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 — What You Need To Know
If you have psoriasis and are considering Mounjaro (tirzepatide) for weight management, it's important to understand how this GLP-1 and GIP receptor agonist might interact with your skin condition. Whilst Mounjaro is not known to cause psoriasis, some people with existing psoriasis have reported skin flares after starting the medication. This guide explains what the evidence shows, what your GP should assess before prescribing, and how to monitor your skin health whilst using this NHS-approved weight management treatment.
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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, Psoriasis, And Immune Response — What The Evidence Shows
Mounjaro (tirzepatide) works as a dual GIP and GLP-1 receptor agonist, supporting weight loss through appetite regulation and improved metabolic control. However, some clinical reports suggest that GLP-1 medications may occasionally trigger or worsen inflammatory skin conditions, including psoriasis, in certain individuals. This is not a common side effect listed in the official product information, but it has been documented in patient reports and clinical observations.
The mechanism is thought to relate to how GLP-1 receptor agonists affect immune function and inflammation in the body. Psoriasis is an autoimmune condition where the immune system attacks skin cells, causing red, scaly patches. If Mounjaro influences immune regulation, it could theoretically contribute to flares in susceptible individuals. However, this remains uncommon, and many people with psoriasis use GLP-1 medications without issues. Your GP or dermatologist should assess your individual risk before you start treatment.
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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.
What To Discuss With Your GP Before Starting Mounjaro
Before beginning Mounjaro, inform your GP or prescriber that you have psoriasis. This is essential information for your clinical assessment. Your healthcare team will review whether the benefits of weight loss—which itself often improves skin health through reduced inflammation and joint stress—outweigh any potential risk of psoriasis flares. They may also discuss your psoriasis severity, current treatments (including biologics), and whether closer monitoring is appropriate during the first few weeks of Mounjaro use.
If you're currently taking biologic medications for psoriasis, your GP needs to know this too, as interactions between Mounjaro and immunosuppressive treatments require careful consideration. Once you start Mounjaro, report any changes to your skin promptly—increased redness, scaling, itching, or new plaques—to your GP so adjustments can be made if needed.
NHS Access To Mounjaro And Managing Psoriasis Alongside TreatmentIn the UK, Mounjaro is available through NHS tier 3 specialist weight management services, though access varies significantly by region and waiting lists can be lengthy. Private prescribing is also available following an online clinical assessment with a UK-licensed prescriber. Regardless of access route, your psoriasis history must be disclosed and reviewed before treatment begins. Some NHS dermatology services can also provide liaison advice to weight management teams if your psoriasis is complex or severe.
Weight loss itself often improves psoriasis outcomes due to reduced systemic inflammation, joint stress, and improved metabolic markers. For many people with both obesity and psoriasis, the overall health benefits of weight management—achieved with Mounjaro alongside a reduced-calorie diet and increased physical activity—may be significant. However, individual responses vary. Use our free BMI calculator to understand your starting point, and our GLP-1 weight loss calculator to project potential outcomes with tirzepatide therapy.
- 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 if I don't already have it?
Mounjaro is not known to cause psoriasis in people without pre-existing skin conditions. However, it may occasionally trigger flares in people who already have psoriasis. This is uncommon and not listed as a standard side effect, but it has been reported by some patients. Your GP can assess your individual risk during consultation.
Will starting Mounjaro definitely make my psoriasis worse?
No. Many people with psoriasis use GLP-1 medications like Mounjaro without experiencing worsening of their skin condition. Some even find their psoriasis improves due to weight loss and reduced inflammation. Individual responses vary significantly, which is why pre-treatment discussion with your GP and dermatologist is important.
What should I monitor if I have psoriasis and start Mounjaro?
Monitor your skin closely during the first 4–8 weeks after starting Mounjaro. Report any new or worsening red patches, scaling, itching, or plaques to your GP promptly. Keep a simple log of skin changes alongside your weight loss progress using our free progress tracker. This helps your healthcare team assess whether any adjustments to your treatment are needed.
Can I take Mounjaro if I'm on biologic psoriasis medications?
This requires careful assessment by your GP or dermatologist. Biologic psoriasis treatments suppress immune function, and combining them with Mounjaro needs professional review. Your prescriber must know about all current medications, including biologics like secukinumab or adalimumab, before approving Mounjaro treatment.
Will weight loss from Mounjaro improve my psoriasis?
For many people, yes. Weight loss and improved metabolic health often reduce psoriasis severity because excess weight drives systemic inflammation. However, results vary. Some patients experience significant improvement, whilst others see little change. This is another reason to discuss your psoriasis with your GP before starting, as they can set realistic expectations for your skin outcomes.
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.