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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Burping on Mounjaro vs Wegovy — What's the Difference?
Burping and other digestive side effects are among the most common experiences reported by people taking weight loss injections. Both Mounjaro (tirzepatide) and Wegovy (semaglutide) can cause belching and gas due to how they slow stomach emptying and affect digestion. While both medications work on the GLP-1 pathway, they have different mechanisms that may influence the type and severity of digestive symptoms. Understanding these differences can help you know what to expect and discuss options with your prescriber. Let's explore how burping compares between these two prescription weight loss medications.
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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.
How Mounjaro and Wegovy Cause Burping — The Mechanisms
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways. This dual action affects appetite control and also slows gastric emptying—how quickly food moves from your stomach into your small intestine. Slowed gastric emptying can trap gas in the stomach, leading to burping and bloating. Many people experience burping especially in the first few weeks as their digestive system adjusts.
Wegovy (semaglutide) works as a GLP-1 receptor agonist only, activating a single hormone pathway. It also slows gastric emptying, so burping is a very common side effect. Clinical trial data from the STEP trials showed that gastrointestinal symptoms, including belching, were reported in a significant proportion of participants, particularly at higher doses.
Both medications share this gastric emptying mechanism, so burping is common with both. The key difference: Mounjaro's dual mechanism may affect digestion differently, potentially causing different patterns of gas and burping for some people. Individual responses vary considerably. Use our GLP-1 weight loss calculator to explore how these medications work at different doses.
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Clinical Data and Individual Experience — What the Trials Showed
In the SURMOUNT-1 trial for Mounjaro, burping and belching were reported alongside other gastrointestinal side effects, though they typically improved over time as the body adjusted. Wegovy's STEP trials similarly documented burping as a common but usually temporary symptom. The incidence didn't differ dramatically between the two medications in overall frequency, but some people report different patterns—for example, some experience more burping with Mounjaro whilst others report it more with Wegovy.
The important context: digestive side effects tend to be most pronounced in the first 4–8 weeks, then often improve significantly. If burping persists or becomes bothersome, your prescriber may suggest dose adjustment or temporary dose reduction. Neither medication is "better" for avoiding this side effect—suitability depends on your individual health profile and other factors. Your GP or licensed prescriber will assess which is appropriate for you based on a full clinical assessment, not just side effect profiles.
- 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 burping worse on Mounjaro or Wegovy?
Clinical trials don't show a clear difference in burping frequency between the two. Both cause it as a common side effect due to slowed stomach emptying. Individual experience varies significantly—some people report more burping with one medication than the other. Your prescriber can help identify which might suit you better based on your full health picture.
Why do GLP-1 medications cause burping?
These medications slow how quickly food moves from your stomach into your small intestine (gastric emptying). This can trap gas, leading to burping and bloating. The effect is temporary as your digestive system adjusts, usually within 4–8 weeks. Staying hydrated and eating smaller meals can help reduce symptoms.
Does burping on weight loss injections mean the medication isn't working?
No. Burping and digestive symptoms don't indicate whether the medication is effective for weight loss. These are common side effects that often improve with time. Weight loss results depend on the medication dose, your diet, and physical activity—not on whether you experience burping.
Can I stop burping if I switch from Mounjaro to Wegovy?
Both medications cause burping through similar mechanisms, so switching may not eliminate the symptom. However, some people do experience less burping with one medication than the other. Any switch must be managed by your prescriber and involves specific timing protocols. Individual responses are unpredictable.
When does burping stop on GLP-1 medications?
Most people find burping and digestive symptoms improve significantly after 4–12 weeks as their body adjusts. Some people adjust faster; others take longer. If burping persists beyond 8 weeks or becomes unbearable, discuss with your prescriber about dose adjustment or symptom management strategies.
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