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 Cause Palpitations?
Palpitations are not listed as a common side effect of Mounjaro (tirzepatide) in UK clinical data, but heart rate changes can occur in some users. If you experience palpitations, chest discomfort, or unusual heartbeat whilst taking Mounjaro, it's important to contact your GP immediately. This guide explains what's known about Mounjaro and heart health, who should be cautious, and when to seek urgent medical advice.
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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.
What the Clinical Evidence Shows About Mounjaro and Heart Health
In the SURMOUNT clinical trials, palpitations were not reported as a very common or common side effect of Mounjaro. However, some users do report heart rate awareness or palpitation-like sensations. These are not the same as serious heart rhythm problems (arrhythmia), which are rare with tirzepatide.
What we know: Mounjaro works by activating GLP-1 and GIP receptors, which can affect heart rate slightly. gradual weight management itself can sometimes cause temporary heart rate increases as your body adapts. If you have a history of heart conditions, high blood pressure, or take medications affecting heart rate, your prescriber will assess this during your clinical assessment before issuing a Mounjaro KwikPen prescription.
The UK regulatory body (MHRA) has not identified palpitations as a safety concern specific to tirzepatide, unlike some other weight loss medications. Always report any chest symptoms to your GP.
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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.
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When to Seek Medical Attention and How to Access Mounjaro Safely in the UK
Seek urgent medical attention if you experience:
- Severe chest pain or pressure
- Persistent palpitations lasting more than a few minutes
- Shortness of breath with heart palpitations
- Dizziness or fainting with heart symptoms
- Any new or worsening arrhythmia
Before starting Mounjaro, you'll have a clinical assessment (NHS or private) where your prescriber reviews your medical history, current medications, and cardiovascular risk factors. This is why prescription-only status matters—it ensures appropriate screening. If you have concerns about your heart health and Mounjaro eligibility, discuss this with your GP or during your online consultation with a UK-licensed prescriber.
- 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.
Are palpitations a common side effect of Mounjaro?
Palpitations are not listed as a common side effect in UK clinical data. Some users report heart rate awareness, but serious arrhythmias are rare. Always report any chest discomfort to your GP immediately, regardless of rarity.
Can Mounjaro cause heart rhythm problems?
Serious heart rhythm problems are not a recognised safety signal for tirzepatide (Mounjaro). However, weight loss itself can temporarily increase heart rate awareness. Your prescriber will assess cardiovascular risk before prescribing.
Who should be cautious about Mounjaro and heart health?
People with a history of heart disease, high blood pressure, or arrhythmia should inform their prescriber during clinical assessment. Those taking certain heart medications may need dose adjustments or closer monitoring.
How do I access Mounjaro safely in the UK?
Through NHS specialist weight management services (tier 3) or a private online consultation with a UK-licensed prescriber. Both routes include a clinical assessment to ensure Mounjaro is appropriate for your individual health profile.
What should I do if I develop palpitations whilst on Mounjaro?
Contact your GP or call NHS 111 immediately if palpitations are new, persistent, or severe. For mild, brief heart rate awareness, inform your prescriber at your next appointment. Never stop Mounjaro suddenly without medical guidance.
Ready to take control of your weight loss journey?
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