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
Can Mounjaro Affect Your Heart?
Mounjaro (tirzepatide) is a prescription-only weight management injection licensed in the UK. Many people ask whether it affects heart health. The good news is that clinical trials showed no increased heart attack or stroke risk in people taking Mounjaro. However, because it's a newer medication, it carries MHRA additional monitoring status (Black Triangle ▼). Your prescriber will assess your individual cardiovascular risk before offering this medication. If you have existing heart conditions, discuss this directly with your GP or NHS specialist service.
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Calculate Your BMI Instantly
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.
Mounjaro and Cardiovascular Safety — What the Evidence Shows
SURMOUNT clinical trials did not show increased cardiovascular risk in people taking tirzepatide (Mounjaro) compared to placebo over 72 weeks. In fact, many participants experienced improvements in blood pressure and blood sugar control—both important for heart health. Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it works differently from other weight loss injections like Wegovy (semaglutide).
However, the MHRA has assigned Black Triangle (▼) status to Mounjaro, which means it receives additional monitoring for safety signals. This is routine for newer medicines and does not mean it is unsafe—rather, healthcare professionals must report any adverse effects promptly so the regulator can monitor real-world use.
- Weight loss alone improves heart health by reducing strain on the cardiovascular system
- Mounjaro may help lower blood pressure in some people
- Benefits for blood sugar control reduce diabetes-related heart disease risk
- Individual responses vary—your prescriber will discuss your personal risk profile
If you have a history of heart attack, stroke, or heart disease, your prescriber may assess you more carefully before prescribing. This is not a contraindication but requires individual evaluation using our free BMI calculator and assessment of your overall health picture.
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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.
Who Should Be Careful — NHS Prescribing Context
The NHS recommends caution if you have:
- A personal history of heart attack or stroke
- Severe heart disease or heart failure
- Uncontrolled high blood pressure (above 180/110 mmHg)
- Existing use of insulin or certain diabetes medications that increase hypoglycaemia risk
Mounjaro is prescribed through NHS tier 3 specialist weight management services following full clinical assessment. Private prescribers also conduct cardiovascular screening. Either route requires a prescription and professional evaluation. If you're concerned about how Mounjaro might affect your heart specifically, ask your GP for a referral to specialist services, or speak with a prescriber during a private consultation. They can review your individual risk factors, current medications, and medical history to advise whether this medication is suitable for you—not all people are candidates, and that is normal and safe practice.
- 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 cause heart attacks or strokes?
No—the SURMOUNT clinical trials found no increased risk of heart attack or stroke with Mounjaro compared to placebo. However, because it is newer, the MHRA monitors it closely (Black Triangle status). Always disclose your full medical history to your prescriber for personalised assessment.
Can I take Mounjaro if I have high blood pressure?
Yes, many people with high blood pressure take Mounjaro safely. In fact, weight loss and some GLP-1 effects may help lower blood pressure. However, your prescriber must review your current blood pressure levels and medications before prescribing. Discuss this with your GP or prescriber.
Is Mounjaro safe compared to Wegovy (semaglutide) for my heart?
Both are prescription-only weight management injections with good safety profiles in clinical trials. Mounjaro is a dual GIP/GLP-1 agonist, while Wegovy is GLP-1 only. Neither has shown increased heart risk. Your prescriber can advise which suits your individual health profile best.
What should I tell my GP about my heart before starting Mounjaro?
Tell your GP or prescriber about any history of heart attack, stroke, heart disease, arrhythmia, or uncontrolled high blood pressure. Mention all current medications and any family history of early heart disease. This helps them assess whether Mounjaro is appropriate for you.
Can Mounjaro help reduce my heart disease risk?
Yes—weight loss itself reduces cardiovascular strain. Many people taking Mounjaro see improvements in blood pressure and blood sugar control, both of which lower heart disease risk. However, Mounjaro is a weight management aid, not a heart medication. Use it alongside healthy diet and exercise for best results.
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.