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
Is Hair Loss A Side Effect Of Mounjaro?
Yes, hair loss (alopecia) is a known side effect of Mounjaro (tirzepatide), though it's not one of the most common ones. It's listed as a common side effect that may affect up to 1 in 10 people taking this weight loss injection. Hair loss can occur at any dose level during treatment, and it's important to understand when it might happen, how long it typically lasts, and when you should contact your GP if you're concerned.
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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 On Mounjaro — What The Evidence Shows
Hair loss on Mounjaro was observed in clinical trials, though it's less frequently reported than nausea or stomach-related side effects. The mechanism isn't entirely clear, but gradual weight management itself can trigger telogen effluvium — a temporary condition where hair enters the shedding phase earlier than normal. This is not permanent baldness, but increased shedding over several weeks.
- Occurs in approximately 1 in 10 people taking Mounjaro
- Can happen at any dose during the dose titration phase or maintenance
- Usually appears 2–3 months into treatment
- Typically resolves within 3–6 months after stopping or stabilising on the medication
- More common in people experiencing significant or gradual weight management
If you're prescribed this weekly weight loss injection through your GP or a licensed prescriber, discuss hair loss risk beforehand. Use our free GLP-1 weight loss calculator to understand what to expect with your potential weight loss trajectory — this may help contextualise hair loss risk with your individual outcomes.
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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.
When To Contact Your GP About Hair Loss
If you notice unusual hair loss, patchy baldness, or scalp inflammation while taking Mounjaro, inform your prescriber. Most hair loss related to weight loss medications is temporary and self-limiting, but your GP can rule out other causes like thyroid problems or nutritional deficiencies — both of which can be affected by gradual weight management.
- Sudden or excessive shedding beyond normal daily loss
- Visible bald patches on your scalp
- Scalp pain, redness, or inflammation
- Hair loss continuing beyond 6 months after stabilising treatment
Your prescriber may recommend nutritional support, biotin supplements, or temporary dose adjustment. Never stop taking Mounjaro without medical guidance — discuss any concerns at your next review appointment.
- 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 hair loss from Mounjaro permanent?
No. Hair loss from Mounjaro-related gradual weight management is usually temporary (telogen effluvium), not permanent. Most people see regrowth within 3–6 months after stopping the medication or once weight stabilises. If hair loss continues beyond this timeframe, your GP can investigate other underlying causes.
How common is hair loss with Mounjaro?
Hair loss is listed as a common side effect affecting up to 1 in 10 people taking Mounjaro. However, it's less frequently reported than nausea or constipation. Not everyone experiences it, and severity varies widely between individuals.
Can I prevent hair loss while taking Mounjaro?
There's no assured prevention, but maintaining adequate protein intake, vitamins (especially iron, zinc, and B vitamins), and staying hydrated may support hair health during weight loss. Discuss nutritional supplementation with your GP or a registered dietitian before starting Mounjaro.
Does hair loss happen at every Mounjaro dose?
Hair loss can occur at any dose during the dose titration process or at maintenance doses. It's more likely if you're experiencing gradual weight management. Some people notice it only after reaching higher doses when weight loss accelerates.
Should I stop taking Mounjaro if I experience hair loss?
No — do not stop taking Mounjaro without medical guidance. Instead, contact your prescriber to discuss the hair loss. They can assess whether it's related to the medication, adjust your dose, or recommend supportive nutritional strategies. Hair loss alone is not a reason to discontinue treatment, but your GP should monitor it.
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.