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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Smelly Burps On Mounjaro vs Wegovy — What's The Difference?
Smelly burps can occur with both Mounjaro (tirzepatide) and Wegovy (semaglutide), though they're not among the most commonly reported side effects. Both medications slow gastric emptying and affect digestion, which may cause unpleasant-smelling burps in some people. The key difference lies in their mechanisms: Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Wegovy is a GLP-1 agonist only. Understanding how these differences might affect your individual experience can help you decide which medication is right for you with your prescriber's guidance.
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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.
How Mounjaro And Wegovy Affect Digestion Differently
Mounjaro (tirzepatide) activates two hormone pathways: GIP (glucose-dependent insulinotropic polypeptide) and GLP-1. This dual mechanism may have different effects on stomach emptying and digestion compared to Wegovy. Some people report digestive symptoms like smelly burps more frequently when taking dual-action medications, though clinical trials did not specifically flag this as a major differentiator.
Wegovy (semaglutide) activates GLP-1 only. It also slows gastric emptying, meaning food stays in your stomach longer. This can cause fermentation and gas production, which may result in smelly or sulphurous burps in some users.
- Both medications are once-weekly injections licensed for weight management in UK adults
- Both require a UK prescription following clinical assessment
- Individual digestive responses vary significantly between people
- Symptoms like burps typically improve over time as your body adjusts to the mounjaro kwikpen dose or Wegovy pen
Clinical trial data from SURMOUNT (Mounjaro) and STEP (Wegovy) trials did not prominently report smelly burps specifically, suggesting it affects a minority of users. Your prescriber can discuss individual tolerability factors with you.
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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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Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Which Medication Might Suit You Better?
Neither Mounjaro nor Wegovy is objectively "better" — suitability depends on your individual health profile, preferences, and response. Both are prescription-only and require a mounjaro nhs nice assessment or private clinical consultation. A UK prescriber will evaluate your mounjaro eligibility uk based on your BMI, health conditions, and medical history.
If you experience smelly burps or other digestive side effects, your prescriber may suggest: adjusting your dose titration schedule, taking smaller meals, drinking more water, or switching to the alternative medication. Most gastrointestinal symptoms improve after the first few weeks as your body adjusts to the mounjaro dose escalation or Wegovy maintenance dose.
- Try our free GLP-1 weight loss calculator to see projected outcomes at different doses
- Use our BMI calculator to check your starting point and treatment eligibility
- Log your side effects in our progress tracker to discuss patterns with your prescriber
- 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 smelly burps a common side effect of Mounjaro?
No. Common Mounjaro side effects include nausea, diarrhoea, and constipation. Smelly or sulphurous burps affect fewer people but may occur due to slowed gastric emptying and fermentation of food in the stomach. Most digestive symptoms improve within 4–8 weeks as your body adjusts.
Does Wegovy cause smelly burps more than Mounjaro?
Clinical trial data doesn't show significant differences between the two. Both are GLP-1-based medications (Mounjaro also activates GIP), and both slow stomach emptying. Individual experiences vary widely. If burps are bothersome, discuss with your prescriber about dose adjustment or switching.
What can I do if I experience smelly burps on either medication?
Eat smaller, more frequent meals; drink plenty of water; avoid foods that ferment easily (refined carbs, sugars); and wait 4–8 weeks for your digestive system to adapt. If symptoms persist or worsen, contact your prescriber — dose adjustment or medication switch may help.
Should smelly burps stop me from taking Mounjaro or Wegovy?
Not necessarily. This side effect is typically mild, temporary, and manageable. Your prescriber may adjust your tirzepatide dose schedule or suggest dietary modifications. Most people find symptoms resolve with time and lifestyle tweaks without stopping treatment.
Can I switch from Mounjaro to Wegovy if I get smelly burps?
Yes, switching between medications is possible under prescriber guidance. However, try dietary changes and dose adjustment first, as symptoms often improve naturally. Any medication switch must be managed by your UK prescriber following clinical assessment.
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.