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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Hair Loss on Mounjaro — Causes and What You Can Do
Hair loss is a recognised side effect of Mounjaro (tirzepatide), though it does not affect everyone. Many people taking this prescription-only weight management injection report noticing increased hair shedding, especially in the first few months of treatment. Understanding why this happens and what steps you can take may help you manage it more effectively. This guide explains the causes, timeline, and practical strategies to minimise hair loss whilst on Mounjaro treatment in the UK.
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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.
Why Does Mounjaro Cause Hair Loss?
Hair loss on Mounjaro is typically linked to gradual weight management and nutritional changes rather than the tirzepatide itself. When your body loses weight quickly, it can trigger a type of hair loss called telogen effluvium — a temporary condition where hair follicles prematurely enter a resting phase before shedding. This is more common with weight loss than with the medication directly.
Several factors contribute to this:
- Calorie deficit: gradual weight management from a reduced-calorie diet can shock the hair growth cycle
- Nutritional deficiency: Reduced food intake may mean less protein, iron, zinc, and B vitamins — all crucial for healthy hair
- Stress and metabolic change: Your body's response to significant weight changes can trigger temporary shedding
Clinical trials and real-world data show that Mounjaro-related hair loss is usually temporary and resolves once weight stabilises and nutrition improves. Most people see regrowth within 3–6 months of the shedding stopping.
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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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How to Minimise Hair Loss While on Mounjaro
Prioritise protein intake: Aim for at least 1.2–1.6g of protein per kg of body weight daily — hair is primarily made of protein. Include eggs, fish, poultry, legumes, and Greek yoghurt.
Take key supplements: Consider discussing with your GP whether you need iron, zinc, vitamin B12, and biotin supplements — deficiencies are common during weight loss and directly impact hair health.
Eat nutrient-dense foods: Focus on leafy greens, nuts, seeds, and whole grains rather than empty calories. A balanced diet slows weight loss naturally and preserves hair health.
Stay hydrated: Dehydration can worsen hair shedding. Aim for 6–8 glasses of water daily.
Gentle hair care: Use a soft brush, avoid tight hairstyles, and limit heat styling whilst shedding is active. Consider a silk pillowcase to reduce friction.
- 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 permanent side effect of Mounjaro?
No. Hair loss on Mounjaro is almost always temporary and linked to gradual weight management rather than the medication itself. Most people experience regrowth within 3–6 months once weight stabilises and nutrition improves. If hair loss persists beyond 6 months or is severe, consult your GP.
When does hair loss start on Mounjaro?
Telogen effluvium typically appears 2–3 months after starting Mounjaro or increasing doses, as hair follicles shift into the resting phase. Peak shedding usually occurs around months 2–4 of treatment, then gradually improves as weight loss slows and nutrient absorption stabilises.
Can I prevent hair loss on Mounjaro?
You cannot eliminate it entirely if you are losing weight rapidly, but you can minimise it. Prioritise protein (1.2–1.6g per kg daily), ensure adequate iron and zinc intake, maintain a balanced diet, stay hydrated, and discuss supplements with your GP. Slower, steadier weight loss also helps preserve hair health.
Should I stop taking Mounjaro if my hair is falling out?
No — do not stop without consulting your GP. Hair loss is usually temporary and reversible. Stopping Mounjaro may halt weight loss progress without necessarily stopping shedding. Instead, discuss with your GP or prescriber about optimising your nutrition or adjusting your approach. Your GP can also rule out other causes of hair loss.
Is hair loss on Mounjaro the same as on Wegovy or other weight loss injections?
Yes. Hair loss is a recognised side effect of most GLP-1 and GIP/GLP-1 medications (Mounjaro, Wegovy, Saxenda) because it is linked to gradual weight management, not the specific medication. The cause, timeline, and management strategies are similar across all weight loss injections. Your prescriber can advise on your individual situation.
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.