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
How to Keep Mounjaro in the Fridge — UK Storage & Access Guide
Mounjaro KwikPen pens must be stored in a refrigerator at 2–8°C before first use and should never be frozen. If you've been prescribed tirzepatide and need to understand storage requirements, costs, and how to access this medication in the UK, this guide covers everything you need to know about keeping your pens properly stored and where to get them.
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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.
Mounjaro Storage Rules and Refrigerator Requirements
Before first use (unopened pens): Store all Mounjaro KwikPen pens in a refrigerator between 2°C and 8°C. Keep them in the original carton to protect from light. Unopened pens can be used until the expiry date printed on the box. Never freeze Mounjaro — if a pen has been frozen, do not use it.
After first use: Once you've used a pen for the first time, you can store it at room temperature below 30°C for up to 30 days. After 30 days, dispose of the pen safely in a sharps bin. Keep all pens away from direct sunlight and heat sources.
Travel tips: If you're travelling, use an insulated bag with ice packs to keep unopened pens at the correct temperature. Once opened, a pen can safely travel at room temperature for short periods as long as it's used within 30 days of first 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.
Mounjaro Cost in the UK: NHS vs Private Access
Access to Mounjaro (tirzepatide) in the UK varies significantly depending on your route.
NHS access: NICE has approved tirzepatide for use within specialist weight management services. However, access is through tier 3 or 4 services — your GP cannot prescribe directly. You'll need a referral and assessment by a specialist team. Waiting times vary by region and can be several months in many areas.
Private access: Available through GPhC-registered online prescribing services following an online clinical assessment. Costs typically range from £129–£320+ per month depending on the dose and provider. Monthly costs increase at higher doses. This route offers faster access without NHS waiting lists.
- 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 cold does my fridge need to be for Mounjaro storage?
Mounjaro pens must be stored at 2–8°C (standard fridge temperature). Check your fridge thermometer to confirm. Most UK household fridges maintain this temperature. If your fridge is colder than 2°C, store pens in the warmest part. Never allow pens to freeze — this makes them unsafe to use.
Can I store Mounjaro outside the fridge once I've started using it?
Yes. After the first injection, your opened Mounjaro KwikPen can be stored at room temperature below 30°C for up to 30 days. After 30 days, discard it safely in a sharps bin. Keep it away from direct sunlight and heat. This flexibility makes it easier for travel and daily use.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £129–£320+ per month depending on your dose. The 2.5 mg starting dose is usually cheapest; the 15 mg maximum dose is most expensive. Prices vary between prescribing services. Always ask for a full quote including all doses if you plan to increase over time. Our GLP-1 weight loss calculator can help you estimate costs across doses.
How do I access Mounjaro through the NHS in the UK?
Ask your GP for a referral to your local tier 3 or 4 specialist weight management service. NICE guidance supports tirzepatide for eligible adults. You'll need a BMI of 30+ or 27+ with weight-related health conditions. Assessment by the specialist team determines if Mounjaro is appropriate. Waiting times and availability vary significantly by region — ask your GP about timescales in your area.
What's the difference between Mounjaro and Wegovy for UK cost?
Both are prescription-only GLP-1 or GLP-1/GIP medications available privately in the UK. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist; Wegovy (semaglutide) is GLP-1 only. Private costs are similar — roughly £129–£320 per month depending on dose. Both require clinical assessment before prescription. Compare options with your prescriber based on eligibility and suitability rather than cost alone.
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.