The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
When Does Mounjaro Patent Expire?
Mounjaro (tirzepatide) is protected by pharmaceutical patents that determine when generic versions can be manufactured and sold in the UK. The original patent for tirzepatide expires in 2033, meaning Eli Lilly has exclusive rights to produce and sell Mounjaro until that date. However, additional patents and market exclusivity periods may extend this timeline. Understanding these dates helps you anticipate future costs and availability of this prescription-only weight management injection in the UK.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Mounjaro Patent Timelines and Market Exclusivity
Mounjaro (tirzepatide) is manufactured by Eli Lilly and protected by multiple patents. The primary US patent expires in 2033, with similar protection periods expected in the UK and EU under comparable intellectual property law. However, Eli Lilly has also filed additional patents for formulation variants and delivery methods, which may extend exclusivity beyond 2033 in certain territories.
- US patent expiry: 2033 (primary patent)
- UK/EU protection: Expected to align with US dates, though UK patent law may differ post-Brexit
- Regulatory exclusivity: Separate from patent protection — may provide additional protection even after patent expiry
- Generic availability: Unlikely before 2032–2034 at the earliest, depending on patent challenges and regulatory approval timelines
These timelines apply to all Mounjaro KwikPen formulations and tirzepatide variants. Changes to NHS Nice guidance or private prescription costs may occur if generic versions become available, potentially reducing pricing over time.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
What This Means for UK Patients
Until generic tirzepatide becomes available (likely 2033 or later), Mounjaro remains a branded, patent-protected medication. This affects pricing: NHS access through tier 3 specialist services is free, but private prescriptions currently cost £129–£320 monthly depending on dose. Once the patent expires, generic tirzepatide may become available through private providers, potentially at lower cost — though NHS prescribing decisions will remain determined by NICE guidance and ICB commissioning rather than price alone. You can use our free BMI calculator to assess your current weight status and eligibility for this medication, and track any changes with our progress tracker over time.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Can I get generic tirzepatide now in the UK?
No. Mounjaro (tirzepatide) remains patent-protected until 2033 at the earliest. Generic tirzepatide is not yet available in the UK. All tirzepatide dispensed in the UK is the branded Mounjaro formulation. Check with your prescriber or pharmacist for current availability and costs.
Will generic Mounjaro be cheaper?
Yes, potentially. Once the patent expires and generic manufacturers can produce tirzepatide, prices typically fall. Generic versions may cost 20–50% less than branded Mounjaro. However, NHS prescribing is determined by NICE guidance, not price alone.
Does the patent expiry date affect NHS availability?
Not directly. NHS access to Mounjaro is determined by NICE guidance and local ICB (Integrated Care Board) commissioning, not patent status. Patent expiry may eventually lead to lower NHS procurement costs, but availability criteria are set independently.
Is tirzepatide the same as Mounjaro?
Tirzepatide is the active ingredient in Mounjaro. Currently, all tirzepatide available in the UK is sold as Mounjaro by Eli Lilly. Once the patent expires, other manufacturers may produce generic tirzepatide under different brand names.
How does Mounjaro compare to Wegovy for patent protection?
Wegovy (semaglutide) has different patent protection dates than Mounjaro. Semaglutide patents expire at different times. Both are prescription-only weight management injections, but Mounjaro is a dual GIP/GLP-1 agonist whereas Wegovy is a GLP-1 agonist only. Ask your GP which may be more suitable for your situation.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.