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
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Finding Best Value Mounjaro in the UK
If you're looking for best value Mounjaro in the UK, you need to understand both NHS and private access routes, which have very different costs and waiting times. Mounjaro (tirzepatide) is a prescription-only weight loss injection licensed in the UK for adults with a BMI of 30 or above, or 27 or above with weight-related health conditions. The cost and availability vary significantly depending on whether you access it through the NHS or private prescribing. This guide explains your options to help you find the most cost-effective route for your situation.
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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.
NHS vs Private: Where to Access Mounjaro
NHS Access: Mounjaro is available through NICE-approved NHS specialist weight management services (tier 3/4), but access is limited and regional. You'll need a GP referral to your local specialist weight management service. Many areas have significant waiting lists—sometimes 12 months or longer. If you do gain NHS access, Mounjaro is provided free at the point of care, but this route typically involves lengthy assessment processes and may require attempts at other interventions first. Not all ICBs (Integrated Care Boards) have equal provision.
- NHS cost: Free if approved, but limited availability
- Access: Through GP referral to specialist services
- Timeline: Often 6–18 months waiting
- Eligibility: BMI ≥30 or ≥27 with comorbidities
Private Access: Private prescribing through GPhC-registered online pharmacies offers faster access without NHS waiting lists. You complete an online clinical assessment with a UK-licensed prescriber, who assesses suitability before issuing a prescription. Private Mounjaro typically costs between £129–£320 per month depending on your dose and provider, with costs varying significantly across different services.
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No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Maximising Value: Doses and Cost-Effectiveness
Best value doesn't always mean lowest price—it means the dose that delivers clinical benefit for your cost. Mounjaro starts at 2.5 mg (£129–£150/month) and escalates weekly to a maximum of 15 mg (£280–£320/month). Clinical trials showed average weight loss of 15–21% across doses, with results varying individually. Many people find therapeutic benefit at 5–10 mg doses, where costs are lower than maximum dose. Our free GLP-1 weight loss calculator can help you estimate potential weight loss at different doses based on your starting weight. Before committing to treatment, use our BMI calculator to confirm your eligibility and discuss dose strategy with your prescriber to balance cost against expected outcomes.
- 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.
Is Mounjaro cheaper on the NHS or privately?
If approved by NHS specialist services, Mounjaro is free. However, NHS access has long waiting lists in many areas and availability varies by region. Private access costs £129–£320/month depending on dose but offers faster access without waiting. For some people, paying privately for faster access offers better overall value, especially if weight loss is time-sensitive for health reasons.
What's the lowest effective dose of Mounjaro for weight loss?
Clinical trials showed measurable weight loss at all doses from 5 mg upward. Many people find good results at 5–7.5 mg, where monthly costs are lower (typically £150–£200). Your prescriber will recommend dose escalation based on your individual response and tolerance, balancing efficacy against cost.
Can I switch between NHS and private Mounjaro?
Generally, no. If you start private treatment, you cannot usually transfer to NHS provision mid-treatment. If you gain NHS approval while already receiving private treatment, discuss with your NHS team—you may need to pause private treatment before NHS initiation. Plan your route carefully before starting.
Does Mounjaro work out cheaper than Wegovy for weight loss?
Both are prescription-only with similar private costs (£120–£320/month). Mounjaro is a dual GIP/GLP-1 agonist; Wegovy is GLP-1 only. Clinical data suggests Mounjaro may deliver slightly greater average weight loss (15–21% vs ~15% for Wegovy), potentially offering better value per kilogram lost—but individual results vary significantly.
What makes Mounjaro good value compared to other weight loss options?
Mounjaro is a once-weekly injection (easier than daily alternatives like Saxenda), and clinical trials showed significant weight loss when combined with lifestyle changes. Compared to bariatric surgery (£5,000–£15,000+), even 12 months of private Mounjaro (£1,500–£3,800) may offer better value. Results vary, so discuss expected outcomes with your prescriber before starting.
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.