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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Should You Go Up a Dose on Mounjaro in the UK?
Deciding whether to increase your Mounjaro dose depends on your individual response, side effects, and clinical guidance from your prescriber. Mounjaro is a prescription-only tirzepatide injection available in the UK through NHS specialist services or private online prescribing. Your prescriber will assess your progress, tolerability, and health goals to determine if dose escalation is appropriate. This guide explains how Mounjaro dosing works, what affects the decision to increase, and the cost and access options available to UK patients.
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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 Dose Escalation: How It Works in the UK
Mounjaro dose increases follow a structured escalation protocol. Treatment typically begins at 2.5 mg once weekly for the first 4 weeks, then steps up every 4 weeks (5 mg, 7.5 mg, 10 mg, 12.5 mg) until reaching the maximum 15 mg dose. However, not everyone needs to reach the maximum dose — many patients achieve their weight loss goals at lower doses like 5 mg or 10 mg. Your prescriber will assess whether to continue escalating based on three key factors:
- Weight loss progress: If you're losing weight steadily at your current dose, escalation may not be necessary.
- Side effects: If nausea, diarrhoea, or other side effects are significant, your prescriber may pause escalation or reduce the dose before retrying.
- Individual health factors: Gallbladder issues, pancreatitis history, gastroparesis, or medication interactions may influence dosing decisions.
The dose titration process is designed to find your optimal dose — the lowest effective dose with manageable side effects. Clinical trials showed that average weight loss improves with higher doses, but individual variation is substantial. Your GP or prescriber will guide the decision; never increase your dose independently.
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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.
Mounjaro Cost and Access in the UK: NHS vs Private
NHS access is available through tier 3 specialist weight management services, but availability varies significantly by region and waiting lists can be lengthy. Private access through a GPhC-registered pharmacy typically costs between £129 and £320 per month depending on your dose, with higher doses costing more. An online consultation with a UK-licensed prescriber assesses your eligibility, medical history, and BMI before prescription. NHS access is free once prescribed through specialist services, but requires GP referral and regional ICB approval. For both routes, your prescriber will monitor your progress and manage dose changes — this is not something you adjust yourself. Calculate your personal BMI using our free BMI calculator to understand where you stand on NHS eligibility thresholds (BMI ≥30, or ≥27 with weight-related health conditions). If you're already taking Mounjaro privately and wish to explore NHS options, discuss this with your current prescriber or GP.
- 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.
When should I ask my prescriber about increasing my Mounjaro dose?
Ask at your scheduled review appointment, typically after 4 weeks on your current dose. Bring notes about your weight loss, side effects, energy levels, and how you're feeling with hunger and appetite. If you're experiencing significant nausea or other side effects, mention this before requesting escalation — your prescriber may pause escalation to let side effects settle.
What if I'm on Mounjaro but want to switch to Wegovy instead?
Wegovy (semaglutide) is a different GLP-1 medication with a different dosing schedule. Any switch must be managed by your prescriber — they will consider your current dose, response, and tolerability. Approximate equivalence exists (Mounjaro 10 mg is roughly equivalent to Wegovy 1.7 mg), but no official conversion chart exists, so your prescriber will guide the transition carefully.
Does NHS NICE guidance specify which Mounjaro dose patients should reach?
NICE approval for tirzepatide focuses on eligibility and safety rather than prescribing a specific maximum dose. Your prescriber determines the appropriate dose based on your individual response, tolerability, and clinical assessment. Some patients benefit most at 5 mg or 10 mg; others require higher doses for optimal weight loss.
Can I access Mounjaro through the NHS if I've previously used it privately?
Yes, though processes vary by region. If you've been on private Mounjaro and wish to transfer to NHS specialist services, contact your GP to request a referral to your local weight management service. NHS prescribers will conduct their own assessment and may restart dosing from a lower dose, depending on your history.
What's the difference between Mounjaro and tirzepatide, and does this affect dosing?
Mounjaro is the brand name; tirzepatide is the active ingredient. They're the same medication — tirzepatide is what appears in prescriptions and clinical discussions. Dosing is identical regardless of whether it's referred to as Mounjaro or tirzepatide. Your prescriber will use both terms interchangeably.
Ready to take control of your weight loss journey?
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