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
Mounjaro and Steroids — What You Need to Know
If you're taking steroids and considering Mounjaro (tirzepatide), it's important to understand how these medications may interact. Steroids can affect blood sugar levels and weight management, which is relevant when using a GLP-1 and GIP receptor agonist like Mounjaro. This guide explains the relationship between these medications, eligibility considerations, and what to discuss with your GP before starting treatment in the UK.
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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.
How Steroids Affect Weight Management and Mounjaro Use
Steroids and weight gain are closely linked. Corticosteroids (such as prednisolone or dexamethasone) commonly cause increased appetite, fluid retention, and fat redistribution, making weight management significantly more challenging. They also increase blood sugar levels, which is particularly important if you have type 2 diabetes or prediabetes.
When considering Mounjaro, your prescriber needs to know about any steroid use because:
- Steroids increase appetite; Mounjaro reduces it — creating opposing effects
- Steroids raise blood glucose; Mounjaro helps regulate it
- The combination may require careful monitoring and dose adjustment
- Long-term steroid use may affect the overall effectiveness of weight loss medication
If you're on steroids for a medical condition (such as rheumatoid arthritis, asthma, or autoimmune disease), your GP and prescriber must assess whether Mounjaro is appropriate and whether your steroid dose can be optimised. Never stop steroids without medical advice — this could be dangerous.
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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.
Eligibility and What to Tell Your Prescriber
When applying for a Mounjaro UK prescription, you must disclose all medications, including steroids. Your prescriber will assess whether treatment is clinically appropriate given your overall health.
For NHS access, referral to a specialist tier 3 weight management service is required; they will review your full medical history. For private prescription, an online clinical assessment will ask about steroid use, dosage, and indication.
Key points: You are not automatically ineligible for Mounjaro if taking steroids, but your case requires individual assessment. Your GP can help coordinate between your specialist (managing the steroid-requiring condition) and your weight management prescriber to ensure safe, effective 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.
Can I take Mounjaro while on long-term steroids?
Potentially, yes — but it requires careful assessment and monitoring by your prescriber. Steroids and Mounjaro work in opposite directions regarding appetite and blood sugar, so your prescriber needs to evaluate whether the combination is safe for your individual situation. Always disclose steroid use during your clinical assessment.
Will Mounjaro work if I'm taking steroids?
Steroids can reduce the effectiveness of weight loss medication by increasing appetite and causing metabolic changes. However, Mounjaro may still help. Your prescriber will assess whether it's worth trying and whether your steroid dose can be optimised. Results will vary based on the type and dose of steroid you're taking.
Do I need to stop steroids before starting Mounjaro?
No — never stop steroids without medical advice, as this could be dangerous depending on your condition. Instead, inform your prescriber about your steroid use during your clinical assessment. They may discuss whether your steroid regimen can be adjusted, but this decision must involve the doctor managing your underlying condition.
What steroids interact with Mounjaro?
All corticosteroids (prednisolone, dexamethasone, hydrocortisone, etc.) can affect weight and blood sugar. Your prescriber needs to know about any steroid use, regardless of type or dose. Even low-dose steroids can impact weight management, so transparency is essential during your assessment.
Should I mention steroid use when applying for Mounjaro online?
Yes, absolutely. Online clinical assessments ask about all medications for good reason. You must declare steroid use, including the type, dose, and reason you're taking it. Failing to disclose medications could result in an unsafe prescription or rejection of your application.
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.