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 Itching vs Wegovy — What's the Difference?
Itching (pruritus) is reported as a possible side effect with both Mounjaro and Wegovy, though it is not listed as a common side effect with either medication. When comparing these two prescription weight management injections, understanding how side effects differ between them can help you and your GP make an informed decision. Both are once-weekly GLP-1 medications licenced in the UK, but they work slightly differently. Our free GLP-1 weight loss calculator can help you explore potential outcomes with each option, and your prescriber will assess which is most suitable for your individual health profile.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 and Wegovy Differ — Mechanism and Clinical Data
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist—meaning it activates two hormone pathways, not just one. Wegovy (semaglutide) is a GLP-1-only agonist. This mechanism difference may influence how each medication is tolerated, though itching specifically is rare with both.
- In the SURMOUNT-1 clinical trial, itching was not reported as a very common or common side effect of tirzepatide (Mounjaro)
- In the STEP-1 clinical trial, itching was similarly not a prominent side effect of semaglutide (Wegovy)
- Very common side effects with both include nausea, diarrhoea, vomiting, and constipation
- Injection site reactions (redness, bruising, pain at the injection site) are more frequently reported than generalised itching
Individual tolerance varies significantly—what one person experiences may differ from another. Any skin changes or unusual itching should be reported to your GP or prescriber promptly.
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.
Which Medication Might Suit You — Individual Assessment
Neither Mounjaro nor Wegovy is inherently "better" for itching—both are prescription-only medicines that require clinical assessment before prescription. Your GP or prescriber will consider your medical history, other medications, weight loss goals, and any previous medication sensitivities when recommending one over the other.
If you experience itching during treatment with either medication, do not stop taking it without consulting your prescriber. Itching can sometimes be managed by adjusting injection sites, ensuring proper skin hygiene, or other measures. Your prescriber may also investigate whether itching is related to the injection itself or another cause entirely. Use our free BMI calculator to track your baseline health metrics and monitor progress once you begin 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.
Is itching a common side effect of Mounjaro?
Itching is not listed as a very common or common side effect of Mounjaro in clinical trials. The most frequently reported side effects are nausea, diarrhoea, vomiting, and constipation. If you experience itching, mention it to your GP or prescriber to rule out other causes.
Is itching more common with Wegovy than Mounjaro?
Itching is not a prominent side effect with either medication based on clinical trial data. Both are well-tolerated in terms of skin reactions. Individual experiences vary, so your prescriber will monitor you for any unusual symptoms during treatment.
What should I do if I develop itching while taking Mounjaro or Wegovy?
Report any new itching to your prescriber. Do not stop taking your medication without guidance. Your prescriber may investigate other causes, suggest changing injection sites, or adjust your treatment plan. Itching can sometimes be related to the injection technique or injection site hygiene rather than the medication itself.
How do I decide between Mounjaro and Wegovy if I'm worried about side effects?
Your GP or prescriber will assess your individual health profile, medical history, and any previous medication sensitivities. Neither medication is risk-free, but both are licenced and monitored in the UK. Discuss your concerns openly with your prescriber—they can help you weigh the benefits against potential side effects for your situation.
Can I switch from Mounjaro to Wegovy if I experience itching?
Any switch between medications must be managed by your prescriber. If itching occurs, your prescriber will first investigate the cause and may try adjusting your injection technique or site before considering a switch. Switching medications has its own considerations, so this decision requires professional guidance.
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.