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 Heart Rate โ What You Need To Know
Mounjaro (tirzepatide) is a prescription-only weight management injection that may affect heart rate in some users. The UK MHRA has this listed as a potential side effect requiring monitoring. This guide explains how Mounjaro can influence your heart rate, what the clinical evidence shows, and when you should contact your GP. It's important to understand that individual responses vary, and your prescriber will assess whether this medication is suitable for your personal health situation.
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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/mยฒ).
While BMI isn't a perfect measure โ it doesn't account for muscle mass, bone density, or fat distribution โ 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 โ 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 May Affect Heart Rate
Mounjaro is a dual GIP and GLP-1 receptor agonist that works by activating natural hormone pathways involved in appetite control and metabolism. Some users report changes in heart rate or heart palpitations, though these are not among the most common side effects reported in clinical trials.
Heart rate changes with Mounjaro can occur in several ways:
- Tachycardia (increased heart rate) โ some patients experience a faster heart rate, particularly during dose escalation
- Palpitations โ a noticeable awareness of your heartbeat, which may feel irregular or fluttering
- Bradycardia (slower heart rate) โ less common but reported in some cases
These changes are typically mild and transient, though anyone experiencing persistent or concerning heart rate changes should contact their GP immediately. The UK prescribing information for Mounjaro specifically advises monitoring heart rate, particularly if you have a history of cardiovascular disease or are taking heart medications.
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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 โ all stored privately in your browser.
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NHS Prescribing And Cardiac Monitoring
When Mounjaro is prescribed through NHS tier 3 specialist weight management services, your GP and specialist team will review your cardiovascular history before starting treatment. If you have a history of high blood pressure, heart disease, or arrhythmia, your clinician may recommend baseline heart rate and blood pressure monitoring before and during treatment.
The NHS approach emphasises that weight loss itself often improves heart health โ reducing blood pressure, improving cholesterol, and lowering strain on the cardiovascular system. However, if you notice persistent palpitations, chest discomfort, or significant heart rate changes after starting Mounjaro or dose escalation, contact your GP immediately. Never adjust or stop your dose without medical guidance. Your prescriber can assess whether the medication should be continued, paused, or switched.
Use our free BMI calculator above to understand your starting point, and our GLP-1 weight loss calculator to explore projected outcomes with Mounjaro at different doses.
- 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 โ 5mg โ 7.5mg โ 10mg โ 12.5mg โ 15mg
- GLP-1 receptor agonist
- Up to 15โ17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg โ 0.5mg โ 1mg โ 1.7mg โ 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 | 15โ22.5% | 12โ17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20โ32 weeks | 16โ20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | ยฃ150โยฃ250/month | ยฃ150โยฃ300/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 โ 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 problems?
Mounjaro is not known to cause heart disease, but it may cause temporary changes in heart rate or palpitations in some users. These are usually mild. However, if you have existing heart conditions, your GP must assess suitability before prescribing. Weight loss itself typically improves heart health long-term.
Should I check my heart rate on Mounjaro?
Your GP or prescriber may recommend monitoring your heart rate, especially during dose escalation or if you have cardiovascular risk factors. Simple home monitoring or a wearable device can track this. Report any unusual changes to your healthcare provider.
What should I do if I notice heart palpitations on Mounjaro?
Contact your GP or prescriber immediately. Do not stop your dose without medical guidance. Palpitations may settle as your body adjusts, or your prescriber may recommend pausing, reducing your dose, or switching medication based on your individual situation.
Is Mounjaro safe for people with heart conditions?
Mounjaro can be prescribed to people with stable heart conditions, but requires careful assessment by a prescriber. Your full medical history, current medications, and cardiovascular status will be reviewed. Some conditions may make Mounjaro unsuitable or require additional monitoring.
How long do heart rate changes last on Mounjaro?
Most heart rate changes are temporary and may settle within days to weeks as your body adjusts. However, individual responses vary significantly. If changes persist beyond a few weeks or cause concern, discuss with your GP โ adjustment of dose or medication may be needed.
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.