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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Cold Symptoms on Mounjaro vs Wegovy
Feeling cold whilst taking Mounjaro is a recognised experience some users report, though it's less commonly discussed than nausea or digestive symptoms. Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only GLP-1 and dual GIP/GLP-1 receptor agonists used for weight management in the UK, and both can affect body temperature regulation in different ways. Understanding how these medications work and how they compare helps you make an informed decision with your prescriber about which might suit you best.
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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.
How Mounjaro and Wegovy Differ in Mechanism and Side Effects
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — it activates two natural hormone pathways simultaneously. This dual mechanism may explain why some users report feeling cold or experiencing chills, as the medication affects metabolic rate and energy expenditure more broadly. In the SURMOUNT clinical trials, Mounjaro participants reported side effects including fatigue and temperature sensitivity, though these typically occur during dose titration.
Wegovy (semaglutide) is a GLP-1 receptor agonist only — it activates a single hormone pathway. It works primarily through appetite suppression and slowing gastric emptying. Whilst Wegovy can cause fatigue and body aches, feeling cold is reported less frequently than with Mounjaro.
- Mounjaro: dual GIP+GLP-1 mechanism, stronger metabolic effects
- Wegovy: single GLP-1 mechanism, more targeted appetite control
- Both cause fatigue; Mounjaro may have more thermoregulation effects
- Individual responses vary significantly between users
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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.
Which Medication Is Right for You? Prescriber Assessment
The choice between Mounjaro and Wegovy is determined by your GP or prescriber through clinical assessment — not by individual side effect preferences alone. Your prescriber will consider your medical history, current medications, BMI, weight-related health conditions, and personal tolerance. If you experience cold sensitivity on one medication, your prescriber may adjust your dose, pause titration, or discuss switching to the alternative — but this decision must be made in consultation with them, not independently.
Both medications require a UK prescription and are available through NHS specialist weight management services or private online prescribing following clinical assessment. Use our free GLP-1 weight loss calculator to understand projected outcomes at different doses, and discuss any temperature-related symptoms with your healthcare provider promptly.
- 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 on Mounjaro a sign I should stop taking it?
Feeling cold during Mounjaro treatment is not necessarily a reason to stop. Many side effects, including cold sensitivity, are temporary and often improve as your body adjusts. However, always discuss persistent symptoms with your prescriber — they may adjust your dose, slow your titration, or recommend pausing treatment temporarily. Never stop a prescription medication without medical guidance.
Why does Mounjaro make some people feel cold?
Mounjaro's dual GIP+GLP-1 mechanism affects metabolic rate and energy expenditure more broadly than GLP-1 alone. This can alter how your body regulates temperature. Additionally, reduced food intake and weight loss can lower body temperature naturally. Individual response varies — some users experience cold sensitivity, others do not.
Is Wegovy less likely to cause cold symptoms than Mounjaro?
Feeling cold is reported less frequently with Wegovy than Mounjaro, possibly because it has a single mechanism (GLP-1 only) rather than dual GIP+GLP-1. However, individual responses vary significantly. Some Wegovy users do report cold sensitivity, whilst some Mounjaro users experience none. Your personal response cannot be predicted in advance.
Can I take anything to manage cold sensitivity on Mounjaro?
Simple measures include wearing warmer clothing, staying active, and ensuring adequate nutrition — underfeeding can worsen cold sensitivity. However, do not adjust your medication or diet without discussing it with your GP first. Certain nutritional deficiencies can also affect temperature regulation, so your prescriber may recommend blood work.
If I have a cold, can I still take Mounjaro or Wegovy?
Having a viral cold (common cold) does not typically prevent you taking Mounjaro or Wegovy. However, if you have a fever, severe infection, or are taking antibiotics, inform your prescriber. Illness can affect appetite and nausea differently when combined with GLP-1 medication. Always check with your GP or pharmacist if you're unwell.
Ready to take control of your weight loss journey?
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