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 — UK Health Information
If you have asthma and are considering Mounjaro (tirzepatide) for weight management, it's important to understand how this prescription-only medication may interact with your condition. Mounjaro is a dual GIP and GLP-1 receptor agonist that works by regulating appetite and blood sugar. While asthma itself is not listed as a contraindication, anyone with respiratory conditions should discuss their full medical history with their prescriber before starting treatment. Your GP or the prescriber conducting your clinical assessment must be aware of your asthma to ensure Mounjaro is safe and appropriate for you.
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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.
How Mounjaro Works and Respiratory Health
Mounjaro (tirzepatide) is a once-weekly injectable weight management medication licensed in the UK. It works by activating two natural hormone pathways — GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) — which help regulate appetite and food intake. The medication does not directly affect the lungs or airways, and there is no established mechanism by which tirzepatide would worsen asthma control in most patients.
However, weight loss itself can significantly improve asthma symptoms in people living with obesity. Excess weight increases mechanical pressure on the airways and lungs, and weight loss of even 5–10% can reduce asthma severity, decrease medication requirements, and improve exercise tolerance. This means Mounjaro may indirectly benefit your respiratory health through weight reduction. The GLP-1 component also has potential anti-inflammatory effects, though research in asthma specifically is ongoing.
Importantly, any medication changes or new asthma symptoms that emerge during Mounjaro treatment should be reported to your GP or asthma care team immediately.
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.
Important Considerations Before Starting Mounjaro
If you have asthma and wish to try Mounjaro, you must disclose your full respiratory health history to the prescriber during your clinical assessment. This includes: current asthma control level, medications you take (including inhalers and oral corticosteroids), how often you experience symptoms, and any recent hospital admissions or emergency treatment. Your prescriber may also need to know if you have other lung conditions or if your asthma is triggered by specific factors like exercise or allergies.
Some people report gastrointestinal side effects on Mounjaro — including nausea, vomiting, and constipation — which could theoretically affect posture or abdominal pressure during an asthma attack, though this is not a documented clinical concern. As with any new medication, monitor your asthma closely and keep your rescue inhaler accessible. If asthma control worsens or you experience new symptoms, contact your GP immediately. Your asthma and weight management should be managed collaboratively between your GP and weight management prescriber.
Using Our Free Tools to Support Your JourneyManaging weight whilst living with asthma requires a personalised approach. Our free BMI calculator above can help you understand your current weight classification and set realistic health targets with your GP. If you're interested in exploring how much weight Mounjaro might help you lose, our GLP-1 weight loss calculator can provide a projection based on published clinical trial data — though individual results vary considerably. Many people find our progress tracker helpful for logging both weight changes and asthma control improvements, allowing you to spot correlations between weight loss and breathing improvements. Always work with your prescriber and asthma care team — they can advise whether Mounjaro is suitable for your specific situation and monitor your progress safely throughout 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.
Will Mounjaro make my asthma worse?
There is no direct mechanism by which Mounjaro worsens asthma. However, any new medication can cause unexpected side effects in individual patients. Weight loss from Mounjaro may actually improve asthma control. Always inform your prescriber of your asthma history before starting treatment, and report any new respiratory symptoms to your GP immediately.
Can I take Mounjaro if I'm on asthma inhalers and oral medications?
Mounjaro can interact with the absorption of some oral medications due to its effect on gastric emptying. If you take corticosteroid tablets, antihistamines, or other regular medications, your prescriber must know. Inhalers (rescue or preventive) do not have direct interactions with Mounjaro, but your GP should review all medications during assessment.
Does weight loss from Mounjaro help asthma?
Yes — evidence shows that even 5–clinically studied weight loss reduces asthma severity, improves control, and can lower medication requirements in people living with obesity. Weight loss reduces mechanical pressure on airways and may reduce systemic inflammation, both beneficial for asthma management.
What should I tell my prescriber about my asthma?
Disclose your current asthma control level, frequency of symptoms or rescue inhaler use, all asthma medications, any recent hospital admissions or emergency treatment, and any triggers (exercise, allergies, etc.). Also mention if you take oral corticosteroids regularly, as this affects medication interactions.
Is Mounjaro available on the NHS for people with asthma and obesity?
NHS access to Mounjaro (tirzepatide) depends on your BMI and any weight-related health conditions, through specialist tier 3 weight management services. Asthma can be a relevant health condition for eligibility assessment. Ask your GP for a referral to your local specialist weight management service to explore options.
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.