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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Tirzepatide Doses on the NHS — Complete UK Guide
Tirzepatide, available as Mounjaro in the UK, is a prescription-only weekly weight loss injection. Access through the NHS requires referral to specialist tier 3 weight management services. This guide explains tirzepatide dosing schedules, NHS eligibility criteria, and how the dose escalation process works under NICE guidance. MyWeightCheck's free GLP-1 weight loss calculator helps you understand expected outcomes at different doses alongside NHS information.
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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 Tirzepatide Access and Dosing Schedule
NICE has approved tirzepatide for NHS use in specialist weight management services for eligible adults. Access is through tier 3 multidisciplinary weight management services, typically via referral from your GP.
Standard NHS dosing schedule:
- Weeks 1–4: 2.5 mg once weekly (starting/adjustment dose)
- Weeks 5–8: 5 mg once weekly (first maintenance)
- Weeks 9–12: 7.5 mg once weekly (if escalation needed)
- Weeks 13–16: 10 mg once weekly (if tolerated)
- Weeks 17–20: 12.5 mg once weekly (if appropriate)
- Week 21+: 15 mg once weekly (maximum dose)
NHS prescribers follow NICE guidance for dose escalation. The minimum interval between dose increases is 4 weeks. Your specialist will assess tolerability at each stage before increasing.
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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.
NHS Access vs Private Tirzepatide in the UK
NHS route: Referral to tier 3 specialist weight management services (normally from your GP). Assessment, prescription, and ongoing monitoring provided by the NHS. Waiting times vary significantly by region — some areas have waiting lists of several months or longer due to high demand.
Private route: Online consultation with a UK-licensed prescriber through registered pharmacies. Available without NHS referral. Costs typically £129–£320 per month depending on dose. Faster access than NHS in most areas. Both routes require clinical assessment and a valid prescription. Your GP can advise which route suits your 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.
What is the starting dose of tirzepatide on the NHS?
The NHS starting dose is 2.5 mg once weekly for the first 4 weeks. This is an adjustment dose to assess tolerability. Doses are then escalated to 5 mg and higher over subsequent weeks, with minimum 4-week intervals between increases, based on individual response and specialist guidance.
How quickly does tirzepatide dose increase on the NHS?
Tirzepatide is escalated slowly under NHS guidance. Each dose is maintained for at least 4 weeks before increasing to the next level. This careful approach allows your specialist to monitor side effects and effectiveness. Maximum escalation pace is one dose increase every 4 weeks.
Can I choose my tirzepatide dose, or is it set by the NHS?
Your NHS specialist prescriber determines the appropriate dose based on your clinical assessment, health conditions, tolerability, and response to treatment. Dose escalation is individualised — not everyone reaches the maximum 15 mg dose. Your preferences and any side effects are considered throughout.
What is the maximum tirzepatide dose available on the NHS?
The maximum licensed dose of tirzepatide (Mounjaro) is 15 mg once weekly. However, not all patients require this dose. Your specialist will prescribe the lowest effective dose for your individual needs. Some patients achieve good results at 5 mg or 10 mg.
How do tirzepatide and GLP-1 receptor agonist medications differ?
Tirzepatide is a dual GIP and GLP-1 receptor agonist — it activates two hormone pathways, whereas traditional GLP-1 medications like Wegovy activate one pathway only. This dual mechanism may contribute to tirzepatide's weight loss effects in clinical trials, though individual results vary significantly.
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.