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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Shaking and Weight Loss — Understanding Medication Side Effects
Shaking or tremors can occur during weight loss, particularly when using prescription weight management medication like Mounjaro or Wegovy. If you're experiencing shaking alongside weight loss efforts, it's important to understand whether this is a medication side effect or another health concern. This guide explains what causes shaking with weight loss injections, UK-licensed medication options available through the NHS and privately, and when to speak with your GP. Whether you're considering prescription weight loss medication or already using it, understanding potential side effects helps you make informed decisions about your weight management journey.
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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.
UK Prescription Weight Loss Medications and Side Effects
Three GLP-1 and GIP/GLP-1 medications are currently licensed for weight management in the UK. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist injected once weekly, available in doses from 2.5 mg to 15 mg. Wegovy (semaglutide) is a once-weekly GLP-1 injection with doses up to 2.4 mg. Saxenda (liraglutide) is a daily GLP-1 injection up to 3 mg per day. Clinical trials show these medications help with weight loss averaging 15–21% of body weight, though individual results vary significantly. Common side effects include nausea, diarrhoea, constipation, and stomach pain — these typically improve as your body adjusts. Tremors or shaking are less common but documented side effects, particularly during dose escalation or in the first few weeks of treatment. Your prescriber should be informed of any shaking or tremors so they can assess whether it relates to the medication or another cause.
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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.
NHS Access vs Private Prescription Weight Loss in the UK
In the UK, prescription weight loss medication is accessed through two routes. NHS access is through specialist tier 3 or tier 4 weight management services, typically requiring a GP referral. Availability varies significantly by region and waiting times can be lengthy. Private access is available through GPhC-registered online prescribers following an online clinical assessment — no NHS referral needed. To find out if you're eligible, you can use our free BMI calculator above to check your current BMI, then discuss options with your GP or arrange a private consultation. Eligibility generally requires a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes or high blood pressure. If you experience shaking or concerning symptoms while on weight loss medication, contact your prescriber or GP immediately rather than stopping treatment without guidance.
- 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.
Can Mounjaro or Wegovy cause shaking or tremors?
Tremors are not listed as very common side effects of Mounjaro or Wegovy, but they have been reported. Shaking may occur during dose escalation or early treatment. Any new or unusual symptoms should be reported to your prescriber immediately. They can assess whether the symptom is medication-related or warrants investigation.
How do I know if I'm eligible for prescription weight loss medication on the NHS?
Generally, adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions, may be eligible. South Asian, Chinese, Black African, or Black Caribbean adults may have lower thresholds. Your GP can assess your eligibility and discuss referral to specialist weight management services in your area.
What's the difference between accessing weight loss medication through the NHS versus privately?
NHS access requires GP referral to specialist services and is free but involves waiting lists that vary by region. Private access is faster, available without NHS referral, and requires payment (typically £129–£320 monthly). Both routes require a clinical assessment and prescription from a licensed prescriber.
Should I stop taking Mounjaro or Wegovy if I develop shaking?
Do not stop prescription weight loss medication without guidance from your prescriber. Contact your GP or prescriber immediately if you experience shaking or other concerning symptoms. They may adjust your dose, investigate other causes, or recommend alternative treatment. Never stop abruptly without professional advice.
Can I track my weight loss progress while using prescription medication?
Yes. Use our free progress tracker on this site to log your weight, measurements, and how you feel throughout your weight loss journey. Tracking helps you and your prescriber see results over time and monitor how you're responding to treatment, including any side effects like shaking.
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.