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 and Retinopathy — UK Health Guidance
Retinopathy is damage to the blood vessels in the retina of the eye, commonly linked to poorly controlled blood sugar in type 2 diabetes. If you're taking Mounjaro (tirzepatide) or considering it, you may have questions about eye health and vision safety. This guide explains the relationship between Mounjaro and retinopathy, what the evidence shows, and how to protect your vision whilst on treatment. Always discuss any eye concerns with your GP or eye care specialist before starting any new medication.
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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.
Understanding Retinopathy and Mounjaro
Retinopathy occurs when high blood sugar damages tiny blood vessels in the retina, potentially affecting vision. In people with type 2 diabetes, improved blood sugar control often reduces retinopathy risk significantly. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist that helps regulate blood sugar and supports weight loss — both factors that may improve metabolic health.
The UK Medicines and Healthcare products Regulatory Agency (MHRA) has noted that in clinical trials, some patients using GLP-1 medications (including tirzepatide) experienced changes in vision or worsening of diabetic retinopathy. However, this is not unique to Mounjaro — it can occur with any medication that rapidly improves blood sugar control. When glucose levels drop quickly, the eye may temporarily experience blurred vision or other changes. This is typically temporary, but rapid improvements in blood sugar control in people with existing retinopathy require careful monitoring by an eye care professional.
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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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Protecting Your Vision on Mounjaro
If you have type 2 diabetes or a history of diabetic retinopathy, inform your prescriber before starting Mounjaro. Request a baseline eye examination with an optometrist or ophthalmologist before treatment begins. During Mounjaro treatment, attend regular eye check-ups as recommended by your eye care specialist — typically every 1–2 years if you have no retinopathy, or more frequently if you have existing eye disease.
Maintain good blood sugar control using the UK GLP-1 weight loss calculator to track your progress and celebrate improvements. Manage other risk factors: keep blood pressure and cholesterol within healthy ranges using our BMI calculator and weight converter for context. Report any visual changes — blurred vision, floaters, or dark spots — to your GP or eye specialist immediately. These symptoms may be temporary, but they require professional assessment.
Weight loss achieved through Mounjaro may also reduce diabetes-related eye risk by improving overall metabolic health. When combined with lifestyle changes — diet, exercise, and regular monitoring — Mounjaro can be part of a comprehensive approach to diabetes management. However, vision protection requires active participation: attend your eye appointments, report changes promptly, and work closely with your diabetes care team and eye specialist throughout your tirzepatide treatment journey.
- 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 cause retinopathy?
Mounjaro does not directly cause retinopathy, but rapid improvements in blood sugar control can temporarily affect vision in people with existing diabetic retinopathy. This is a known effect of effective diabetes treatment. Always inform your prescriber if you have a history of eye disease before starting Mounjaro.
What should I do if my vision changes on Mounjaro?
Report any changes in vision — blurred sight, floaters, or dark spots — to your GP or eye specialist immediately. Do not stop Mounjaro without medical advice. Your eye care professional can assess whether changes are temporary vision adjustments or require management modifications.
Do I need eye tests before starting Mounjaro?
Yes. If you have type 2 diabetes or any history of retinopathy, request a baseline eye examination before starting Mounjaro. This allows your eye specialist to monitor any changes during treatment and distinguish between medication effects and underlying disease progression.
Is Mounjaro safer than other GLP-1 medications for eyes?
Mounjaro is a dual GIP and GLP-1 agonist, while medications like Wegovy contain only GLP-1. Both types may cause temporary vision changes when blood sugar improves rapidly. Safety depends on individual health factors and close monitoring by your healthcare team.
How often should I have eye check-ups on Mounjaro?
If you have no retinopathy history, routine eye tests every 1–2 years are typically recommended. If you have existing diabetic retinopathy, your eye specialist may recommend more frequent monitoring — discuss the appropriate schedule with them based on your individual risk and disease status.
Ready to take control of your weight loss journey?
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