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
Does Mounjaro Give You Wind — Comparison with Wegovy
Yes, wind and bloating are common side effects of Mounjaro, particularly in the first few weeks of treatment. Both Mounjaro (tirzepatide) and Wegovy (semaglutide) can cause gastrointestinal side effects including wind, bloating, and constipation or diarrhoea. The difference lies in their mechanisms: Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy is a GLP-1 agonist only. This page compares how these medications affect digestion and helps you understand what to expect if you're considering prescription weight loss treatment in the UK.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Mounjaro, Wegovy, and Gastrointestinal Side Effects — Clinical Evidence
Wind and bloating are classified as very common side effects of both Mounjaro and Wegovy, meaning they may affect more than 1 in 10 people taking these medications. In the SURMOUNT clinical trials for Mounjaro, gastrointestinal symptoms including nausea, constipation, diarrhoea, and stomach discomfort were reported by the majority of participants, particularly during the initial dose titration phase.
Wegovy, approved across the UK as a once-weekly GLP-1 injection, shows a similar side-effect profile. The STEP trials demonstrated comparable rates of gastrointestinal disturbance. Key differences emerge from their mechanisms: Mounjaro's dual GIP+GLP-1 action may affect gastric emptying differently than Wegovy's single GLP-1 mechanism, though individual responses vary considerably.
- Mounjaro KwikPen doses: Wind and bloating typically improve as your body adjusts, often reducing by weeks 8–12
- Wegovy dose titration: Slower dose escalation may reduce initial gastrointestinal symptoms
- Tirzepatide mechanism: The dual-action approach activates both GIP and GLP-1 pathways, which may initially cause more digestive changes
Both require a UK prescription and clinical assessment before starting. Your prescriber will discuss expected side effects and strategies to manage them.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Individual Suitability — Which Medication May Be Right for You
The choice between Mounjaro and Wegovy depends on your individual health profile, not on wind or bloating alone. A UK-licensed prescriber will assess your medical history, current medications, BMI, and any weight-related health conditions before recommending either medication.
Both medications are prescription-only and available through NHS specialist weight management services or private online prescribing with clinical assessment. If gastrointestinal symptoms are a concern, discuss this with your prescriber: strategies such as slower dose escalation, dietary adjustments, or timing of meals can help manage bloating and wind.
- NICE and NHS guidance: Both medications are approved for adults with BMI ≥30 or ≥27 with weight-related conditions
- South Asian, Chinese, Black African, or Black Caribbean adults: Lower BMI thresholds may apply due to higher metabolic risk at lower weights
- Mounjaro vs Wegovy eligibility: No significant difference — both require the same eligibility criteria and clinical assessment
Use our free GLP-1 weight loss calculator to understand potential outcomes, and our BMI calculator to check your current eligibility for prescription weight loss treatment.
- 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 wind than Wegovy?
Clinical trial data shows both medications cause similar rates of wind and bloating as very common side effects. Individual responses vary based on genetics, diet, and dosing schedule. Mounjaro's dual mechanism (GIP+GLP-1) may affect some people differently than Wegovy's single GLP-1 mechanism, but there is no evidence that one consistently causes more wind than the other. Your GP or prescriber can advise based on your personal health profile.
How long does wind and bloating last on Mounjaro?
Gastrointestinal side effects, including wind, typically peak in the first 2–4 weeks and often improve significantly by weeks 8–12 as your body adjusts. Slower dose titration with the Mounjaro KwikPen can help reduce initial symptoms. If symptoms persist beyond 12 weeks, inform your prescriber — dietary changes or dose adjustments may help.
What can I do to reduce bloating on Mounjaro or Wegovy?
Eat smaller, more frequent meals; avoid high-fat and high-fibre foods initially; stay hydrated; and take gentle exercise like walking. Some people find that eating slowly and chewing thoroughly reduces wind. Keep a food diary to identify trigger foods. Your prescriber or a registered dietitian can provide personalised advice. Both medications slow gastric emptying, so dietary adjustments are particularly important during dose titration.
Are wind and bloating reasons to stop Mounjaro or Wegovy?
Wind and bloating alone are not typically reasons to stop treatment — they usually improve over time. However, if you experience severe abdominal pain, persistent vomiting, or signs of pancreatitis (pain spreading to your back), seek urgent medical attention. Always discuss side effects with your prescriber rather than stopping medication without guidance. They may adjust your dose, timing, or dietary approach.
Can I switch from Mounjaro to Wegovy if I get wind?
Switching between medications is a prescriber decision and not typically necessary just because of wind or bloating, as both medications cause similar gastrointestinal side effects. Instead, discuss symptom management strategies with your GP or prescriber. If wind persists despite dose adjustments and dietary changes, your prescriber may explore other options — but the issue is usually temporary and manageable.
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.