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
Where to Store Mounjaro: UK Storage and Handling Guide
Proper storage of your Mounjaro KwikPen is essential to maintain its effectiveness and safety. In the UK, Mounjaro (tirzepatide) must be stored at specific temperatures depending on whether the pen has been opened. This guide explains exactly how to store your prescription injection safely, following MHRA and manufacturer guidance, so you can get the most from your weight management treatment.
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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.
Storage Before and After First Use
Unopened Mounjaro pens must be stored in a refrigerator at 2°C to 8°C until you're ready to use them. Keep the pens in their original carton to protect them from light, and do not freeze them — if a pen freezes, it cannot be used and must be disposed of. Unopened pens can remain in the refrigerator until their expiry date printed on the carton.
After you first use a pen, you can store it at room temperature below 30°C for up to 30 days. Keep it away from heat and direct sunlight during this period. After 30 days from first use, the pen must be disposed of safely, even if there is still medication remaining inside.
- Store unopened pens in the fridge (2–8°C) in original carton
- Never freeze — frozen pens cannot be used
- After first use, room temperature storage (below 30°C) is acceptable for up to 30 days
- Dispose of pens after 30 days of 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.
Safe Disposal and Travel Considerations
When disposing of your used Mounjaro KwikPen, do not put it in household waste or flush it down the toilet. Instead, place the pen in a sharps bin (a hard plastic yellow container designed for needles and injections). Your pharmacy will provide a sharps bin when you collect your first prescription, or you can request one if needed. If you're travelling within the UK or abroad, keep your pens in a cool bag with ice packs during transport, but ensure they don't directly touch ice. Always carry your prescription documentation with you — this is especially important when travelling internationally, as Mounjaro regulations vary by country.
- 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.
Can I store Mounjaro in a regular freezer?
No. Freezing Mounjaro damages the medication and makes it unusable. Keep unopened pens in a fridge at 2–8°C only. If a pen accidentally freezes, do not use it — dispose of it in your sharps bin and contact your prescriber or pharmacy.
How do I know if my Mounjaro has been stored correctly?
Check the pen before each injection. The liquid should be clear and colourless. Do not use the pen if the liquid is cloudy, discoloured, or contains particles. If you're unsure, contact your pharmacy or GP.
What should I do if I'm away from home and can't refrigerate my Mounjaro?
You can store an opened pen at room temperature (below 30°C) for up to 30 days. If you're travelling for longer periods, use a portable cool bag with ice packs to maintain the correct temperature, or arrange for a prescription to be issued at your destination.
Can I reuse a Mounjaro pen after 30 days?
No. All Mounjaro pens must be disposed of 30 days after first use, regardless of how much medication remains. Your pharmacy will provide a sharps bin for safe disposal.
Is Mounjaro storage different if I'm receiving it through the NHS?
No. Whether you receive Mounjaro through an NHS specialist weight management service or via private prescription, storage requirements are identical — refrigerate unopened pens, dispose after 30 days of opening, and always use a sharps bin for needle disposal.
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.