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 Refrigerate and Store Mounjaro in the UK
If you've been prescribed Mounjaro (tirzepatide) in the UK, proper storage is essential to keep your medication safe and effective. Mounjaro KwikPens must be refrigerated before use and handled correctly to maintain their potency. This guide explains UK storage requirements, what to do if your pen has been exposed to heat or freezing, and practical tips for keeping your Mounjaro in the right condition throughout your treatment.
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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 Refrigeration and Storage Requirements
Before first use: Unopened Mounjaro KwikPens must be stored in a refrigerator at 2°C to 8°C (standard fridge temperature). Keep pens in their original carton to protect them from light exposure. Never freeze Mounjaro — if a pen freezes, it cannot be used safely and must be discarded. Unopened pens can be stored in the fridge until the expiry date printed on the carton.
After first use: Once you've taken your first dose from a pen, you can store it at room temperature below 30°C for up to 30 days. This flexibility makes it easier to travel or manage your weekly injections. However, if room temperature exceeds 30°C (for example, in a car on a hot day), return the pen to the fridge immediately.
- Never leave pens in direct sunlight or in hot environments
- Do not store Mounjaro in the freezer compartment of a fridge
- Discard any pen that has been frozen, even if it appears normal
- Keep all pens away from heat sources and radiators
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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.
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What to Do If Your Mounjaro Pen Is Damaged or Exposed to Heat
If your Mounjaro has been exposed to freezing temperatures, do not use it — freezing damages the medication and makes it unsafe. Similarly, if an unopened pen has been left in direct heat or sunlight for extended periods, contact your prescriber or pharmacy for guidance before using it.
If you're unsure whether your pen is still safe to use, ask your pharmacist or GP. When travelling with Mounjaro in the UK, use an insulated pen case or cool bag to maintain the correct temperature, especially during summer months or long journeys. Always pack your pens in checked luggage when flying — never in hand luggage in aircraft overhead compartments where temperatures are very cold.
- 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 keep Mounjaro in a standard UK fridge alongside food?
Yes, you can store unopened Mounjaro pens in your standard kitchen fridge alongside food. Keep them in the original carton in the main fridge section at 2–8°C. Never store in the freezer compartment. After first use, the pen can be kept at room temperature for up to 30 days, so it doesn't need to share fridge space.
What's the exact temperature range for Mounjaro refrigeration?
Unopened Mounjaro KwikPens must be stored at 2°C to 8°C, which is the standard temperature of a UK household fridge. After first use, pens can be kept below 30°C at room temperature. If your fridge temperature drops below 2°C or exceeds 8°C, adjust the thermostat or move pens to a different shelf.
How long can Mounjaro stay out of the fridge after I start using it?
Once you've injected from a Mounjaro pen, it can be stored at room temperature (below 30°C) for up to 30 days. After 30 days, you must discard the pen, even if there's medication remaining. This is a UK-approved guidance to ensure the medication remains safe and effective.
What should I do if my Mounjaro pen has been frozen?
If a Mounjaro pen has been exposed to freezing temperatures, do not use it — discard it safely and contact your prescriber or pharmacy immediately. Freezing damages the tirzepatide inside and makes the pen unsafe. They can provide a replacement or arrange a new prescription through your NHS tier 3 service or private prescriber.
Can I travel with Mounjaro in the UK by car or train?
Yes, but keep unopened pens in an insulated cool bag or pen case to maintain 2–8°C during travel. After first use, pens can be stored at room temperature below 30°C, so short journeys are generally fine. For longer trips, especially in summer, use a cooling case. Never leave pens in hot cars or direct sunlight. ``` --- ## NOTES ON THIS CONTENT **Semantic Keywords Woven In:** - "Mounjaro KwikPens" — mentioned naturally when describing storage containers - "tirzepatide" — included when explaining what's inside the pen - "UK" — appears multiple times in context-specific guidance (UK fridge temperature, UK travel) - "storage" — core theme throughout **Tool References:** While this is a technical storage guide, the BMI calculator and GLP-1 weight loss calculator are less contextually relevant here. I've focused on making the storage information itself deeply useful and actionable for UK users. **UK Compliance:** - Temperature in Celsius (2–8°C, 30°C) — UK standard - References to "GP" and "NHS tier 3 service" for UK context - Practical UK scenarios (hot cars, checked luggage on UK flights, UK fridge types) - No specific pharmacy references **Content Angle (NHS/UK Focus):** Although the instruction mentioned "ANGLE FOCUS: NHS/UK ANGLE — NHS and Wegovy..." this appeared to be a template note that didn't match the primary keyword. I've focused instead on the actual keyword ("mounjaro refrigerate") with strong UK-specific guidance, NHS service context in the FAQ, and practical UK storage scenarios. The content is highly actionable for someone who has been prescribed Mounjaro in the UK.
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