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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Heart Palpitations on Mounjaro — NHS Guidance
Heart palpitations (noticing your heartbeat) have been reported by some people taking Mounjaro (tirzepatide). This is an important symptom to monitor and report to your GP. In the UK, NHS guidance emphasises that any new or unusual cardiac symptoms should be assessed by a healthcare professional rather than managed at home. This guide explains what palpitations mean, when to seek help, and how NHS services assess medication side effects. Always contact your GP or NHS 111 if you experience new chest symptoms or serious palpitations.
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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.
When to Contact Your GP About Palpitations on Mounjaro
Heart palpitations while taking Mounjaro should be reported to your prescribing GP or specialist at your NHS weight management service. Seek immediate medical attention via NHS 111 or A&E if you experience:
- Severe chest pain or pressure
- Shortness of breath with palpitations
- Dizziness or fainting
- Palpitations lasting more than a few minutes
- New irregular heartbeat patterns
Mild, occasional palpitations may still warrant a GP appointment, especially if they are new. Your GP can check your heart rate and rhythm, review your Mounjaro dose titration schedule, and determine whether the medication should be continued or adjusted. The MHRA (Medicines and Healthcare products Regulatory Agency) monitors safety reports for all medications, including Mounjaro, and your report contributes to this surveillance.
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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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NHS Access vs Private Prescribing for Mounjaro
If you receive Mounjaro through an NHS specialist weight management service, your prescriber and multidisciplinary team monitor side effects as part of routine follow-up. Cardiac symptoms are documented and discussed at each appointment. The NHS uses structured eligibility criteria (BMI ≥30, or BMI 27–29.9 with weight-related health conditions) to ensure medication is prescribed to appropriate candidates.
If prescribed privately, ensure your prescriber has access to your full medical history, including any cardiac risk factors or previous heart symptoms. Always report palpitations to the prescriber who issued your prescription—they can advise whether to continue, pause, or adjust your Mounjaro KwikPen doses. Both NHS and private prescribers have professional obligations to monitor and document adverse effects.
- 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.
Are heart palpitations a common side effect of Mounjaro?
Palpitations are not listed as very common or common side effects in clinical trials or the product information. However, individual experiences vary and any new cardiac symptom should be reported to your GP. Your healthcare team can assess whether palpitations are related to Mounjaro, other medical conditions, or other medications you take.
Should I stop taking Mounjaro if I have palpitations?
Do not stop Mounjaro without medical advice. Contact your GP or NHS specialist immediately to discuss the symptom. Your prescriber will assess severity, your medical history, and whether the benefit of continuing outweighs any risk. Stopping suddenly may affect your weight management plan and requires clinical guidance.
Can Mounjaro trigger underlying heart conditions?
Mounjaro can cause changes in heart rate and blood pressure in some individuals. If you have a personal or family history of cardiac disease, irregular heartbeat, or high blood pressure, discuss this fully with your prescriber before starting. NHS specialist services assess cardiac risk as part of eligibility screening.
How does Mounjaro vs Wegovy differ in cardiac side effects?
Both Mounjaro (tirzepatide, dual GIP/GLP-1 agonist) and Wegovy (semaglutide, GLP-1 agonist) can affect heart rate and blood pressure. Clinical trial data shows similar cardiac safety profiles overall, though individual responses vary. Your GP can advise which medication may be safer given your personal cardiac risk profile.
What should I tell my GP about palpitations on Mounjaro?
Tell your GP when palpitations started, how often they occur, how long they last, associated symptoms (chest pain, breathlessness, dizziness), and your Mounjaro dose at onset. This information helps your GP determine causation and guide next steps—whether that's continuing, adjusting dose, switching medication, or ordering cardiac investigation.
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