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 Store Mounjaro — Temperature Guide & UK Access
Mounjaro (tirzepatide) requires proper storage to remain effective. If you're prescribed this once-weekly injection, understanding the correct storage temperature is essential for safety and efficacy. This guide explains exactly how to store your Mounjaro KwikPen, the costs involved in accessing it across the UK, and whether you can get it through the NHS or need to go private. Use our GLP-1 weight loss calculator to explore potential outcomes, and our BMI calculator to check your eligibility for treatment.
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.
Mounjaro Storage Temperature & Shelf Life
Unopened Mounjaro pens must be stored in a refrigerator between 2°C and 8°C (standard fridge temperature). Keep the KwikPen in its original carton to protect it from light, and do not freeze—if your pen freezes, do not use it. Unopened pens can be stored safely until the expiry date printed on the carton.
After you start using your first pen, it can be kept at room temperature (below 30°C) for up to 30 days. Once 30 days have passed since first use, you must dispose of the pen safely, even if it still contains medication. Store away from direct heat and sunlight. Never store Mounjaro in the freezer compartment or leave it in a car on a warm day. These storage rules apply regardless of whether you access tirzepatide through NHS specialist services or private prescription.
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 & UK Access Routes
Mounjaro access in the UK splits into two routes: NHS specialist services and private prescription. Through the NHS, tirzepatide is available via tier 3 weight management services after GP referral, though waiting times vary significantly by region and can be several months. Private prescription costs typically range from £150–£300 per month depending on the dose. Starting doses (2.5 mg) cost less than maximum doses (15 mg). Private access requires an online consultation with a UK-registered prescriber who assesses eligibility, then a GPhC-registered pharmacy dispenses your prescription. Both routes require a clinical assessment—this is not available over the counter.
- 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 temperature should I store Mounjaro at?
Store unopened Mounjaro KwikPens in a refrigerator between 2°C and 8°C in the original carton. After first use, keep at room temperature (below 30°C) for up to 30 days. Never freeze.
Can I use Mounjaro if it's been frozen?
No. If your Mounjaro pen has been frozen, do not use it. Freezing damages the medication. Dispose of it safely and contact your prescriber or pharmacy for a replacement.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £150–£300 per month depending on your dose. Starting doses (2.5 mg) are less expensive than maximum doses (15 mg). Prices vary by provider.
Can I get Mounjaro free on the NHS?
Yes, through NHS tier 3 specialist weight management services following a GP referral. However, availability and waiting times vary significantly across UK regions. Your GP can advise on local services.
How long can I keep Mounjaro after opening it?
Once you start using a Mounjaro KwikPen, it can be kept at room temperature (below 30°C) for up to 30 days. After 30 days, dispose of it safely even if medication remains.
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.