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 Multiple Sclerosis — What UK Patients Should Know
If you have multiple sclerosis (MS) and are considering weight management medication, it's important to understand how Mounjaro works and whether it's suitable for you. Mounjaro (tirzepatide) is a prescription-only weight management injection licensed in the UK, but people with MS require specific medical considerations before starting any new medication. MS can affect metabolism, mobility, and medication interactions, so personalised medical advice from your GP or MS specialist is essential before proceeding with any weight loss 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.
Mounjaro Mechanism and MS Considerations
Mounjaro is a dual GIP and GLP-1 receptor agonist — it activates two natural hormone pathways to help regulate appetite, reduce food cravings, and support feeling fuller after smaller meals. Unlike single-mechanism GLP-1 injections like Wegovy (semaglutide), Mounjaro's dual action may provide different effects for some patients.
For people with MS, several factors require careful consideration:
- Medication interactions: MS treatments (including immunosuppressants and disease-modifying therapies) may interact with Mounjaro — your prescriber must review all current medications
- Gastroparesis risk: Mounjaro slows stomach emptying; MS can affect swallowing and digestion, increasing this risk
- Fatigue and mobility: MS-related fatigue may be affected by appetite changes — clinical assessment is essential
- Individual MS variation: MS affects each person differently; one person's experience is not predictive of another's
A UK-licensed prescriber and your MS specialist team must work together to assess suitability.
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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.
Assessment and Next Steps for MS Patients
If you have MS and are interested in exploring weight management options, speak with your MS specialist or GP first — do not start Mounjaro or any new medication without professional medical assessment. Your prescriber will need to review your specific MS diagnosis, current disease-modifying therapies, other medications, and overall health status.
Weight management itself can benefit people with MS by reducing stress on joints and improving mobility in some cases. However, this must be achieved safely and in coordination with your MS care team. Use our free BMI calculator to understand your current weight status, and then discuss the results and options with your healthcare team. Some people may be better suited to Wegovy, Saxenda, or non-pharmacological weight management approaches depending on individual circumstances.
- 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 take Mounjaro if I have multiple sclerosis?
Mounjaro requires individual clinical assessment. People with MS can potentially use weight management medication, but your MS specialist and prescriber must assess your specific situation, current treatments, and any MS-related complications. MS affects digestion and medication metabolism differently in each person, so professional medical advice is essential before starting any new injection.
Will Mounjaro interact with my MS medications?
Mounjaro may interact with disease-modifying MS therapies and immunosuppressants. Your prescriber must review all current MS treatments before issuing a Mounjaro prescription. Never start Mounjaro without informing your healthcare team of all medications — this is a critical safety step. Your GP and MS specialist should communicate directly about suitability.
Does MS affect how Mounjaro works?
MS can affect digestion, stomach emptying, and medication absorption — all relevant to how Mounjaro functions. Additionally, Mounjaro slows gastric emptying, which may be problematic if MS affects your swallowing or digestion. Individual MS variation means effects are unpredictable. Clinical assessment by someone familiar with both MS and weight management is necessary.
Should I consider Wegovy instead of Mounjaro if I have MS?
Both Mounjaro and Wegovy require individual assessment for MS patients. Wegovy is a single GLP-1 agonist rather than dual-mechanism like Mounjaro, but both slow stomach emptying. Neither is automatically better for MS — your prescriber and MS team will determine which, if any, is appropriate based on your specific health profile and current treatments.
How do I start the assessment process for weight management with MS?
Begin by discussing weight management goals with your GP or MS specialist. They may refer you to a specialist weight management service (NHS tier 3) or recommend a private online consultation with a UK-licensed prescriber experienced in MS care. Always disclose your MS diagnosis, current treatments, and any complications during any assessment — this information is vital for safety.
Ready to take control of your weight loss journey?
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