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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Mounjaro and Palpitations vs Wegovy
Heart palpitations (feeling your heartbeat) are a potential side effect of both Mounjaro (tirzepatide) and Wegovy (semaglutide), though they're not among the most common. Both medications are prescription-only GLP-1 or dual GIP/GLP-1 receptor agonists used for weight management in the UK. This guide compares the two medications factually, explains the cardiovascular context, and helps you understand why individual suitability is always assessed by a prescriber following clinical evaluation.
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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 vs Wegovy: Clinical Trial Data and Mechanism Differences
Mechanism: Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, whereas Wegovy (semaglutide) is a GLP-1 agonist only. This difference in mechanism may influence side effect profiles, though clinical evidence specific to palpitations is limited in both cases.
- SURMOUNT trials (Mounjaro): Palpitations were not listed as a common or very common side effect in the primary trial data. Cardiovascular events were monitored, and rates were comparable to placebo groups.
- STEP trials (Wegovy): Similarly, palpitations were not prominently reported. Both medications have cardiovascular safety monitoring data from large clinical trials.
Both medications may cause nausea, diarrhoea, and constipation more frequently than palpitations. Individual cardiovascular risk factors and baseline heart conditions influence prescriber decision-making around medication suitability.
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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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Prescriber Assessment and Individual Suitability
Whether you're eligible for Mounjaro or Wegovy depends on your personal health history, including any existing heart conditions, blood pressure, and other cardiovascular risk factors. A UK-licensed prescriber will assess which medication—if either—is most appropriate for you during a clinical consultation.
If you have a history of palpitations, arrhythmia, or heart disease, inform your prescriber before starting any weight loss medication. Both Mounjaro and Wegovy require ongoing monitoring. If you experience new or worsening palpitations while taking either medication, contact your GP or prescriber immediately. Track your wellbeing with our free progress tracker to log any symptoms alongside your weight loss journey.
- 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.
Can Mounjaro cause palpitations?
Palpitations are not listed as a common side effect of Mounjaro in clinical trials, though any medication can affect individuals differently. If you experience palpitations while taking Mounjaro, contact your prescriber or GP immediately. Your cardiovascular health will be assessed before prescription.
Is Wegovy safer than Mounjaro for heart palpitations?
Both medications have similar cardiovascular safety profiles from clinical trials. Neither lists palpitations as a frequently reported side effect. Individual suitability depends on your personal health history, not on comparing the two medications directly.
What should I do if I get palpitations on Mounjaro or Wegovy?
Stop taking the medication and contact your GP or prescriber immediately. Do not attempt to self-diagnose. Palpitations can indicate various conditions, and your prescriber needs to assess whether the medication caused them or whether another medical issue requires attention.
Will my GP monitor my heart health on Mounjaro or Wegovy?
A prescriber will assess your cardiovascular health before prescribing either medication. Ongoing monitoring depends on your individual risk factors and baseline health. Always inform your prescriber about any existing heart conditions, high blood pressure, or family history of cardiovascular disease.
How do I know if I'm eligible for Mounjaro or Wegovy in the UK?
You're potentially eligible if you have a BMI of 30 or above, or 27 or above with weight-related health conditions. A UK-licensed prescriber will assess your full health history during a clinical consultation, including cardiovascular factors, before deciding which—if any—medication is suitable for you.
Ready to take control of your weight loss journey?
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