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
Does Mounjaro Make You Cold?
Feeling cold is not listed as a common side effect of Mounjaro (tirzepatide) in UK clinical data, but some users report temperature sensitivity. This guide explains what the evidence shows, why it might happen, and when to contact your GP. Mounjaro is a prescription-only weight management injection that works by activating GIP and GLP-1 hormone pathways. If you're experiencing persistent cold sensations, it's important to understand whether this is related to your medication or another factor.
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.
What the Clinical Evidence Shows About Temperature and Mounjaro
In the SURMOUNT clinical trials that led to Mounjaro's approval in the UK, feeling cold was not reported as a common or very common side effect. The most frequently reported side effects included nausea, diarrhoea, vomiting, and constipation. However, some patients receiving tirzepatide have reported feeling unusually cold or experiencing temperature sensitivity.
This could be explained by several factors: gradual weight management itself can make you feel colder (your body has less insulation), reduced appetite may mean lower calorie intake affecting body temperature regulation, or individual sensitivity to the medication. Weight loss medications work on appetite centres in the brain, which are connected to thermoregulation pathways, so indirect effects are theoretically possible.
If you're taking Mounjaro and experiencing persistent cold sensations, it's worth keeping a symptom diary to identify patterns. Use our GLP-1 weight loss calculator to track your progress and discuss any side effects with your prescriber at your next review.
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.
When to Contact Your GP or Prescriber
Contact your GP or the prescriber managing your Mounjaro prescription if: you experience severe or persistent chills, your temperature drops unusually (hypothermia symptoms), the cold sensation is accompanied by other concerning symptoms like dizziness or chest pain, or the symptom is significantly affecting your quality of life.
Do not stop taking Mounjaro without speaking to your prescriber first. They can assess whether the symptom is related to the medication, your weight loss, or another cause. Your prescriber may adjust your dose, recommend lifestyle changes (warmer clothing, increased warm beverages), or suggest alternative treatments if needed. Always discuss any concerns about side effects openly—they're here to help ensure your treatment is both effective and safe.
- 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 common side effect of Mounjaro in the UK?
Feeling cold is not listed as a common or very common side effect in SURMOUNT clinical trials. However, some patients report temperature sensitivity. This may be due to gradual weight management, reduced calorie intake, or individual medication sensitivity rather than Mounjaro directly causing cold sensations.
Why might Mounjaro make you feel colder?
Several factors could explain this: gradual weight management means less body insulation, reduced appetite may lower calorie intake (affecting metabolic heat production), and the medication's effect on appetite centres in the brain could indirectly influence temperature regulation. Weight loss itself commonly causes people to feel colder.
Should I stop taking Mounjaro if I feel unusually cold?
Do not stop Mounjaro without speaking to your prescriber. Contact your GP or prescriber to discuss the symptom. They can assess whether it's medication-related, weight loss-related, or another cause, and recommend next steps. Stopping suddenly isn't recommended.
How can I stay warmer while taking Mounjaro?
Wear warmer clothing, drink warm beverages, ensure you're eating enough calories alongside your weight loss plan, and stay active (exercise generates body heat). If cold sensations persist despite these measures, contact your prescriber for further evaluation.
Is feeling cold different between Mounjaro and Wegovy?
Both Mounjaro and Wegovy are GLP-1 pathway medications (Mounjaro is dual GIP/GLP-1). Temperature sensitivity isn't a documented common side effect of either, but individual experiences vary. Your prescriber can discuss any differences relevant to your situation.
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.