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 and Burping vs Wegovy — What You Need to Know
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only GLP-1 and GIP receptor agonist medications licensed for weight management in the UK. Many people starting these injections report burping, belching, and gas as side effects, though the frequency and severity can vary between individuals and between the two medications. This guide compares how burping presents with each, what the clinical trials showed, and how their different mechanisms may affect digestive symptoms.
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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 Affect Digestion Differently
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two natural hormone pathways. Wegovy (semaglutide) is a GLP-1 receptor agonist only, activating a single pathway. This difference in mechanism may influence digestive side effects, including burping and gas.
Both medications slow gastric emptying — how quickly food leaves your stomach — which can lead to bloating, belching, and increased gas production as your digestive system adjusts. In clinical trials, nausea was the most commonly reported gastrointestinal side effect for both medications, typically occurring in the first 4–8 weeks. Burping and gas are reported less frequently than nausea but remain common, particularly when doses are increased or during the initial weeks of treatment.
Mounjaro's dual mechanism means some patients report slightly different digestive experiences compared to Wegovy, though individual responses vary considerably. Your GP or prescriber can discuss which medication may be more suitable based on your individual health profile and any pre-existing digestive conditions.
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Burping and Side Effects — What the Trials Showed
The SURMOUNT-1 trial (Mounjaro) and STEP-1 trial (Wegovy) both documented gastrointestinal side effects in their participants. Burping and belching are not separately tracked as distinct side effects in official trial data; they fall under the broader category of "gastrointestinal disorders" or "nausea and vomiting."
What we know from clinical experience: digestive symptoms including gas and burping typically appear within the first 2–4 weeks of starting either medication and often improve as your body adapts, usually within 4–12 weeks. However, some people experience persistent mild burping throughout treatment. If you experience severe or worsening digestive symptoms, contact your GP — they may adjust your dose or suggest strategies to manage symptoms, such as eating smaller meals, slowing your eating pace, and staying hydrated.
Both Mounjaro and Wegovy require a prescription following a clinical assessment. The choice between them depends on your individual health profile, any pre-existing digestive conditions, BMI, and weight-related health conditions. Your prescriber will assess your suitability for each medication based on factors including your medical history, current medications, and personal preferences. Use our free BMI calculator above to check your current BMI and understand whether you may be eligible for either medication — then discuss options with your GP or a licensed 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.
Does Mounjaro cause more burping than Wegovy?
Clinical trial data does not directly compare burping between the two medications. Both cause gastrointestinal side effects including gas and belching. Individual responses vary significantly — some people experience more burping with one medication than the other. Your prescriber can help determine which is more suitable for you based on your health history.
How long does burping from GLP-1 injections last?
Burping and digestive symptoms typically begin within 2–4 weeks of starting treatment and often improve within 4–12 weeks as your body adapts. Some people experience persistent mild symptoms throughout treatment. Eating smaller meals, eating slowly, and staying hydrated may help reduce symptoms.
Can I switch from Mounjaro to Wegovy if I experience burping?
Any switch between medications must be managed by your prescriber. Do not stop or switch medications without medical guidance. If burping is severe or affecting your quality of life, speak to your GP — they may adjust your dose, suggest symptom management strategies, or discuss alternative options.
Are Mounjaro and Wegovy available on the NHS for burping side effects?
Mounjaro and Wegovy are prescribed for weight management in eligible UK adults, not to treat burping. Burping is a potential side effect, not a reason for prescription. Both are available through NHS specialist tier 3 weight management services (where available) or through private online prescribing following a clinical assessment.
What should I do if burping is severe when taking Mounjaro or Wegovy?
Contact your GP or prescriber immediately. Severe or persistent digestive symptoms may require dose adjustment, switching medications, or temporary discontinuation. Never adjust your dose yourself. Your prescriber can advise on managing symptoms and whether continuing treatment is appropriate for you.
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