What Is Mounjaro (Tirzepatide)? A Complete Guide for UK Patients

What Is Mounjaro?

Mounjaro is the brand name for tirzepatide, a prescription injection used for weight management and type 2 diabetes. Manufactured by Eli Lilly, it was approved by the MHRA for use in the UK and has quickly become one of the most talked-about weight loss treatments available.

Unlike older weight loss medications, Mounjaro works on two hormone pathways simultaneously — GLP-1 and GIP — which is why it's often called a "dual-agonist" or "twincretin."

How Does Mounjaro Work?

Mounjaro mimics two naturally occurring gut hormones:

• GLP-1 (glucagon-like peptide-1): Reduces appetite, slows stomach emptying, and helps regulate blood sugar.
• GIP (glucose-dependent insulinotropic polypeptide): Enhances insulin secretion and may also influence fat metabolism.

By targeting both pathways, Mounjaro delivers more significant appetite reduction and weight loss than single-agonist treatments like semaglutide (Ozempic/Wegovy).

What Results Can I Expect?

In the landmark SURMOUNT-1 clinical trial, participants on the highest dose of tirzepatide (15mg) lost an average of 22.5% of their body weight over 72 weeks. Even the lowest dose (5mg) produced an average weight loss of 15%.

For context, if you weigh 100kg, that could mean losing 15-22kg over approximately 18 months.

Results vary depending on:

• Your starting weight and BMI
• Diet and physical activity levels
• Which dose you're prescribed
• How consistently you take the medication

Mounjaro Dosing Schedule

Mounjaro uses a dose escalation approach to minimise side effects:

Your prescriber will adjust the dose based on your response and tolerability.

Common Side Effects

Like all GLP-1 medications, Mounjaro can cause gastrointestinal side effects, especially when starting or increasing the dose:

• Nausea (most common, usually mild)
• Diarrhoea
• Decreased appetite (this is partly how it works)
• Constipation
• Injection site reactions

Most side effects are temporary and improve as your body adjusts. Taking Mounjaro with food and staying hydrated can help.

Who Is Mounjaro Suitable For?

In the UK, Mounjaro for weight management is typically prescribed to adults who:

• Have a BMI of 30 or above (obese), or
• Have a BMI of 27 or above with at least one weight-related health condition (high blood pressure, type 2 diabetes, high cholesterol)
• Have tried diet and exercise without sufficient results

Mounjaro is not suitable if you are pregnant, breastfeeding, have a personal or family history of medullary thyroid carcinoma, or have multiple endocrine neoplasia syndrome type 2.

How to Get Mounjaro in the UK

Mounjaro is a prescription-only medicine (POM), which means you cannot buy it over the counter. There are two main routes:

1. NHS: Currently limited availability. Your GP may be able to prescribe it through specialist weight management services.
2. Private online pharmacy: Services like Roots Pharmacy offer convenient online consultations. You complete a medical questionnaire, a qualified prescriber reviews it, and if appropriate, your prescription is dispensed and delivered to your door.

At Roots Pharmacy, the process takes as little as 24-48 hours from consultation to dispatch.

Mounjaro vs Ozempic (Semaglutide)

Both are GLP-1 based treatments, but there are key differences:

Clinical data suggests Mounjaro produces greater weight loss on average, likely due to its dual-hormone mechanism.

Is Mounjaro Safe?

Mounjaro has been through extensive clinical trials involving thousands of participants. It is approved by the MHRA (UK), FDA (US), and EMA (EU). Like any prescription medication, it carries risks that your prescriber will assess during consultation.

Important: Always obtain Mounjaro from a legitimate, GPhC-registered pharmacy. Counterfeit weight loss injections have been found in the UK and can be dangerous.

Getting Started with Roots Pharmacy

If you're considering Mounjaro, starting is straightforward:

1. Complete our free online consultation — answer questions about your health, medical history, and weight loss goals.
2. Prescriber review — a qualified clinician reviews your answers and medical suitability.
3. Prescription dispensed — if approved, your medication is dispatched via tracked Royal Mail delivery.

Our prescribers are thorough and prioritise your safety. Not everyone will be suitable, and that's okay — your health always comes first.