Tirzepatide (Mounjaro) UK: Complete Guide
Mounjaro (tirzepatide) is a next-generation dual-agonist medication that targets both GLP-1 and GIP receptors. it's approved in the UK for type 2 diabetes and weight management, with clinical trials showing up to 21% body weight loss.
Drug Class
Dual GLP-1/GIP agonist
Manufacturer
Eli Lilly
Private Cost
£200-£350/month
Avg Weight Loss
~21% body weight
2025 Update: NHS GP Prescribing Now Available
As of 2025, many NHS areas have enabled GPs to prescribe Mounjaro directly for weight management, without requiring a specialist referral. This can significantly reduce waiting times for eligible patients. Check with your GP about local availability.
Check full NHS eligibility criteriaWhat is Tirzepatide (Mounjaro)?
Tirzepatide, sold under the brand name Mounjaro, is a once-weekly injectable medication developed by Eli Lilly. it's the first "twincretin" or dual-agonist to be approved in the UK, meaning it activates two hormone receptors: GLP-1 and GIP.
This dual mechanism sets it apart from semaglutide (Ozempic/Wegovy), which only targets GLP-1. Clinical trials suggest this may lead to greater weight loss and blood sugar improvements than single-agonist medications.
Mounjaro was approved by the MHRA in 2023 for type 2 diabetes and subsequently for weight management in 2024. it's available on the NHS for eligible patients and through private prescription.
How Mounjaro Works
Tirzepatide works by mimicking two naturally occurring hormones that help regulate blood sugar and appetite:
- Reduces appetite and food cravings
- Slows gastric emptying (feel full longer)
- Stimulates insulin when blood sugar is high
- Reduces glucagon release
- Enhances insulin secretion
- May improve fat metabolism
- Could enhance weight loss effects
- Potential bone health benefits
UK Availability: NHS vs Private
- Available for type 2 diabetes (NICE approved)
- Approved for weight management (Nov 2024)
- 2025 update: GPs can now prescribe in many areas
- Availability varies by NHS trust/ICB
- £200-£350 per month (dose dependent)
- Available through online pharmacies & clinics
- Faster access than NHS waiting lists
- Ensure provider is GPhC registered
NHS Eligibility Criteria
For Type 2 Diabetes:
- Inadequate blood sugar control on current treatments
- Usually after trying metformin + other medications
For Weight Management:
- BMI 35+ (or 30+ with weight-related conditions)
- Referral to specialist weight management service
- Commitment to lifestyle changes (diet + exercise)
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Weight Loss Results
The SURMOUNT clinical trial programme showed impressive weight loss results with tirzepatide:
21%
Average body weight loss at highest dose (15mg)
1 in 3
Participants lost 25% or more of body weight
95%
Lost at least 5% of body weight
Important: These results are from 72-week clinical trials with lifestyle intervention. Individual results vary based on adherence, diet, exercise, starting weight, and individual metabolism. Tirzepatide works best when combined with sustainable lifestyle changes.
Mounjaro Dose Schedule
Mounjaro uses a gradual dose escalation over 16-20+ weeks to minimise side effects. Not everyone needs to reach the maximum dose.
| Timeline | Weekly Dose | Stage |
|---|---|---|
| Weeks 1-4 | 2.5mg | Starting dose |
| Weeks 5-8 | 5mg | Dose escalation |
| Weeks 9-12 | 7.5mg | Dose escalation |
| Weeks 13-16 | 10mg | Dose escalation |
| Weeks 17-20 | 12.5mg | Dose escalation (if needed) |
| Week 21+ | 15mg | Maximum maintenance dose |
Each pen contains 4 weekly doses. Your prescriber may keep you at a lower dose if you're achieving good results with tolerable side effects.
Mounjaro vs Wegovy vs Ozempic
How does tirzepatide compare to the semaglutide medications?
| Feature | Mounjaro | Wegovy | Ozempic |
|---|---|---|---|
| Active Ingredient | Tirzepatide | Semaglutide | Semaglutide |
| Mechanism | GLP-1 + GIP | GLP-1 only | GLP-1 only |
| Licensed For | T2D + Weight Loss | Weight Loss | T2D only |
| Weight Loss | ~21% | ~15% | ~5-6% |
| Max Dose | 15mg | 2.4mg | 1mg |
| Private Cost | £200-£350/mo | £150-£300/mo | £150-£250/mo |
Side Effects and Safety
Mounjaro's side effects are similar to other GLP-1 medications, mainly gastrointestinal. Most improve over time as your body adjusts.
- Nausea (most common, especially at start)
- Diarrhoea
- Vomiting
- Constipation
- Stomach pain / indigestion
- Decreased appetite
- Pancreatitis
- Gallbladder problems
- Hypoglycaemia (with other diabetes meds)
- Allergic reactions
- Kidney problems (if dehydrated)
Who Should NOT Take Mounjaro
- • Personal or family history of medullary thyroid cancer or MEN 2
- • Type 1 diabetes or diabetic ketoacidosis
- • History of pancreatitis
- • Pregnant, breastfeeding, or planning pregnancy
- • Severe gastrointestinal disease
- • Allergic to tirzepatide or any ingredients
Frequently Asked Questions
Related Guides
References & Sources
- Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. NEJM 2022.
- NICE Technology Appraisal: Tirzepatide for treating type 2 diabetes (TA924), 2023.
- MHRA. Mounjaro (tirzepatide) Summary of Product Characteristics.
- Eli Lilly. SURMOUNT Clinical Trial Programme results.
Medical Disclaimer
This information is provided for educational purposes only and is not intended as medical advice. Mounjaro is a prescription medication that requires assessment by a qualified healthcare professional. Always consult with your doctor or pharmacist before starting any weight loss or diabetes medication.
Last updated: December 2025
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