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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Why Does Mounjaro Increase Heart Rate?
Mounjaro (tirzepatide) is a prescription-only weight management injection that may cause a slight increase in heart rate for some people. This side effect is generally mild and often temporary, particularly during the initial stages or when doses are increased. If you're considering Mounjaro as part of your weight management journey, understanding how it affects your cardiovascular system is important. This guide explains why heart rate changes occur, what to expect, and when to contact your GP. Always consult your healthcare professional about any concerns specific to your individual health.
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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.
How Mounjaro Affects Heart Rate
Mounjaro is a dual GIP and GLP-1 receptor agonist — it activates two natural hormone pathways that regulate appetite and metabolism. When these pathways are activated, your body may experience several changes: increased metabolic activity, changes in blood pressure regulation, and a modest increase in heart rate in some individuals. During clinical trials like SURMOUNT-1, heart rate increases were observed but were typically modest and often resolved as the body adjusted to the medication. The elevation is usually more noticeable during dose titration — when you're increasing your Mounjaro dose from 2.5 mg up to 5 mg, 7.5 mg, 10 mg, or higher.
Additionally, weight loss itself can affect heart rate. As your body loses weight and becomes more active, your cardiovascular system adapts, which may initially cause slight heart rate fluctuations. Most people who experience heart rate changes on Mounjaro find these effects stabilise within weeks as their body adapts to the medication.
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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 Monitor and Seek Help
Heart rate monitoring is important if you're taking Mounjaro. A normal resting heart rate for adults is typically 60–100 beats per minute. If you notice your resting heart rate increases significantly (more than 20 bpm above your baseline), or if you experience palpitations, chest pain, dizziness, or shortness of breath, contact your GP promptly.
Keep a simple record of your resting heart rate in the morning — use our free progress tracker to log your weight and health changes alongside other observations. Report any persistent or concerning heart rate changes to your prescriber, especially if they coincide with dose increases. Your GP may adjust your dose or recommend additional monitoring via ECG.
- 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.
Does everyone experience heart rate increases on Mounjaro?
No. Not everyone experiences heart rate changes on Mounjaro. Clinical trial data shows the effect varies between individuals. Some people notice no change at all, while others experience modest increases. Your age, fitness level, existing cardiovascular health, and individual metabolism all influence whether you'll notice this side effect. Always discuss your personal risk factors with your prescriber.
Is a higher heart rate on Mounjaro dangerous?
A modest increase in heart rate (5–10 bpm) is usually not dangerous and often resolves as your body adjusts. However, significant increases, palpitations, chest pain, or accompanying dizziness warrant immediate GP consultation. Your prescriber may perform an ECG or other monitoring to ensure the changes are safe for your individual health profile. Never ignore concerning cardiac symptoms.
Can I take Mounjaro if I have high blood pressure or heart disease?
Mounjaro can be prescribed to people with cardiovascular conditions, but eligibility requires careful assessment. Your GP or prescriber will review your medical history, current medications, and baseline heart rate before deciding if Mounjaro is appropriate. Some heart conditions may be contraindications. Always declare all existing health conditions during your clinical assessment.
How does Mounjaro compare to Wegovy regarding heart rate effects?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1-only agonist. Clinical data suggests both may cause mild heart rate increases, though direct comparisons are limited. Mounjaro may have slightly different cardiovascular effects due to its dual mechanism. Your prescriber can discuss which option might be more suitable based on your heart rate response and overall health.
Will my heart rate return to normal after stopping Mounjaro?
Yes. Heart rate elevations caused by Mounjaro typically resolve once you stop taking the medication, usually within days to a few weeks. However, if you've lost significant weight while on Mounjaro, your resting heart rate may remain slightly lower than before due to improved cardiovascular fitness — which is generally a positive health outcome.
Ready to take control of your weight loss journey?
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