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
Mounjaro and Heartburn — Managing Symptoms in the UK
Heartburn is a common side effect reported by people taking Mounjaro (tirzepatide) in the UK. This indigestion-like discomfort occurs in the chest or stomach and may happen as your body adjusts to the medication. Understanding what causes it, how to manage it, and how to access Mounjaro through either NHS or private prescription can help you make an informed decision about this weight management treatment. MyWeightCheck provides evidence-based guidance to help you navigate treatment options and costs.
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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.
Managing Mounjaro Heartburn — Practical Strategies
Heartburn, medically known as gastro-oesophageal reflux disease (GORD), affects up to 1 in 10 people taking Mounjaro during the early weeks of treatment. It usually improves as your body adapts to the medication.
Management strategies include:
- Eating smaller, more frequent meals rather than large ones
- Avoiding triggering foods (spicy, fatty, citrus, chocolate)
- Staying upright for at least 2–3 hours after eating
- Waiting at least 30 minutes after meals before lying down
- Taking antacids or over-the-counter proton pump inhibitors (PPIs) — discuss with your GP first
- Staying hydrated throughout the day
If heartburn persists beyond the first month or becomes severe, contact your prescriber. They may suggest dose timing adjustments or additional medication to manage symptoms whilst you continue tirzepatide treatment.
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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.
Accessing Mounjaro in the UK — NHS vs Private Routes
NHS Route: Mounjaro is available through specialist tier 3 weight management services following NICE approval. You'll need a GP referral and assessment by a multidisciplinary weight management team. Availability varies significantly by region, and waiting lists can extend 6–12 months in many areas.
Private Route: GPhC-registered online pharmacies offer Mounjaro following a consultation with a UK-licensed prescriber. This route bypasses NHS waiting lists. Typical costs range from £129–£320 per month depending on dose. An online assessment takes 10–15 minutes; prescriptions are issued within 24 hours if approved. No referral needed — perfect for those wanting faster access or living in areas with limited NHS provision.
- 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.
Is heartburn a serious side effect of Mounjaro?
Heartburn is common but usually mild and temporary. It typically improves within 2–4 weeks as your body adjusts. However, if it's severe, persistent, or accompanied by difficulty swallowing or chest pain, contact your GP or prescriber immediately to rule out other conditions.
Can I take antacids whilst using Mounjaro?
Yes, over-the-counter antacids are generally safe to use alongside Mounjaro. Calcium carbonate or magnesium-based antacids work quickly. Proton pump inhibitors (PPIs) like omeprazole can also help. Always mention antacid use to your prescriber, as some medications may affect Mounjaro's effectiveness if taken simultaneously.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £129 at the starting 2.5mg dose to £320+ at the maximum 15mg dose per month. Some providers offer bundle packages. NHS prescriptions are free, but NHS access requires referral and may involve lengthy waiting lists depending on your region.
How do I get a private Mounjaro prescription online?
Register with a GPhC-registered online pharmacy offering Mounjaro. Complete a brief health questionnaire (10–15 minutes). A UK-licensed prescriber reviews your information and medical history. If approved, your prescription is sent to the pharmacy's dispensary. Delivery typically takes 2–3 working days.
What's the difference between Mounjaro and Wegovy for heartburn risk?
Both are GLP-1-based medications; Mounjaro is a dual GIP/GLP-1 agonist whilst Wegovy (semaglutide) activates GLP-1 only. Heartburn rates are similar in clinical trials. Mounjaro may produce slightly stronger appetite suppression. Your prescriber can help determine which suits your individual health profile and symptom tolerance.
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.