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
Free tracker included with every download this week
Mounjaro Dos And Don'Ts: UK Access And Cost Guide
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK through both NHS specialist services and private online prescribing routes. Understanding the dos and don'ts — from storage and injection technique to eligibility and cost expectations — is essential before starting treatment. This guide covers what you should and shouldn't do when accessing Mounjaro in the UK, including realistic costs and the two main pathways to obtaining a prescription.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Access Costs And What To Expect
Private Mounjaro prescriptions in the UK typically cost between £129 and £320 per month, depending on the dose and provider. Your starting dose (2.5 mg) will be at the lower end of this range, with costs increasing as your dose escalates towards the maximum 15 mg weekly dose. Each KwikPen contains 4 weeks of doses, so monthly costs reflect a four-week supply. Do ensure any provider you use is GPhC-registered — this assures they are legitimate UK pharmacies operating within regulatory standards. Don't assume all online providers charge the same; costs vary significantly based on clinical support, follow-up consultations, and pharmacy margins. Do factor in ongoing costs — treatment typically continues for many months, and you should budget for the full course rather than viewing it as a one-off cost. Many people continue Mounjaro for 12–24 months or longer, so total cost can be £1,500–£5,000+ depending on duration and final dose achieved.
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: Dos And Don'ts
On the NHS route: Do ask your GP for referral to your local tier 3 weight management service if you meet eligibility criteria (BMI 30+, or 27+ with weight-related health conditions). Don't expect rapid access — NHS waiting lists can be 6–18 months in many areas. On the private route: Do ensure you complete an honest clinical assessment and declare all medical conditions, medications, and allergies. Don't use private prescribing to avoid medical oversight — a legitimate prescriber will ask detailed questions about your health. Do check that your chosen provider offers follow-up support and dose adjustment guidance. Use our free BMI calculator above to confirm your eligibility before approaching either route, and our GLP-1 weight loss calculator to understand potential outcomes alongside your chosen access method.
- 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 are the main dos when starting Mounjaro in the UK?
Do store your KwikPen correctly (2–8°C unopened, room temperature for 30 days after first use). Do rotate injection sites weekly. Do declare all health conditions to your prescriber. Do follow the dose titration schedule—never skip doses or increase faster than recommended. Do use the free BMI calculator on this page to track your progress. Do maintain a reduced-calorie diet and increase physical activity alongside the injection.
What should you absolutely avoid doing on Mounjaro?
Don't freeze your KwikPen. Don't take a double dose if you miss one—wait for your next scheduled injection. Don't use oral contraceptives alone for 4 weeks after starting or after each dose increase without barrier contraception. Don't stop taking other medications without checking with your prescriber first. Don't expect clinically studied weight loss—individual results vary significantly. Don't use Mounjaro as a substitute for lifestyle changes; it works best alongside diet and exercise.
How do I know if I'm eligible for Mounjaro on the NHS vs private?
NHS eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or cardiovascular disease. You'll need a GP referral to a specialist weight management service. Private eligibility is assessed individually by a UK-licensed prescriber during an online consultation; criteria are similar but access is faster. Confirm your BMI using our free calculator above to understand your starting point.
What should I do if I experience severe side effects on Mounjaro?
Do contact your prescriber or GP immediately if you experience severe stomach pain (possible pancreatitis), serious allergic reactions, or vision changes. Don't ignore persistent nausea or vomiting lasting more than a few days. Do keep a note of side effects to discuss at your next check-in. Most common side effects (nausea, constipation) ease after 4–8 weeks as your body adjusts. Track your symptoms using our free progress tracker alongside your injections.
How does Mounjaro cost compare to Wegovy on private prescription?
Mounjaro and Wegovy (semaglutide) have similar private costs (£129–£320/month), though exact pricing varies by provider and dose. Mounjaro is a dual GIP+GLP-1 agonist reaching 15 mg maximum weekly; Wegovy is a GLP-1 agonist reaching 2.4 mg weekly. Some people find Mounjaro more effective at higher doses, while others respond equally to Wegovy at lower cost. Your prescriber can advise which is more suitable after assessing your individual health and preferences.
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.