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 Loss: What You Need to Know
Hair loss (alopecia) is a known side effect reported by some people taking Mounjaro (tirzepatide) in the UK. While not everyone experiences it, understanding this potential side effect is important when considering prescription weight loss treatment. This guide covers what the evidence shows, why it happens, and what you can do if you're concerned. Always discuss any side effects with your GP or prescriber.
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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 Loss with Mounjaro — What the Evidence Shows
Hair loss is listed as a common side effect of Mounjaro in UK prescribing information, meaning it may affect up to 1 in 10 people taking the medication. In clinical trials, alopecia was reported during the SURMOUNT-1 study, though it was not the most frequently reported side effect compared to nausea, diarrhoea, and constipation.
- Timing: Hair loss typically begins after several weeks of treatment and may continue for a few months
- Reversibility: In most cases, hair growth normalises after stopping Mounjaro or as your body adjusts to the medication
- Severity: Most reported cases are mild to moderate, not total hair loss
- Risk factors: People with existing hair loss conditions, nutritional deficiencies, or significant gradual weight management may be at higher risk
Hair loss during gradual weight management is partly explained by telogen effluvium — a temporary condition where hair follicles shift into a resting phase due to metabolic stress. This is separate from male or female pattern baldness and is usually reversible.
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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 Loss on Mounjaro — Practical Steps
If you experience hair loss while taking Mounjaro, discuss it with your GP or prescriber — they can assess whether it's medication-related or due to other factors like nutritional deficiency. Practical steps include: ensuring adequate protein intake (hair is made of keratin, a protein), maintaining sufficient micronutrients like iron, zinc, and B vitamins, and managing stress where possible. Some people find biotin supplements helpful, though evidence is mixed. Consider using a gentle hair care routine and avoid tight hairstyles that stress follicles. Your prescriber may adjust your dose, slow your titration schedule, or recommend a temporary pause if hair loss is severe. Use our free BMI calculator to monitor your overall health progress alongside any side effect concerns.
- 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 common with Mounjaro in the UK?
Hair loss is listed as a common side effect, affecting up to 1 in 10 people. However, not everyone experiences it, and when it does occur, it's usually mild to moderate and often reversible after stopping treatment or as your body adjusts.
Why does Mounjaro cause hair loss?
gradual weight management can trigger telogen effluvium, where hair follicles shift into a resting phase due to metabolic stress. This is a temporary condition unrelated to male or female pattern baldness and typically reverses over time.
Can I prevent hair loss while taking Mounjaro?
Ensure adequate protein intake, maintain sufficient iron and zinc levels, and use a gentle hair care routine. Discuss your concerns with your GP — they may recommend nutritional support or adjust your treatment schedule if needed.
Is hair loss from Mounjaro permanent?
No. In most cases, hair loss is temporary and reversible. Hair growth typically normalises after stopping Mounjaro or as your body adjusts. Consult your prescriber if you're concerned about the timing or severity.
Should I stop taking Mounjaro if my hair falls out?
Do not stop without speaking to your prescriber. They can assess whether the hair loss is medication-related, recommend management strategies, or adjust your treatment plan. Sometimes slowing your dose increase helps.
Ready to take control of your weight loss journey?
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