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
Can Mounjaro Cause Hair Loss?
Hair loss (alopecia) is listed as a common side effect of Mounjaro in the UK, affecting up to 1 in 10 people taking this weekly weight loss injection. However, hair loss with Mounjaro is not automatic — most users do not experience it, and when it does occur, it is often temporary. Understanding the link between tirzepatide and hair loss, what causes it, and how to access this prescription-only medication through the NHS or private clinics with full support is essential for making an informed decision about weight management treatment.
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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.
Hair Loss as a Mounjaro Side Effect
Hair loss is classified as a common side effect of Mounjaro (tirzepatide), occurring in approximately 1 in 10 users during clinical trials. This typically manifests as increased shedding rather than visible baldness or bald patches. The hair loss is believed to be related to gradual weight management itself rather than the medication directly — a phenomenon called telogen effluvium, where hair prematurely enters its resting and shedding phase due to metabolic stress.
The timing is important: if hair loss occurs, it usually begins 2–3 months after starting the weekly weight loss injection and may continue for several months. Hair typically regrows once weight stabilises. Other common side effects alongside hair loss include nausea, diarrhoea, and constipation. Hair loss can also be worsened by nutrient deficiencies if calorie intake is too restricted, which is why balanced nutrition alongside reduced-calorie diet is recommended. Your prescriber should assess your individual risk factors before starting this prescription medication.
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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.
Accessing Mounjaro in the UK: Cost and Routes
NHS access: Mounjaro is available through specialist tier 3/4 weight management services following referral from your GP, though availability and waiting times vary significantly by region. Private access: This weekly injection is available through private GPhC-registered prescribers and pharmacies following an online clinical assessment, with costs typically ranging from £129–£320 per month depending on dose. The KwikPen device requires refrigeration (2–8°C when unopened, up to 30 days at room temperature after first use). Use our GLP-1 weight loss calculator to explore projected outcomes at different doses, and our BMI calculator to understand your starting point before discussing options with a prescriber or GP.
- 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.
Does everyone taking Mounjaro experience hair loss?
No. Hair loss affects approximately 1 in 10 people — most users do not experience noticeable shedding. When it does occur, it is often mild and temporary, typically reversing once weight stabilises. Severity varies between individuals based on genetics, nutrition, and the speed of weight loss.
Why does Mounjaro cause hair loss?
Hair loss is linked to telogen effluvium, a condition triggered by gradual weight management and metabolic stress rather than tirzepatide itself. When the body loses weight quickly, hair follicles prematurely enter their resting phase and shed. This is a temporary response and regrowth typically follows as weight stabilises.
How long does Mounjaro-related hair loss last?
If it occurs, hair loss usually begins 2–3 months after starting treatment and may continue for several months. Regrowth typically begins once your weight loss rate slows and stabilises. Most users report full recovery within 6–12 months of stopping shedding.
Can I reduce hair loss risk while taking Mounjaro?
Ensure adequate protein intake, balanced nutrition with sufficient iron and zinc, and avoid extremely restrictive diets alongside your reduced-calorie meal plan. Stay well hydrated and discuss any concerns with your prescriber. Gradual, steady weight loss (0.5–1 kg per week) rather than rapid loss may reduce telogen effluvium risk.
How do I get Mounjaro prescribed in the UK?
Via NHS specialist weight management services (referral from GP, variable waiting times and regional availability) or private prescription through an online clinical assessment with a UK-licensed prescriber. Costs, eligibility criteria, and access routes differ — your GP can discuss NHS options, or you can explore private routes directly with registered pharmacies.
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.