The UK's most complete GLP-1 guide
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- 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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Staying on 2.5mg Mounjaro in the UK
Many people wonder whether they should remain on the 2.5mg starting dose of Mounjaro or progress to a higher strength. In the UK, 2.5mg is the standard initial dose, and your prescriber will assess whether dose escalation is right for you based on your individual health, weight loss progress, and how well you tolerate the medication. This guide explains what staying on 2.5mg means and when stepping up your dose might be considered within NHS guidelines and private prescribing services.
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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.
NHS Mounjaro Dosing and Escalation Guidelines
Mounjaro dosing follows a structured escalation protocol in the UK. The 2.5mg dose is given once weekly for the first 4 weeks as the starting/adjustment phase. After 4 weeks, your prescriber typically reviews your progress and may recommend stepping up to 5mg for weeks 5–8, then 7.5mg, 10mg, 12.5mg, and finally 15mg as the maximum licensed dose.
However, staying on 2.5mg is an option if:
- You are experiencing significant side effects at higher doses
- You are achieving meaningful weight loss and your prescriber is satisfied with progress
- You have medical conditions that make escalation inadvisable
- You prefer a lower maintenance dose due to tolerability
In clinical trials, participants taking tirzepatide (the active ingredient in Mounjaro) typically escalated through doses, but individual treatment plans vary. Your GP or prescriber will decide the best approach for you. Unlike Wegovy, which has a fixed maximum dose of 2.4mg, Mounjaro offers more flexibility in dose selection, and remaining on a lower therapeutic dose is clinically acceptable if it meets your health goals.
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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.
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NHS vs Private: Accessing Mounjaro in the UK
NHS access to Mounjaro is through specialist tier 3 weight management services following a GP referral. NICE (National Institute for Health and Care Excellence) has approved tirzepatide for use within these services, but availability varies significantly by region and local Integrated Care Board (ICB) decisions. NHS waiting lists can extend several months to over a year in many areas.
Private prescribing offers faster access without NHS referral. A UK-licensed prescriber conducts an online clinical assessment and, if appropriate, issues a prescription dispensed by a GPhC-registered pharmacy. Whether you use our GLP-1 weight loss calculator to estimate potential outcomes or discuss Mounjaro vs Wegovy options with your private prescriber, the decision to stay on 2.5mg remains yours in consultation with your healthcare provider.
- 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 stay on 2.5mg Mounjaro long-term?
Yes, if your prescriber agrees it is appropriate for your health goals and you are tolerating it well. However, 2.5mg is designed as a starting dose. Most people escalate after 4 weeks, but individual circumstances vary. Discuss your specific situation with your prescriber.
What happens if I don't want to escalate from 2.5mg?
Inform your prescriber. If you are achieving good weight loss results and managing side effects well, staying on 2.5mg may be acceptable. Your prescriber will assess whether this dose continues to meet your treatment goals.
Is 2.5mg Mounjaro enough for weight loss?
Clinical trials showed that higher doses (15mg) produced greater average weight loss, but individual results vary widely. Some people see meaningful results at lower doses, while others require escalation. Your prescriber will monitor your progress.
How does Mounjaro 2.5mg compare to Wegovy?
Mounjaro uses a dual GIP and GLP-1 mechanism, while Wegovy is a GLP-1-only injection. Comparing the two directly is complex and depends on individual response. Your prescriber can discuss which is more suitable for you.
What if I experience side effects on 2.5mg Mounjaro?
Side effects often improve with time. However, tell your prescriber immediately if you have severe nausea, vomiting, stomach pain, or other concerns. They may recommend staying on 2.5mg longer before escalating, or adjusting your approach entirely.
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.