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 Increase Heart Rate? What the Clinical Evidence Shows
Heart rate changes are not listed as common side effects of Mounjaro in UK clinical data, though individual responses vary. Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are GLP-1 receptor agonist medications that may affect heart rate in some users through different mechanisms. Understanding how these prescription weight loss injections work and what clinical trials revealed is important for anyone considering treatment. Your GP or prescriber will assess your individual suitability and monitor you throughout treatment.
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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.
Heart Rate Effects: Mounjaro vs Wegovy Clinical Comparison
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist. In SURMOUNT clinical trials, heart rate changes were not reported as a common side effect, though some users experienced palpitations or tachycardia rarely. The dual mechanism may affect heart rate differently than single GLP-1 agents.
Wegovy (semaglutide) is a GLP-1 agonist only. STEP trials similarly did not list heart rate increase as a very common side effect, though dizziness and fatigue were common. These can indirectly affect how you perceive heart rate.
- Both medications slow gastric emptying, which may temporarily affect heart rate in some individuals
- gradual weight management itself can influence resting heart rate
- Dehydration from nausea or vomiting may increase perceived heart rate
- Pre-existing heart conditions require prescriber assessment before either medication
Neither drug is insulin and neither directly stimulates the heart muscle. Any heart rate concerns should be reported to your GP immediately.
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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.
Prescriber Assessment and Individual Suitability
Whether you're prescribed Mounjaro or Wegovy depends on clinical assessment of your full health history, not on heart rate effects alone. Both are prescription-only medicines available in the UK through NHS specialist weight management services or private prescribers following online clinical assessment.
Your prescriber will ask about:
- History of heart conditions, arrhythmias, or high blood pressure
- Current medications that might interact
- Family history of cardiovascular disease
- Your BMI, weight-related comorbidities, and eligibility
If you have concerns about heart rate changes during treatment, contact your GP immediately. Use our free GLP-1 weight loss calculator to understand projected outcomes, and track your health progress with our progress tracker throughout your treatment 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 heart palpitations?
Heart palpitations are not listed as a common side effect in UK clinical data for Mounjaro. However, individual responses vary. If you experience palpitations, chest pain, or irregular heartbeat while taking Mounjaro, contact your GP or seek urgent medical attention immediately. Always report any heart-related symptoms to your prescriber.
Is Mounjaro safe if I have high blood pressure?
Mounjaro may be prescribed to people with high blood pressure if it's well-controlled and benefits outweigh risks. Your prescriber will assess your blood pressure history and current management. However, your GP must know about your hypertension before starting any GLP-1 medication. Regular monitoring is essential.
Do Mounjaro and Wegovy affect heart rate differently?
Both are GLP-1 receptor agonists but Mounjaro is dual GIP+GLP-1. Clinical trials for both showed minimal heart rate issues. Individual responses vary based on your health, weight loss speed, and hydration. Your prescriber will monitor you and can discuss specific concerns about your medical history.
What should I do if my heart rate increases on Mounjaro?
If you notice persistent increases in resting heart rate, palpitations, or chest discomfort, contact your GP promptly. These could indicate dehydration, gradual weight management effects, or a response to the medication. Your prescriber may adjust your dose, pause treatment, or recommend further cardiac assessment depending on severity.
Is Mounjaro suitable for people with heart conditions?
Mounjaro is not automatically contraindicated for heart conditions, but requires careful prescriber assessment. Conditions like heart failure, arrhythmias, or recent heart attack need specialist evaluation. Your GP or cardiologist must review your case before starting Mounjaro. Never start without full disclosure of your cardiac history.
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.