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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Monjaro 5mg — NHS Weight Loss Guidance for UK Adults
Monjaro 5mg is the first maintenance dose of tirzepatide, a prescription-only dual GIP and GLP-1 receptor agonist injection licensed in the UK for weight management. In NHS and private settings, patients typically reach the 5mg dose after four weeks on the starting 2.5mg dose. Understanding how this dose fits into NHS tier 3 specialist weight management services, eligibility criteria, and what clinical evidence shows can help you and your GP make informed decisions about weight loss treatment. Our free BMI calculator can help you check your current health status before exploring treatment options.
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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.
NHS Eligibility and Tier 3 Services for Monjaro
NHS access to Monjaro is available through specialist tier 3 weight management services, not standard GP prescriptions. You must be referred to your local NHS specialist weight management service by your GP. Eligibility criteria are: BMI of 30 kg/m² or above, or BMI of 27–29.9 kg/m² with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, or cardiovascular disease.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS applies lower BMI thresholds (starting from 27.5 kg/m²) because these groups face higher metabolic health risks at lower weights. Once referred, you'll undergo clinical assessment at the specialist service. If Monjaro is appropriate, you'll typically start at 2.5mg weekly for four weeks, then escalate to 5mg. The tier 3 service will manage your care, monitor side effects, and adjust doses based on your response.
- Referral required from your GP to specialist tier 3 service
- Clinical assessment needed before prescription
- Escalation from 2.5mg to 5mg over four weeks
- Ongoing specialist monitoring and support included
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 Routes for Accessing Monjaro 5mg in the UK
In the UK, there are two routes to access Monjaro. The NHS route involves GP referral to a tier 3 specialist weight management service, which is free but often has long waiting lists (ranging from weeks to many months depending on your region and local capacity). The private route allows you to access Monjaro through a GPhC-registered online pharmacy following a consultation with a UK-licensed prescriber, without NHS waiting lists, though you pay privately (typically £150–£200+ per month depending on dose).
Both routes require proper clinical assessment and a valid prescription. The NHS route includes specialist medical support and monitoring as part of the service. The private route means you have direct access to licensed prescribers and pharmacies but manage your own record-keeping and contact your prescriber if you have concerns. Our GLP-1 weight loss calculator can help you estimate potential outcomes at the 5mg dose based on clinical trial data.
- 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.
How long does it take to reach Monjaro 5mg on the NHS?
You start at 2.5mg for four weeks, then escalate to 5mg. So you'll typically reach the 5mg dose around week 5 of treatment. Your specialist team will monitor your response and side effects throughout this period before any further dose changes.
Is Monjaro 5mg the maximum dose I can take?
No, 5mg is the first maintenance dose, not the maximum. Depending on your response and tolerability, your specialist may increase you further to 7.5mg, 10mg, 12.5mg, or the maximum of 15mg. Dose adjustments happen at minimum four-week intervals.
What weight loss should I expect at 5mg based on clinical evidence?
Clinical trials (SURMOUNT-1) showed average weight loss of around 15% of body weight at the 5mg dose after 72 weeks, alongside a reduced-calorie diet and physical activity. Individual results vary significantly — some lose more, some less. Use our weight loss calculator to see estimates based on your starting weight.
Can my GP prescribe Monjaro 5mg directly, or do I need a specialist referral?
Monjaro is currently only prescribed through NHS tier 3 specialist weight management services, not through standard GP prescribing. Your GP will refer you to your local service if you meet eligibility criteria. Private prescribing is available outside the NHS through online services.
What are the most common side effects at the 5mg dose?
Nausea, diarrhoea, constipation, and stomach pain are the most common side effects. These typically reduce over time as your body adjusts. Injection site reactions (redness or bruising) are also common. Serious side effects are rare but seek urgent care for severe stomach pain or allergic reactions.
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.