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 Hair Thinning — A UK Health Guide
Hair thinning (alopecia) is listed as a possible side effect of Mounjaro (tirzepatide), though it's not one of the most common effects. If you're considering Mounjaro as part of weight management or are already taking it and noticing hair changes, it's worth understanding what the evidence shows, why it might happen, and what steps you can take. This guide explains the facts about Mounjaro and hair loss, based on UK clinical data and NHS guidance.
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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.
Hair Thinning and Mounjaro — What the Evidence Shows
In clinical trials, hair loss (alopecia) was reported as a common side effect affecting up to 1 in 10 people taking Mounjaro. However, this includes all types of hair shedding and thinning — severe hair loss requiring treatment is less frequent. Hair thinning can occur because gradual weight management itself can trigger telogen effluvium, a temporary condition where hair enters the shedding phase more quickly than normal. Additionally, when the body is in a significant calorie deficit or experiencing nutritional changes, hair follicles may become stressed. Mounjaro works by reducing appetite and food intake, which — combined with dietary changes — creates the conditions for this type of hair shedding.
- Hair thinning reported in clinical trials at a similar rate to other GLP-1 medications like Wegovy (semaglutide)
- Telogen effluvium from gradual weight management typically reverses within 3–6 months of weight stabilising
- Severe permanent hair loss from Mounjaro alone is uncommon
- Nutritional deficiency during weight loss can worsen hair thinning — adequate protein and micronutrients matter
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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.
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Managing Hair Thinning While Taking Mounjaro
If you notice hair thinning while taking Mounjaro, inform your GP or the prescriber managing your treatment. This is important because hair changes can indicate nutritional gaps or warrant dose adjustment. Practical steps include: ensure adequate protein intake (aim for 1.2–1.6g per kg of body weight daily), take a multivitamin with iron, zinc, and B vitamins, avoid crash dieting beyond the appetite suppression Mounjaro provides, and be patient — most hair shedding from weight loss reverses naturally. You can track your progress with our free progress tracker to monitor weight loss and any patterns with side effects. Do not stop taking Mounjaro without consulting your prescriber, as sudden discontinuation may cause other complications.
- 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 a serious side effect of Mounjaro?
Hair thinning from Mounjaro is usually temporary and related to gradual weight management rather than the drug itself. Most people experience telogen effluvium, which reverses within 3–6 months. Severe permanent hair loss is uncommon. If you're concerned, discuss it with your GP.
How common is hair thinning with Mounjaro?
Hair loss was reported in up to 1 in 10 people in clinical trials, making it a "common" side effect. However, this includes all levels of shedding — noticeable but reversible thinning rather than complete baldness is typical.
Can I prevent hair thinning while taking Mounjaro?
Ensure adequate protein and micronutrients (iron, zinc, B vitamins) during weight loss. Avoid excessive calorie restriction beyond what Mounjaro naturally provides. Take a multivitamin if recommended by your prescriber. Hair health depends on overall nutrition.
How does Mounjaro compare to Wegovy for hair thinning?
Both Mounjaro and Wegovy are GLP-1-type medications and show similar rates of hair thinning in trials (around 1 in 10). The thinning is mainly from weight loss effects, not the specific drug. Individual experiences vary significantly.
Should I stop taking Mounjaro if my hair is thinning?
Do not stop without consulting your prescriber — they can assess whether the hair thinning is from Mounjaro or from the weight loss process itself, and whether continuing is right for you. Stopping suddenly may cause other complications.
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.