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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Mounjaro Eggy Burps: What They Are and How to Manage Them
Eggy burps (sulfurous belching) are a reported side effect of Mounjaro (tirzepatide) that some patients experience during treatment. This happens because Mounjaro slows how quickly food leaves the stomach, which can create conditions for sulphur compounds to form. Most commonly reported in the early weeks of treatment, eggy burps usually improve or resolve as your body adjusts to the medication. If you're considering Mounjaro in the UK, understanding this side effect—and how to access the medication cost-effectively—is important for making an informed decision.
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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 Side Effects and Eggy Burps in Context
Eggy burps on Mounjaro occur because the medication slows gastric emptying (how fast food moves from your stomach into the small intestine). This delayed digestion allows bacteria in the gut to produce sulphur compounds, which are released as belching with an unpleasant eggy or rotten smell.
According to clinical trial data, gastrointestinal side effects like nausea, diarrhoea, and constipation are very common with tirzepatide, affecting more than 1 in 10 patients. Eggy burps are less formally documented in trial data but are frequently reported by real-world users. Most patients report this side effect is:
- Most pronounced in weeks 1–4 after starting or increasing dose
- Mild to moderate in severity
- Usually manageable with dietary adjustments (avoid sulphur-rich foods like eggs, broccoli, cabbage)
- Typically reduced or resolved within 2–4 weeks as tolerance builds
If eggy burps persist beyond 4 weeks, inform your prescriber, as they may recommend a slower dose titration or dietary changes.
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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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Accessing Mounjaro in the UK: NHS vs Private Routes
NHS access to Mounjaro: Available through tier 3 specialist weight management services following referral from your GP. NICE has approved tirzepatide for eligible adults, but availability and waiting times vary significantly by region. Many areas have waiting lists measured in months.
Private access: UK-licensed prescribers offer Mounjaro prescriptions through online consultations without NHS referral. After clinical assessment, prescriptions are dispensed by GPhC-registered pharmacies. A Mounjaro prescription (4-week supply) typically costs £129–£250 depending on your current dose. When comparing options, factor in: total cost including any consultation fees, delivery charges, and whether your dose requires monthly or less frequent ordering. Always verify the provider is MHRA-registered and the prescriber is UK-licensed.
- 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.
How long do eggy burps last on Mounjaro?
Most patients report eggy burps peak in the first 2–4 weeks after starting or increasing their dose, then gradually improve. By week 4–8, many experience significant reduction or complete resolution. If they persist beyond 8 weeks, discuss with your prescriber about dose adjustments or dietary strategies.
Can I prevent eggy burps on Mounjaro?
Yes, partly. Avoid high-sulphur foods (eggs, cruciferous vegetables, red meat), eat smaller, more frequent meals, stay hydrated, and consume ginger or peppermint tea. Slowing your eating pace also helps. These strategies reduce conditions that trigger sulphur compound formation in delayed digestion.
What's the difference between Mounjaro and Wegovy for side effects?
Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist, while Wegovy (semaglutide) is a single GLP-1 agonist. Both cause similar gastrointestinal side effects like nausea and constipation, but the dual mechanism of Mounjaro means some patients report different tolerability patterns. Individual experiences vary significantly.
How much does Mounjaro cost privately in the UK?
Private Mounjaro prescriptions typically cost £129–£250 per month depending on your dose (2.5mg to 15mg). Some providers offer dose-specific pricing or bundled packages. Always check what's included: consultation fees, delivery, and follow-up support vary between providers.
Do I need a prescription for Mounjaro in the UK?
Yes, Mounjaro is prescription-only. You cannot buy it without a valid UK prescription from a registered prescriber. You can obtain a prescription through NHS specialist weight management services or private online consultations with a UK-licensed prescriber.
Ready to take control of your weight loss journey?
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