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 in the UK?
Mounjaro (tirzepatide) currently has patent protection in the UK that is expected to expire in 2031, though the exact date depends on patent extension decisions by Eli Lilly. Understanding patent timelines matters if you're considering this prescription weight management option. Generic versions may become available after patent expiry, but that doesn't affect your access today. Right now, Mounjaro remains available through NHS specialist services and private prescribing in the UK — the same applies to Wegovy (semaglutide), which has its own separate patent timeline.
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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 vs Wegovy — Patent and Availability Context
Mounjaro (tirzepatide) is manufactured by Eli Lilly and currently benefits from patent protection expected to last until approximately 2031 in the UK. This patent covers the active ingredient and specific formulations. Wegovy (semaglutide), made by Novo Nordisk, has a separate patent timeline — semaglutide patents are expected to expire later, around 2033–2034 depending on regulatory decisions.
Both medications are prescription-only and require a clinical assessment before being prescribed. The KwikPen delivery device used by Mounjaro also has separate patent protection. Once a patent expires, generic manufacturers can apply to produce tirzepatide, but this typically takes 12–24 months for a generic version to reach the market following patent loss. Until then, branded Mounjaro remains the only available form in the UK.
Currently, both medications are available through NHS tier 3 specialist weight management services (subject to regional funding decisions) and through private online prescribing from UK-licensed prescribers. Patent expiry does not change availability today — it only affects future generic access and potential pricing.
Clinically BackedWeight Loss
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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.
Suitability, Access, and Your Next Steps
Choosing between Mounjaro and Wegovy is a decision made by you and your prescriber based on individual health factors, not patent timelines. Our free GLP-1 weight loss calculator can help you understand potential outcomes at different doses of either medication, and our BMI calculator can confirm your eligibility category. Both medications work as dual or single GLP-1 pathway activators — Mounjaro uses a dual GIP+GLP-1 mechanism, while Wegovy activates GLP-1 alone. Clinical trial data shows both deliver meaningful weight loss when combined with lifestyle changes, though individual results vary.
Your GP can refer you to NHS specialist services, or you can access private prescribing following an online assessment. Patent considerations are unlikely to affect your decision — focus instead on which medication your prescriber recommends based on your health profile, side effect tolerance, and treatment goals.
- 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.
Does Mounjaro's patent expiry in 2031 mean I can't get it now?
No. Mounjaro remains fully available in the UK right now through NHS specialist services and private prescribing. Patent expiry only affects future generic availability — it doesn't change current access. You can still be prescribed Mounjaro today if eligible following a clinical assessment.
Will generic tirzepatide be cheaper than Mounjaro?
Once the patent expires and generic versions are approved, they will typically cost less than branded Mounjaro. However, this is usually 12–24 months after patent loss. On the NHS, pricing is controlled through national agreements, so savings may differ from private costs.
Is Mounjaro or Wegovy better for me?
That's a question for your prescriber. Both are prescription-only and require clinical assessment. Mounjaro uses a dual GIP+GLP-1 mechanism, while Wegovy is GLP-1 only. Your GP or weight management specialist will recommend based on your individual health, medical history, and suitability factors.
Can I get Mounjaro on the NHS right now?
Yes, through NHS tier 3 specialist weight management services. Access varies by region — ask your GP for a referral. Private online prescribing is also available if you meet eligibility criteria (BMI ≥30 or ≥27 with weight-related health conditions).
Will I need to switch medications when Mounjaro goes generic?
Not necessarily. If Mounjaro is working well for you, you'll likely continue with it. Generic tirzepatide would be the same active ingredient — your prescriber may switch you to a generic version once available if it offers cost savings, but this is your choice in consultation with them.
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.