BMI of 27 or higher (overweight) who also have a weight-related health condition such as pre-diabetes, high blood pressure, or high cholesterol.
Medical References & Sources
Last Medically Reviewed: April 2026
At a Glance
- Active Ingredient
- Tirzepatide
- Type
- Weekly Injection
- Class
- Dual GLP-1/GIP
- Avg Loss
- Up to 22.5%
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