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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Mounjaro and Fibromyalgia — UK Access and Cost
Fibromyalgia often makes weight management more difficult due to fatigue, pain, and reduced mobility. Some people living with fibromyalgia are exploring Mounjaro (tirzepatide) as a potential support for weight management, alongside lifestyle adjustments. This guide explains how to access Mounjaro in the UK, the costs involved, and what the eligibility criteria are. We've included practical information about both NHS and private routes so you can understand your options clearly.
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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.
How Much Does Mounjaro Cost and How Do I Access It?
In the UK, Mounjaro (tirzepatide) is a prescription-only weight management injection available through two main routes: NHS specialist services and private prescription through GPhC-registered online providers.
NHS access: Mounjaro was approved by NICE for use within NHS specialist weight management services. However, NHS availability depends on your local Integrated Care Board (ICB) and can involve significant waiting times—sometimes months or longer. You'll need referral from your GP to a tier 3 or tier 4 specialist weight management service.
Private access: Through private online consultations with UK-licensed prescribers, Mounjaro typically costs between £129–£320 per month depending on your dose. Costs rise as you increase dose (starting at 2.5 mg, titrating to a maximum of 15 mg once weekly). Private providers offer faster access but require payment upfront.
Both routes require a clinical assessment to confirm suitability. Your health history, current medications, and weight-related health conditions will be reviewed.
Clinically BackedWeight Loss
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.
NHS vs Private: Which Route Is Right for You?
The NHS route is free but involves referral, specialist assessment, and potential waiting lists. It's the appropriate choice if you're already registered with a GP and willing to wait. Private prescribing is faster and doesn't require NHS referral, but you pay per dose. An online consultation with a UK prescriber typically takes 20–30 minutes; the prescriber reviews your medical history, current conditions (including fibromyalgia), and any medications you're taking.
Both Mounjaro and Wegovy (an alternative GLP-1 injection) require regular clinical monitoring. If you have fibromyalgia and significant fatigue, discuss this openly during your consultation—it affects how you'll manage injections and any side effects. Use our free BMI calculator and GLP-1 weight loss calculator above to understand your starting point and explore potential outcomes at different doses.
Once prescribed, your Mounjaro KwikPen is dispensed by a regulated pharmacy. You inject once weekly into your stomach, thigh, or upper arm. Initial doses are 2.5 mg, increasing by 2.5 mg every 4 weeks until you reach your target dose or maximum tolerance. Side effects—nausea, constipation, or diarrhoea—are common initially but often ease over time. If fibromyalgia pain or fatigue worsens, contact your prescriber immediately.
Cost per injection ranges from £129 (lower doses) to £320 (15 mg maximum dose). A starter pack of 4 injections (one month's supply) at 2.5 mg typically costs around £129–£150. If you move up through dose titration, costs increase proportionally. Some private providers offer payment plans or discounts for longer-term commitments.
- 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 Mounjaro on the NHS if I have fibromyalgia?
Yes, if you meet eligibility criteria: BMI of 30 or above, or 27–29.9 with weight-related health conditions. Fibromyalgia itself doesn't automatically qualify you, but if it contributes to other conditions (like type 2 diabetes or high blood pressure), that may support your case. Ask your GP about referral to specialist weight management services in your area.
How long does the private prescription process take from consultation to first injection?
Typically 3–7 days. After your online consultation with a UK-licensed prescriber, if approved, your prescription is sent to a GPhC-registered pharmacy. Your first Mounjaro KwikPen is usually dispatched within 24–48 hours. NHS routes take significantly longer due to specialist referral pathways and waiting lists.
What happens during a private online consultation for Mounjaro?
A UK-licensed prescriber reviews your medical history, current medications, fibromyalgia status, weight, height, and BMI. They check for contraindications and discuss realistic expectations, side effects, and monitoring requirements. The consultation typically lasts 20–30 minutes. You'll need to provide honest information about your health to ensure the medication is safe for you.
Does Mounjaro cost more as I increase my dose during titration?
Yes. Mounjaro starts at 2.5 mg (approximately £129–£150 per month) and increases by 2.5 mg every 4 weeks. At 15 mg (maximum dose), costs reach approximately £280–£320 per month. Some private providers offer fixed pricing across all doses, so ask about their pricing structure before committing.
Can fibromyalgia side effects interact with Mounjaro side effects?
Mounjaro commonly causes nausea, constipation, or diarrhoea—these may feel similar to fibromyalgia symptoms or fatigue patterns. It's essential to report any changes to your prescriber. They can adjust your dose, offer anti-nausea support, or switch you to an alternative medication like Wegovy if side effects are unmanageable. Regular communication is key.
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.