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 Psoriasis — Important Health Information
If you have psoriasis and are considering Mounjaro for weight management, it's natural to wonder whether this medication might affect your skin health. Mounjaro (tirzepatide) is a GLP-1 and GIP receptor agonist prescribed in the UK for weight management in eligible adults. While psoriasis is not a known side effect in clinical trials, anyone with existing skin conditions should discuss their medical history with their GP or prescriber before starting any new medication. This guide covers what we know about Mounjaro, psoriasis risk, and how to access weight management support safely 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.
What the Evidence Shows About Mounjaro and Skin Health
In the SURMOUNT clinical trials that led to Mounjaro's approval, psoriasis was not reported as a common or serious side effect. The most frequently reported side effects were gastrointestinal, including nausea, diarrhoea, vomiting, and constipation. However, individual responses to medications vary considerably.
Some patients taking GLP-1 medications (including semaglutide-based Wegovy) have reported skin changes or flare-ups in existing skin conditions, though these are not formally listed as known side effects. If you have a history of psoriasis or other autoimmune skin conditions, your prescriber needs to know this before you start Mounjaro. Weight loss itself often improves psoriasis symptoms in overweight individuals, so the net effect may actually be positive for your skin health. The safest approach is full transparency with your GP about your complete medical history, including any skin conditions, before beginning treatment with tirzepatide.
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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 vs Private Access and What to Discuss With Your Prescriber
In the UK, Mounjaro is available through two routes: NHS specialist weight management services (tier 3/4) following GP referral, or private online prescribing following a clinical assessment with a UK-licensed prescriber. Either route requires a consultation where your full medical history is reviewed.
Before starting Mounjaro, you must inform your prescriber about psoriasis or any other skin conditions, autoimmune disorders, or history of thyroid problems. They will assess whether tirzepatide is suitable for you personally. You can also use our free BMI calculator above to check your current BMI and discuss your eligibility with your GP. If you're managing weight alongside psoriasis, ask your prescriber about the dose titration schedule and any interactions with your current skin treatments, as some medications may interact with tirzepatide.
- 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 cause psoriasis?
Psoriasis is not listed as a known side effect of Mounjaro in clinical trials. The most common side effects are gastrointestinal. However, if you have existing psoriasis, inform your prescriber before starting treatment so they can monitor you and assess individual risk.
Will Mounjaro make my psoriasis worse?
There is no strong evidence that Mounjaro worsens psoriasis. In fact, weight loss often improves psoriasis symptoms in overweight individuals. Each person's response is different—discuss your specific situation with your GP or the prescriber conducting your clinical assessment.
Can I take Mounjaro if I have psoriasis?
Yes, many people with psoriasis take Mounjaro safely. Your prescriber will review your full medical history and assess whether it's appropriate for you. Full transparency about your skin condition is essential so they can monitor you properly during treatment.
How do I access Mounjaro in the UK if I have psoriasis?
Through NHS specialist services (via GP referral) or private online prescribing (following clinical assessment). Either way, you'll have a consultation where you disclose your psoriasis history. Your prescriber can then decide if Mounjaro is suitable.
Should I stop my psoriasis treatment when starting Mounjaro?
No—do not stop any existing medications without medical advice. Tell your prescriber about all current treatments, including psoriasis medications, when you're assessed for Mounjaro. They will advise on any potential interactions or adjustments needed.
Ready to take control of your weight loss journey?
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