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, Asthma, and Weight Management in the UK
If you have asthma and are considering Mounjaro (tirzepatide) for weight management, it's important to understand how this prescription injection may interact with your respiratory health. Mounjaro is a dual GIP and GLP-1 receptor agonist that may help support weight loss alongside lifestyle changes. However, asthma requires careful consideration when starting any new medication. This guide explains what you need to know about Mounjaro for asthma sufferers in the UK, how it compares to alternatives like Wegovy, and why a clinical assessment from your GP is essential before treatment begins.
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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 Respiratory Considerations
Mounjaro (tirzepatide) is not known to directly cause asthma or worsen it in clinical trials, but people with asthma should inform their prescriber before starting treatment. GLP-1 and GIP receptor agonists work by activating natural hormone pathways that regulate appetite and blood sugar — they do not directly affect airways or lung function.
However, weight loss itself often improves asthma symptoms, as excess weight can restrict breathing and increase airway inflammation. Some Mounjaro side effects — particularly nausea and gastrointestinal symptoms — may feel uncomfortable if you have respiratory conditions, though they are typically mild and temporary.
If you take asthma medications (especially inhalers), Mounjaro may slow the absorption of oral medications taken at the same time. This is why timing and disclosure matter: tell your prescriber about all respiratory medications, including inhalers, steroid tablets, or nebulisers. Your prescriber may advise spacing doses apart or monitoring more closely. Use our free GLP-1 weight loss calculator to explore whether Mounjaro might suit your health goals, but always confirm suitability with a licensed prescriber.
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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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Mounjaro vs Wegovy for Adults with Asthma
Both Mounjaro and Wegovy are prescription-only weight management injections licensed in the UK, but they have different mechanisms. Mounjaro is a dual GIP and GLP-1 agonist (average weight loss ~15–21% in SURMOUNT trials), while Wegovy is a GLP-1 agonist only (average weight loss ~15% in STEP trials). Neither is specifically contraindicated in asthma, but individual suitability depends on your asthma severity, current medications, and overall health.
For asthma sufferers, the choice between them is not about one being "safer" — it's about which fits your health profile better. Your prescriber will assess this during clinical evaluation. Both require a UK prescription and clinical assessment. Weight loss with either medication may improve asthma control over time, as reducing excess weight often eases breathing. Track your progress with our free progress tracker once you and your prescriber decide on 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 make asthma worse?
Mounjaro is not known to directly worsen asthma in clinical trials. However, any new medication should be discussed with your GP or asthma specialist. Weight loss from Mounjaro may actually improve asthma symptoms, as excess weight restricts breathing. Always disclose your asthma diagnosis and current medications before starting treatment.
Can I take Mounjaro if I use an asthma inhaler?
Yes, but inform your prescriber beforehand. Mounjaro may slow absorption of some oral medications, though inhalers are typically less affected. Your prescriber may advise on timing or monitoring. Never stop asthma medication without medical guidance, as weight loss injections are supplements to, not replacements for, asthma management.
Is Wegovy safer than Mounjaro for asthma?
Neither is specifically safer for asthma — both are GLP-1-based medications with similar safety profiles in respiratory conditions. The choice depends on your individual health, other medications, and prescriber assessment. SURMOUNT and STEP clinical trials did not identify asthma as a limiting factor for either drug.
Will losing weight with Mounjaro help my asthma?
Possibly. Excess weight increases airway inflammation and restricts breathing, so weight loss often improves asthma control and reduces inhaler use. However, results vary. Work with both your weight management prescriber and asthma specialist to monitor improvements safely alongside any treatment.
What if my asthma is severe — can I still take Mounjaro?
Severe asthma requires specialist assessment. Contact your respiratory consultant or GP before considering Mounjaro. They will evaluate whether the medication's benefits outweigh any risks specific to your asthma severity, current treatments, and overall health. Clinical assessment is always required before prescription.
Ready to take control of your weight loss journey?
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