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
Hair Loss on Mounjaro — What Causes It and What You Can Do
Hair loss is a reported side effect of Mounjaro (tirzepatide) that affects some users, though it's not assured to happen to everyone. Hair thinning typically appears within the first few weeks of starting treatment, particularly during the dose titration phase, and is often temporary. Understanding why it happens and what steps you can take may help you manage this side effect effectively whilst benefiting from the medication's weight management support.
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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 on Mounjaro vs Wegovy — Clinical Context
Hair loss is listed as a common side effect of Mounjaro in UK clinical data, affecting up to 1 in 10 people. In the SURMOUNT-1 clinical trial, alopecia (hair loss) was reported during treatment with tirzepatide. Wegovy (semaglutide), a GLP-1 agonist, also reports hair loss as a common side effect, though some users report it less frequently than with Mounjaro's dual GIP and GLP-1 mechanism. The difference may relate to how each medication affects nutrient absorption and metabolism. Both medications can slow gastric emptying, potentially affecting how your body absorbs vitamins and minerals essential for hair health. Hair loss on weight loss injections is often temporary and reversible — it typically improves weeks or months after discontinuing treatment or once your body adjusts to the medication.
Clinically BackedWeight Loss
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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.
Practical Steps to Manage Hair Loss on Mounjaro
Nutrition support: Ensure adequate protein, iron, zinc, and B vitamins — all essential for hair growth. Consider discussing a referral to a dietitian with your GP. Gentle hair care: Use mild shampoos, avoid tight hairstyles, and minimise heat styling. Hydration: Drink sufficient water daily, especially important when taking Mounjaro. Medical review: If hair loss is severe or distressing, speak to your prescriber. They may adjust your dose, pause treatment temporarily, or explore alternatives like Wegovy or NHS-supported weight management programmes. Stress management also matters — weight loss medication can cause mild stress, which may worsen hair loss. Use our progress tracker to monitor overall health changes alongside any side effects you notice.
- 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 on Mounjaro permanent?
No. Hair loss caused by Mounjaro is typically temporary and reversible. It usually improves weeks to months after stopping the medication or once your body adapts. Hair regrowth generally occurs naturally without specific treatment required. Discuss any concerns with your GP.
Why does Mounjaro cause hair loss more than Wegovy?
Mounjaro's dual GIP and GLP-1 mechanism may affect nutrient absorption differently than Wegovy's single GLP-1 action. Both can slow gastric emptying, affecting mineral absorption. Individual responses vary significantly — some people on Wegovy experience hair loss, whilst others on Mounjaro don't. Genetics and baseline nutrition play major roles.
What vitamins should I take to prevent hair loss on Mounjaro?
Common supportive nutrients include iron, zinc, vitamin B12, and biotin. However, don't self-supplement without guidance — excess supplementation can be harmful. Discuss with your GP or a dietitian who understands weight loss medication. They may recommend bloodwork to identify specific deficiencies before recommending supplements.
Should I stop Mounjaro if my hair is falling out?
Do not stop without medical guidance. Speak to your prescriber first — they may suggest pausing treatment, adjusting your dose, or adding nutritional support. In many cases, hair loss resolves whilst continuing treatment. Your prescriber will help you weigh the benefits of weight management against side effects.
Does hair loss happen on all GLP-1 medications?
Hair loss is reported with both Mounjaro (tirzepatide) and Wegovy (semaglutide), though it's not universal. Liraglutide (Saxenda) also lists it as a possible side effect. Individual experiences vary widely — some people experience no hair loss at all. gradual weight management itself can trigger telogen effluvium (temporary shedding), regardless of medication type.
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.