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
Can Mounjaro Cause Palpitations?
Palpitations are not listed as a common side effect of Mounjaro (tirzepatide) in UK clinical trials or MHRA safety data. However, some people taking this GLP-1 and GIP receptor agonist medication may experience heart-related sensations. Understanding what to expect and when to contact your GP is important if you're considering this prescription weight loss injection in the UK. This guide explains the evidence and what the NHS recommends.
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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 Evidence Shows About Mounjaro and Heart Palpitations
Palpitations are not a documented common or very common side effect of Mounjaro in the SURMOUNT clinical trials or MHRA safety monitoring data. The most frequently reported side effects are gastrointestinal — nausea, diarrhoea, vomiting, and constipation — which occur in more than 1 in 10 people.
However, some cardiovascular monitoring is relevant: Mounjaro's dose titration process (starting at 2.5 mg and increasing weekly) means your body adjusts gradually, reducing sudden metabolic shifts. If you experience rapid heartbeat, chest discomfort, or irregular heart rhythms while taking tirzepatide, these should be reported to your GP immediately — they may indicate a separate cardiovascular issue unrelated to Mounjaro itself.
- Palpitations are not listed in common side effects
- Gastrointestinal side effects are most frequent
- Individual responses vary — some people may feel more aware of their heartbeat due to gradual weight management or dehydration
- Always inform your prescriber of any existing heart conditions before starting
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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.
When to Seek Medical Advice and NHS Guidance
If you experience persistent palpitations, chest pain, shortness of breath, or dizziness while taking Mounjaro, contact your GP or NHS 111 immediately. These symptoms warrant urgent evaluation regardless of medication. Before starting tirzepatide on an NHS tier 3 specialist service or through private prescription, you'll have a clinical assessment that includes cardiovascular history — this helps identify individuals at higher risk.
Weight loss itself can sometimes cause palpitations in susceptible people due to fluid shifts or electrolyte changes, not the medication directly. Your GP can distinguish between medication-related effects and other causes. Using our free GLP-1 weight loss calculator can help you understand projected changes so you and your prescriber can plan appropriate monitoring.
- 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 known side effect of Mounjaro in the UK?
No, palpitations are not listed as a common or very common side effect in MHRA safety data or the SURMOUNT clinical trials. The most frequent side effects are gastrointestinal. However, individual experiences vary, and any new cardiac symptoms should be reported to your GP.
Should I avoid Mounjaro if I have a history of heart problems?
Not necessarily, but you must inform your prescriber of any existing cardiovascular conditions before starting. A clinical assessment will evaluate your suitability. Some people with heart conditions can safely take Mounjaro under medical supervision, whilst others may need an alternative.
What should I do if I experience palpitations whilst taking Mounjaro?
Contact your GP or NHS 111 immediately. Palpitations warrant medical evaluation regardless of whether they're related to Mounjaro. Your GP can assess whether the symptom is medication-related, due to gradual weight management, or an unrelated cardiovascular issue.
Can gradual weight management from Mounjaro cause palpitations?
gradual weight management can sometimes cause palpitations due to fluid shifts or electrolyte changes, though this is not common. This occurs independently of the medication itself. Losing weight at the NHS-recommended rate of 0.5–1 kg per week reduces this risk.
Is Mounjaro safe if I'm already taking heart medication?
Mounjaro can be used alongside many heart medications, but your prescriber must review all current medications before starting. Some interactions are possible. Always provide a complete list of medications when applying for a Mounjaro prescription.
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.