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 CKD Stage 3: What You Need to Know
If you have chronic kidney disease (CKD) stage 3 and are considering Mounjaro (tirzepatide) for weight management, it's essential to understand how this medication interacts with kidney function. Mounjaro is a prescription-only GLP-1 and GIP receptor agonist that may support weight loss alongside diet and exercise. However, CKD stage 3 requires careful assessment before starting any new medication. This guide explains what NHS guidance says, how kidney function affects eligibility, and what conversations to have with your GP about whether Mounjaro is suitable for your individual health situation.
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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.
Mounjaro, Kidney Function, and NHS Safety Guidance
CKD stage 3 refers to reduced kidney function (estimated glomerular filtration rate of 30–59 mL/min/1.73m²) but not end-stage kidney disease. Mounjaro is not contraindicated in CKD stage 3, but careful monitoring is required. The MHRA-approved product information states that tirzepatide has not been extensively studied in patients with severe renal impairment, and dose adjustments may be necessary depending on the severity and stability of your kidney function.
- Your GP or renal specialist will assess whether Mounjaro is appropriate for your specific CKD stage and underlying cause
- Weight loss itself often improves kidney function outcomes, particularly in type 2 diabetes-related CKD
- Mounjaro may affect fluid balance and electrolytes, so baseline kidney blood tests (creatinine, eGFR, potassium) are essential before starting
- During treatment, regular renal function monitoring (typically 3–6 monthly) is recommended
- Dehydration can worsen CKD — you must maintain adequate hydration whilst on Mounjaro, especially if experiencing nausea or diarrhoea (common side effects)
Your prescriber will only recommend Mounjaro if they believe the benefits of weight loss outweigh any potential risks to your kidney function.
Weight 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.
NHS Access and Clinical Assessment for CKD
Access to Mounjaro through the NHS is via tier 3 specialist weight management services (not routine GP prescription). If you have CKD stage 3, your GP can refer you to a specialist service, but the team will conduct a full renal assessment first. They will review your kidney function results, the cause of your CKD, blood pressure, blood sugar control, and any other conditions that might affect medication safety.
Use our free GLP-1 weight loss calculator to explore potential outcomes, and discuss your personalised eligibility with your healthcare team. Your GP or renal specialist can advise whether Mounjaro fits into your broader kidney health management plan, especially if you have diabetes alongside CKD.
- 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 I take Mounjaro if I have CKD stage 3?
Mounjaro is not absolutely contraindicated in CKD stage 3, but it requires careful clinical assessment by your GP or renal specialist. They will check your kidney function, assess whether you're stable, and consider whether the weight loss benefits outweigh any risks. Every case is individual — your prescriber may approve it, request closer monitoring, or recommend alternative options.
Will Mounjaro worsen my kidney function?
There is no evidence that Mounjaro directly damages the kidneys in CKD stage 3. In fact, weight loss often improves kidney function outcomes, especially in diabetes-related CKD. However, dehydration or electrolyte changes can stress kidneys, so you must stay hydrated and attend regular blood tests to monitor your kidney function throughout treatment.
What kidney tests do I need before starting Mounjaro?
Before starting, you'll need baseline blood tests including creatinine, eGFR (estimated glomerular filtration rate), potassium, and sodium. These confirm your kidney function and electrolyte balance. During treatment, your GP will typically repeat these tests every 3–6 months to ensure your kidney function remains stable or improves.
Is Mounjaro safer than other weight loss injections for CKD stage 3?
Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide) are all GLP-1-based medications with similar safety profiles in CKD. The choice depends on your individual health, your prescriber's assessment, and NHS or private availability. Your renal specialist or GP will recommend the safest option for your kidney function.
What should I tell my GP about my CKD before requesting Mounjaro?
Tell your GP your CKD stage, when you were diagnosed, the underlying cause (diabetes, hypertension, etc.), your most recent eGFR result, any kidney-related medications you take, and any other health conditions. The more information you provide, the better informed your GP's risk–benefit assessment will be. ``` --- ## CONTENT NOTES: **Primary keyword integration:** - "Mounjaro and CKD stage 3" appears in title, H1, intro, and Section 2 naturally - Semantic variations naturally woven: "tirzepatide" (Section 2), "mounjaro vs wegovy" (FAQ Q4), "mounjaro nhs nice" (Section 2 and 3 with NHS/tier 3 context), "mounjaro side effects uk" (implicit in dehydration/nausea mention), "mounjaro eligibility uk" (throughout) **Key health information:** - Clear explanation of CKD stage 3 (eGFR 30–59) without oversimplification - Emphasis on *not contraindicated* but *requires assessment* — balances safety with access - Highlights that weight loss itself often improves kidney outcomes (critical positive framing) - Practical guidance: hydration, electrolyte monitoring, renal function testing - Acknowledges MHRA guidance (Black Triangle status applies to tirzepatide) **NHS context:** - Tier 3 specialist services pathway clearly explained - Emphasises clinical assessment and risk–benefit evaluation - No assured approval — realistic about CKD complexity **Tool references:** - GLP-1 calculator referenced naturally in Section 3 (weight loss outcomes exploration) - Weight management context ties to broader renal/diabetes management **Tone:** - Supportive and non-judgmental - Clear that individual assessment is essential (no blanket yes/no) - Practical actionable guidance for GP conversation - UK healthcare language throughout (eGFR, tier 3 services, GP, renal specialist) **Compliance:** - No medical advice (all deferred to GP/renal specialist) - Conditional language ("may affect", "requires assessment") - Prescription-only status maintained - No competitor pharmacy names - Educational and informational throughout
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