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 Asthma — What You Need To Know
If you have asthma and are considering Mounjaro (tirzepatide) for weight management, it's important to understand how this GLP-1 and GIP receptor agonist may interact with your condition. Mounjaro is not known to directly cause or worsen asthma, but certain side effects — particularly nausea and stomach issues — may occasionally trigger asthma symptoms in sensitive individuals. Your GP or prescriber needs to know about your asthma before starting any weight loss medication. This guide explains what the NHS and clinical evidence tells us about using Mounjaro safely if you have asthma.
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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.
Mounjaro, Asthma, And Your Airways
Mounjaro (tirzepatide) works as a dual GIP and GLP-1 receptor agonist, helping regulate appetite and blood sugar control. Unlike some medications, tirzepatide is not listed as a contraindication for people with asthma, meaning it is not automatically unsafe. However, several factors warrant careful consideration:
- Nausea and reflux: Mounjaro commonly causes nausea, indigestion, and acid reflux (GORD) — conditions that can occasionally trigger asthma symptoms in susceptible individuals, particularly nocturnal asthma
- Stomach pain: Abdominal discomfort may indirectly affect breathing if severe
- Individual variation: Not everyone with asthma will experience asthma-related side effects from Mounjaro
- Prescriber assessment: Your prescriber must conduct a full medical history including asthma severity, control, and current medications before starting tirzepatide
A prescriber can assess whether Mounjaro is appropriate for your individual situation and may recommend additional monitoring or precautions if you have poorly controlled asthma.
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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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS Route And Asthma Considerations
If accessing Mounjaro through the NHS via a tier 3 specialist weight management service, the clinical team will review your full medical history, including your asthma. Inform your healthcare team immediately if:
- Your asthma is poorly controlled or you have frequent attacks
- You use a reliever inhaler more than twice per week
- You are on oral steroids for asthma management
- You have had asthma attacks triggered by gastrointestinal issues in the past
If your asthma is well-controlled with regular preventive medication (such as an inhaled corticosteroid and/or long-acting beta-agonist), Mounjaro may still be considered suitable. Your prescriber may recommend starting at the lowest dose (2.5 mg) and monitoring carefully during dose titration to spot any asthma-related changes. Report any increase in asthma symptoms or reliever use to your GP immediately.
- 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.
Can Mounjaro trigger asthma attacks?
Mounjaro itself does not directly trigger asthma. However, side effects like nausea, reflux, and stomach pain may occasionally worsen asthma in sensitive individuals. If you experience increased asthma symptoms after starting Mounjaro, contact your GP immediately.
Should I tell my prescriber I have asthma?
Yes, absolutely. Always inform any prescriber — whether NHS or private — about your asthma, current asthma control, and any asthma medications you take. This allows them to assess whether Mounjaro is safe for you and recommend monitoring if needed.
Will acid reflux from Mounjaro affect my asthma?
Acid reflux is a known trigger for asthma symptoms, especially at night. Mounjaro commonly causes reflux. If you develop reflux-related asthma symptoms, discuss this with your GP. They may suggest reflux management or review your Mounjaro dose.
Can I use Mounjaro if my asthma is well-controlled?
Yes, well-controlled asthma (managed with regular preventive inhalers) is not an automatic contraindication. Your prescriber will assess your individual risk. However, monitoring during dose titration is important to ensure your asthma remains stable.
What should I do if my asthma worsens on Mounjaro?
Stop any new behaviours that might worsen asthma, and contact your GP immediately. Your prescriber may pause tirzepatide, reduce your dose, or manage reflux-related symptoms with additional medication. Never ignore changes in asthma control.
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.