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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Back Pain and Mounjaro — What You Need to Know
Back pain is often linked to excess weight, and losing weight through prescription injections like Mounjaro (tirzepatide) may help reduce pressure on joints and improve pain. If you're considering Mounjaro or wondering how it compares to Wegovy, it's important to understand how each works, potential side effects, and whether either is right for you. This guide explains the key differences and how back pain fits into the weight management picture. Use our free BMI calculator to check your current weight category and eligibility for treatment.
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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 Mounjaro and Wegovy Compare for Back Pain Relief
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only weight loss injections used in the UK. Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Wegovy is a GLP-1 agonist only — this means Mounjaro activates two appetite-regulation pathways rather than one.
- Mounjaro: Clinical trials (SURMOUNT-1) showed average weight loss of 15–21% body weight over 72 weeks alongside diet and exercise
- Wegovy: Clinical trials (STEP-1) showed average weight loss of approximately 15% body weight over 68 weeks alongside lifestyle changes
- Back pain context: Even a 5–clinically studied weight loss can reduce joint stress and improve mobility, potentially easing back pain — though individual results vary
Both require a clinical assessment from a UK-licensed prescriber and are prescribed based on individual health needs, not perceived superiority.
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.
Which Is More Suitable for You?
Your prescriber will decide which medication suits you based on your medical history, current medications, and individual needs — not on which is "better" overall. If back pain is a concern, mention this during your clinical assessment, as your prescriber needs to understand your full health picture.
- Both injections may cause nausea or stomach upset initially — important if you have existing digestive issues
- Both require weekly injections and dose titration over several weeks
- Both are most effective alongside reduced-calorie diet and increased physical activity
- Access in the UK is through NHS specialist tier 3 services or private online prescribing following clinical assessment
Try our free GLP-1 weight loss calculator to estimate potential weight loss outcomes with either medication.
- 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 Mounjaro or Wegovy help back pain directly?
These injections do not treat back pain directly. However, weight loss may reduce pressure on the spine and joints, potentially easing pain. Clinical evidence shows that even 5–clinically studied weight loss improves mobility and reduces joint strain. Always discuss back pain with your GP alongside any weight loss plan.
Which causes more back pain as a side effect?
Neither Mounjaro nor Wegovy lists back pain as a common side effect in UK clinical trials. Very common side effects are nausea, diarrhoea, and stomach pain. If you experience back pain during treatment, inform your prescriber — it may be unrelated to the medication.
How quickly will weight loss help my back pain?
Weight loss typically occurs gradually over weeks and months. Most people see noticeable changes after 8–12 weeks. Back pain improvement depends on the cause of your pain, severity, and individual factors — discuss realistic timelines with your GP.
Do I need a prescription to buy Mounjaro or Wegovy in the UK?
Yes, both are prescription-only medicines. You cannot buy them over the counter. You need a clinical assessment from a UK-licensed prescriber (through NHS specialist services or private online prescribing) before a prescription can be issued.
What if I have other health conditions alongside back pain?
Inform your prescriber about all health conditions, medications, and concerns during your clinical assessment. This ensures the medication is safe for you personally. Your prescriber may recommend additional support for back pain management alongside weight loss treatment.
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.