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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Does Mounjaro Increase Heart Rate?
Mounjaro (tirzepatide) can affect heart rate in some people, though significant increases are relatively uncommon. Some patients report a faster heartbeat, whilst others experience no change at all. If you're considering Mounjaro as a weight management option in the UK, understanding how it may affect your cardiovascular health is important. This guide covers what NHS guidance says, what clinical trials showed, and when you should contact your GP about heart rate changes.
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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 Clinical Evidence Shows
In the SURMOUNT-1 clinical trial, which tested tirzepatide in over 2,500 participants, heart rate increases were reported but occurred at similar rates in both the treatment and placebo groups. Most heart rate changes were mild and did not require treatment discontinuation. However, some individuals did experience a notable increase in resting heart rate—typically 2–5 beats per minute higher than baseline.
The NHS and MHRA (Medicines and Healthcare products Regulatory Agency) have reviewed this data as part of Mounjaro's Black Triangle ▼ status, meaning additional monitoring is ongoing. If you're prescribed Mounjaro on the NHS through a tier 3 specialist weight management service, your prescriber will monitor your heart rate and blood pressure at baseline and during treatment. Ask your GP or prescriber to record your baseline heart rate so you can track any changes yourself.
Important factors: heart rate changes may be related to weight loss itself, reduced food intake, or the medication's mechanism. Individual responses vary significantly.
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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 Contact Your GP
Contact your GP immediately if you experience a very rapid heartbeat (tachycardia), chest pain, shortness of breath, dizziness, or fainting whilst taking Mounjaro. These symptoms may indicate a more serious condition requiring urgent review. Additionally, if your resting heart rate increases by more than 10–15 beats per minute or you feel consistently unwell, discuss this with your prescriber—you may need a dose adjustment or discontinuation.
If you have a pre-existing heart condition, arrhythmia, or have previously experienced heart problems, inform your prescriber before starting Mounjaro. Your NHS specialist service should conduct a full cardiovascular assessment before prescribing. Never ignore persistent symptoms—your health comes first, and your GP can advise whether Mounjaro remains appropriate for you.
- 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 Mounjaro raise heart rate in everyone?
No. Clinical trial data showed heart rate increases occurred at similar rates in Mounjaro and placebo groups. Many people experience no change in heart rate at all. Individual responses vary based on baseline fitness, weight loss rate, and personal metabolism.
Is a faster heartbeat dangerous with Mounjaro?
Mild increases (2–5 bpm) are generally not dangerous. However, sudden or severe increases, chest pain, or shortness of breath require urgent GP assessment. The MHRA monitors Mounjaro closely due to its Black Triangle status. Always report significant changes to your prescriber.
How does Mounjaro's heart rate effect compare to Wegovy?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are GLP-1 (or GIP/GLP-1) medications and may cause mild heart rate changes. Clinical trial data shows similar cardiovascular safety profiles. Your GP can advise which is more appropriate for your individual health profile.
Can I take Mounjaro if I have high blood pressure or heart disease?
This requires careful assessment by your NHS prescriber or GP. Mounjaro is not automatically contraindicated in cardiovascular disease, but a full cardiovascular evaluation is essential before starting. Your specialist weight management service will review your medical history and monitor you closely.
Should I check my heart rate whilst on Mounjaro?
Yes, monitoring your resting heart rate is reasonable. Take it at the same time each day, in a relaxed state, before getting out of bed. If you notice a consistent increase of more than 10–15 bpm or experience symptoms like palpitations or dizziness, contact your GP to discuss whether continued use is appropriate.
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