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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Can Mounjaro Make You Cold?
Feeling unusually cold is not listed as a common or very common side effect of Mounjaro (tirzepatide) in UK clinical data, though some patients do report temperature sensitivity changes. This informational guide explains what the evidence shows, what side effects are actually common with Mounjaro, and when you should contact your GP if you experience unexpected symptoms. If you're considering Mounjaro for weight management, understanding the full side effect profile — including rarer effects — helps you make an informed decision about prescription treatment alongside lifestyle changes.
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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.
Mounjaro Side Effects and Temperature Sensitivity
Mounjaro (tirzepatide) is a prescription-only weight management injection that works as a dual GIP and GLP-1 receptor agonist. The most common side effects reported in clinical trials and NHS prescribing data are gastrointestinal — nausea, diarrhoea, vomiting, and constipation affect more than 1 in 10 people during the initial weeks. Feeling cold or chills is not classified as a very common side effect by the MHRA, but some patients on GLP-1 medications (like semaglutide in Wegovy) and tirzepatide report subjective temperature changes.
- Very common GI effects: nausea, diarrhoea, vomiting, constipation, stomach pain
- Common effects: indigestion, headache, fatigue, dizziness, injection site reactions, hair loss
- Temperature sensitivity: reported anecdotally by some patients; not formally listed as common
- Dose titration may reduce early side effects as your body adjusts to each escalation
If you experience persistent feeling of cold, especially alongside other unusual symptoms, contact your GP or your prescriber. They can assess whether it's related to Mounjaro or another cause like thyroid function changes or nutritional deficiency.
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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.
How to Access Mounjaro in the UK and What It Costs
Mounjaro is available in the UK through two main routes: NHS specialist weight management services and private prescription via online assessments. NHS access requires referral to a tier 3 or 4 weight management service through your GP, but availability varies significantly by region and waiting lists can be months or years. Private prescription routes offer faster access following an online clinical assessment with a UK-licensed prescriber at GPhC-registered pharmacies, typically costing £129–£320 per month depending on your dose.
- NHS route: GP referral to specialist services (availability varies by region)
- Private route: online consultation with prescriber, then pharmacy dispensing
- Dosing: starts at 2.5mg, escalates to maximum 15mg over weeks, affecting total cost
- Always have a clinical assessment before starting — Mounjaro is prescription-only and requires eligibility review
- 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.
Is feeling cold a side effect of Mounjaro?
Feeling cold is not listed as a common side effect of Mounjaro in UK prescribing data. However, some patients on GLP-1 and GIP/GLP-1 medications report temperature sensitivity. If you experience persistent chills or feeling unusually cold, contact your GP to rule out other causes like thyroid changes or nutritional deficiency.
What are the most common Mounjaro side effects?
The very common side effects (affecting more than 1 in 10 people) are gastrointestinal: nausea, diarrhoea, vomiting, and constipation. These typically improve within the first few weeks. Fatigue, headache, and injection site reactions are also common. Side effects often reduce as your body adjusts during dose titration.
How much does Mounjaro cost on the NHS in the UK?
Mounjaro is available through NHS specialist weight management services free at the point of use, but access requires referral and varies significantly by region. Many areas have long waiting lists. Private prescriptions typically cost £129–£320 monthly depending on your dose and provider.
Can I get Mounjaro on prescription without waiting for NHS referral?
Yes. You can access Mounjaro through private online prescription services following a clinical assessment with a UK-licensed prescriber. A GPhC-registered pharmacy then dispenses it. This bypasses NHS waiting lists but involves a private cost. Always ensure the prescriber is registered with the General Pharmaceutical Council.
Should I stop Mounjaro if I feel unusually cold?
Do not stop Mounjaro without speaking to your prescriber first. If you experience unusual cold sensitivity or chills, contact your GP or the prescriber who issued your Mounjaro. They can assess whether it's related to the medication or another health issue, and advise on whether to continue, adjust dose, or try an alternative.
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.