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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How to Access Mounjaro for Weight Loss in the UK
Mounjaro (tirzepatide) is a prescription-only weekly weight loss injection available in the UK through both NHS specialist services and private online prescribing. Access and costs vary significantly depending on your route — NHS availability is limited and requires referral to tier 3 weight management services, whilst private prescription is more immediately accessible but involves out-of-pocket costs. This guide explains both pathways, what you'll need to qualify, and what to expect from the assessment process.
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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.
Private Mounjaro Access and Costs in the UK
Private prescription of Mounjaro in the UK is available through GPhC-registered online pharmacies following a clinical assessment by a UK-licensed prescriber. Typical costs range from £129 to £320 per month depending on your dose — higher doses naturally cost more, and prices vary between providers.
- Starting dose (2.5 mg): approximately £129–£150 per month
- Mid-range doses (5–10 mg): approximately £180–£240 per month
- Maximum dose (15 mg): approximately £280–£320 per month
Each KwikPen contains four weeks' supply. The online assessment typically takes 15–20 minutes and asks about your medical history, current medications, weight-related health conditions, and lifestyle. If approved, your prescription is issued electronically and dispensed by a registered UK pharmacy within 1–3 working days. You'll need to store pens in a fridge at 2–8°C before use.
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: What's the Difference?
NHS route: Free prescription through tier 3 specialist weight management services following GP referral. However, NHS availability is extremely limited — many regions have waiting lists of 6 months to 2+ years, and not all ICBs fund tirzepatide yet. Your GP must refer you, and assessment happens through a specialist multidisciplinary team.
Private route: Faster access — often within days — but you pay upfront. No GP referral needed. A prescriber assesses you via online consultation. Both routes require a clinical assessment confirming you meet eligibility criteria: BMI 30+ or BMI 27–29.9 with weight-related health conditions like type 2 diabetes, hypertension, or sleep apnoea. Use our free BMI calculator above to check where you stand before starting any assessment.
The private online consultation process is straightforward. You'll complete a health questionnaire covering your weight history, medical conditions, medications, allergies, and lifestyle. A licensed prescriber (usually a doctor or pharmacist prescriber) reviews your answers within 24 hours. If Mounjaro is deemed suitable, a prescription is issued. If not, the prescriber explains why — common reasons for decline include untreated thyroid conditions, personal or family history of medullary thyroid cancer, or use of certain diabetes medications. Once prescribed, your dose will start at 2.5 mg and increase gradually — most prescribers require at least 4 weeks between dose increases, following clinical guidance. Track your progress using our free progress tracker throughout your Mounjaro journey.
- 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.
Does the NHS prescribe Mounjaro for weight loss?
Yes, Mounjaro (tirzepatide) is NICE-approved for NHS use in specialist weight management services (tier 3). However, availability is severely limited — many NHS regions have waiting lists exceeding 12 months, and not all ICBs fund it. You'll need a GP referral and assessment through a specialist team. Private prescription is often faster.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £129–£320 per month depending on your dose and provider. Starting dose (2.5 mg) is around £129–£150; maintenance doses (5–15 mg) range £180–£320. Prices vary between online pharmacies, so it's worth comparing. Each KwikPen provides four weeks of treatment.
What happens during a private Mounjaro consultation?
You complete an online health questionnaire covering your weight, medical history, medications, and lifestyle. A UK-licensed prescriber reviews this within 24 hours and assesses whether Mounjaro is suitable for you. If approved, you receive an electronic prescription sent to a GPhC-registered pharmacy for dispensing within 1–3 working days.
Can I get Mounjaro privately without NHS referral?
Yes. Private prescription of Mounjaro doesn't require GP involvement — you can access it directly through online prescribing services. You'll still need a clinical assessment showing you meet eligibility criteria (BMI 30+ or BMI 27.5+ with weight-related health conditions for some ethnic groups), but you don't need NHS referral or a GP letter.
How is Mounjaro dosed when you first start?
Mounjaro follows a dose titration schedule. You start at 2.5 mg once weekly, then increase to 5 mg after 4 weeks, then potentially to 7.5 mg, 10 mg, 12.5 mg, and up to 15 mg. Each dose increase requires at least 4 weeks at the previous dose. Your prescriber monitors your response and may adjust the schedule based on side effects or weight loss progress. Clinical trials showed that at 15 mg weekly, participants lost an average of approximately 20.9% of body weight alongside diet and exercise.
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.