Understanding the stages of CKD
CKD is classified into five stages based on your eGFR (a measure of how well your kidneys filter blood).
Your stage helps determine the level of monitoring you’ll need while taking Wegovy.
| Stage |
eGFR |
Wegovy consideration |
| G1 (90+) |
Normal function |
Safe with standard monitoring |
| G2 (60-89) |
Mild impairment |
Safe with standard monitoring |
| G3a (45-59) |
Mild-moderate impairment |
Safe with closer monitoring |
| G3b (30-44) |
Moderate-severe impairment |
Requires specialist input |
| G4 (15-29) |
Severe impairment |
Nephrologist approval needed; trial data is limited at this stage |
| G5 (below 15) |
Kidney failure |
Not recommended1 |
Most people with CKD stages 1 to 3 can take Wegovy safely with appropriate monitoring.
Stages 4 to 5 fall outside the population studied in most trials, which is why specialist nephrology input is needed before starting.
Dehydration: the main risk for people with CKD
In October 2024, the MHRA issued a Drug Safety Update warning that gastrointestinal side effects from GLP-1 receptor agonists can lead to dehydration and, in some cases, kidney damage requiring hospitalisation.5
In clinical trials, nausea affected around 44% of people taking Wegovy, vomiting around 25%, and diarrhoea around 30%.
These side effects are most common during dose increases and usually settle over time.
People with CKD are particularly vulnerable because their kidneys have less capacity to cope with fluid loss. To manage this:
- Drink small, frequent sips of water throughout the day rather than large amounts at once
- If nausea makes plain water unappealing, try ginger tea or water with a small amount of lemon
- Contact your healthcare team if you can’t keep fluids down for more than 24 hours
- Watch for signs of dehydration: reduced urine output, dark urine, dizziness, or dry mouth
If you have advanced CKD and your nephrologist has asked you to restrict fluids, follow their guidance rather than the general advice above.
Why semaglutide may protect kidney function
The kidney benefits seen in trials aren’t only due to weight loss or better blood pressure, though both help.
Semaglutide appears to act on the kidney directly through several pathways.9
GLP-1 drugs reduce the strain on damaged kidneys by slowing the filtering process, which helps protect remaining kidney function.
It eases the pressure on the blood vessels that do the filtering. It also reduces inflammation and oxidative stress, both of which accelerate kidney damage.
These mechanisms are similar in principle to those of SGLT2 inhibitors (such as dapagliflozin and empagliflozin), the class of medications shown from 2020 onwards to slow CKD progression and reduce the risk of kidney failure.
Semaglutide and SGLT2 inhibitors appear to work through different but complementary pathways, and recent trial data suggest their benefits may be additive when used together.9
Because of these direct effects on the kidneys, nephrology guidance is now starting to position GLP-1 receptor agonists as kidney-protective therapy in their own right, not only as weight-loss or diabetes medications.
What the trials show
Three major clinical trials have tested semaglutide in people with kidney disease or at risk of it.
The FLOW trial
The FLOW trial, published in the New England Journal of Medicine in 2024, tested subcutaneous semaglutide 1.0 mg (the Ozempic dose, not the higher Wegovy dose) in 3,533 people with type 2 diabetes and CKD.2
The trial was stopped early because the results were clear. People taking semaglutide had a 24% lower risk of major kidney events, including kidney failure, sustained eGFR decline, and kidney-related death.2
Their kidney function declined 1.16 ml/min per year more slowly than those on placebo, and a key marker of kidney damage called UACR (the amount of albumin leaking into urine) improved by 38%.2
The SELECT trial kidney outcomes
The SELECT trial tested semaglutide at the Wegovy dose (2.4 mg) in 17,604 people with obesity and cardiovascular disease, without diabetes.3
An analysis of kidney outcomes found a 22% lower risk of serious kidney problems, including kidney failure and sustained eGFR decline.
In participants with already reduced kidney function (eGFR below 60), the benefit was greater, with kidney function declining more slowly than in those on placebo.
The SMART trial
Published in Nature Medicine in 2024, it tested semaglutide 2.4 mg specifically in 101 people with CKD and obesity, without diabetes.4
After 24 weeks, UACR fell by 52% compared to placebo.4 An early dip in eGFR was observed, similar to what’s seen with SGLT2 inhibitors. This is thought to reflect beneficial changes in kidney blood flow rather than harm, and eGFR returned to baseline once treatment finished.
| Trial |
Dose and population |
Key kidney outcome |
| FLOW (Perkovic et al., 2024)2 |
1.0 mg; T2D + CKD; n=3,533 |
24% reduction in major kidney events; 38% UACR reduction |
| SELECT (Colhoun et al., 2024)3 |
2.4 mg; obesity + CVD, no diabetes; n=17,604 |
22% reduction in composite kidney endpoint |
| SMART (Apperloo et al., 2024)4 |
2.4 mg; CKD + obesity, no diabetes; n=101 |
52% UACR reduction at 24 weeks |
Monitoring while on Wegovy
Your healthcare team should monitor your kidney function more closely when you start Wegovy.
- Kidney function (eGFR and creatinine) every three to four months initially, rather than the usual six to twelve months for stable CKD
- Electrolytes (sodium, potassium) more frequently, particularly if you experience significant nausea or vomiting
- Check blood pressure regularly, as weight loss often improves blood pressure, and your medication doses may need reducing
- A full medication review as you lose weight, since doses of blood pressure tablets and other CKD medications may need adjusting
Your GP and nephrologist should coordinate this monitoring jointly, rather than either clinician working in isolation.
Foods to focus on
Nutrition for people with CKD is more complex than general healthy-eating advice.
The right approach depends on your stage of CKD and blood results, so ask your GP for a referral to a renal dietitian for personalised guidance.
Eating the right amount of protein
Weight loss means you need adequate protein to preserve muscle mass. But in later stages of CKD, high protein intake can increase the workload on your kidneys.
For CKD stages 1 and 2, protein intake usually doesn’t need to be restricted. Good sources include chicken, fish, eggs, lentils, and tofu.
From stage 3b onwards, your renal team may recommend moderating protein to around 0.8 g per kilogram of body weight per day. This doesn’t mean avoiding it entirely, but eating more moderate amounts in each meal, and avoiding high-protein snacks between.
A renal dietitian can help work out the right amount for your specific situation.
Reducing sodium
Moderating salt intake helps manage blood pressure and reduce fluid retention, both important for kidney health.
Cooking from scratch where possible, checking labels, and limiting processed foods and ready meals are the most practical steps.
Herbs, spices, lemon juice, and garlic can add flavour without adding salt.
Potassium and phosphate
In early-stage CKD (stages 1 to 3a), potassium and phosphate rarely need to be restricted. Your regular blood tests will show if levels are rising.
From stage 3b onwards, you may need to moderate potassium-rich foods like bananas, oranges, and potatoes, but only if your blood tests indicate high levels.
Don’t restrict these foods without first checking your results.
Eating enough on Wegovy
Wegovy reduces appetite, which can make it hard to eat enough. This is a particular concern with CKD because malnutrition is a recognised complication of kidney disease and worsens long-term outcomes.
Prioritise protein and vegetables at each meal, and add complex carbohydrates like oats, wholegrain or sourdough bread, or sweet potato for sustained energy. Include a source of healthy fat such as olive oil, avocado, nuts, or seeds.
Aim for three balanced meals a day. If you’re skipping meals because you don’t feel hungry, we recommend eating meals that are easy to digest, like smoothies, soups, scrambled eggs, stews and other one-pot dishes.
Staying active with CKD
Physical activity is beneficial at all stages of CKD. It helps manage blood pressure, supports cardiovascular fitness, and preserves muscle mass, which is particularly relevant when losing weight on Wegovy.
Fatigue is one of the most common barriers to exercise in kidney disease, but consistency and regular movement are more important than intensity.
A small amount of activity most days does more for blood pressure, fitness, and muscle than longer sessions you can only manage occasionally.
Research on habit formation suggests that linking a new behaviour to an existing routine helps it become automatic over time.6
A 10-minute walk after dinner is a practical starting point that doesn’t require special equipment.
If fatigue makes longer sessions difficult, shorter bouts of activity throughout the day work just as well.
Three 10-minute walks add up to the same as one 30-minute walk.
Preserving muscle
Muscle wasting is common in CKD, and weight loss can sometimes accelerate it.
Resistance training, even using bodyweight exercises or light resistance bands, helps preserve muscle mass.
Bodyweight squats, wall push-ups, or seated resistance band exercises are good starting points.
You could try ‘exercise snacking’: a few squats while waiting for the kettle to boil, or calf raises during a phone call.
Gradually doing a little more as it feels manageable is the right approach.
If you have advanced CKD, speak to your nephrologist or a physiotherapist before starting.
Looking after your mental health
Studies in dialysis and pre-dialysis populations consistently report higher rates of anxiety and depression than the general population, with kidney-disease distress affecting a substantial minority of people.
Several things contribute. Dietary restrictions, particularly around potassium, phosphate, and protein, can make eating feel stressful rather than enjoyable.
Regular blood tests and monitoring appointments are a constant reminder that something’s wrong. And the uncertainty about whether your kidney function will stay stable or decline can be hard to cope with.
Starting Wegovy can bring its own worries, particularly about how the medication will affect your kidneys or what side effects to expect during dose escalation. Changes in appetite and body shape can also affect how you feel about yourself.
These responses are normal. They don’t mean you’re not coping.
Speak to your GP if you’re struggling. Many specialist renal services have psychologists or counsellors attached, and you can ask to be referred.
You can also contact the Kidney Care UK helpline for emotional support and practical guidance.
When to speak to your GP
Contact your GP, nephrologist, or prescriber if you experience:
- Reduced urine output or dark-coloured urine, which could suggest dehydration
- Persistent nausea or vomiting that prevents you from keeping fluids down
- Swelling in your ankles, legs, or around your eyes (could indicate worsening fluid retention)
- Significant or rapid changes in blood pressure
- Muscle cramps, weakness, or irregular heartbeat (possible signs of electrolyte imbalance)
- Unexplained fatigue that’s worse than your usual CKD-related tiredness
- Blood in your urine
- Feelings of anxiety, low mood, or being overwhelmed by managing your condition
If you’re unable to keep any fluids down for more than 24 hours, seek urgent medical advice. Dehydration can cause rapid kidney function decline in people with CKD.
Frequently asked questions
Is Wegovy safe if I have CKD?
For most people with CKD stages 1 to 3, yes. The Wegovy SmPC confirms no dose adjustment is needed for mild, moderate, or severe renal impairment.1
It isn’t recommended for end-stage renal disease. You’ll need closer monitoring than someone without CKD, particularly for dehydration.
Can Wegovy improve my kidney function?
Three clinical trials suggest semaglutide may protect kidney function.
The FLOW trial showed a 24% reduction in major kidney events, and the SMART trial showed a 52% reduction in urinary albumin leakage.2,4
However, Wegovy isn’t licensed in the UK specifically for kidney protection.
Will I need extra blood tests on Wegovy?
Yes. Your GP should check your kidney function (eGFR), electrolytes, and blood pressure more frequently when you start Wegovy, particularly during dose escalation. Every three to four months is a reasonable starting schedule.
What’s an eGFR dip, and should I worry about it?
Some people experience a small drop in eGFR in the first few weeks of treatment. This was seen in the SMART trial and is also common with SGLT2 inhibitors.4
It’s thought to reflect changes in pressure within the kidney rather than harm, and eGFR usually stabilises or returns to baseline. Your nephrologist will know what to look for.
Can I take Wegovy alongside an SGLT2 inhibitor?
Yes, and the combination may offer additional kidney protection.
Recent FLOW trial analyses suggest that semaglutide’s kidney benefits are observed regardless of whether someone is also on an SGLT2 inhibitor, and the two drug classes appear to act through complementary pathways.9
Your nephrologist should review the combination, particularly to manage the risk of dehydration, since both can affect fluid balance.
Should I tell my nephrologist before starting Wegovy?
Yes. If you’re under nephrology follow-up, your nephrologist needs to know before you start, regardless of whether the prescription is private or NHS.
They can advise on monitoring, flag any interactions with your current medications, and adjust the schedule of your kidney function checks.
What if Wegovy makes me feel sick and I can’t drink enough?
Dehydration can worsen kidney function, so this needs prompt attention. Try small, frequent sips rather than large drinks.
If you can’t keep fluids down for more than 24 hours, contact your healthcare team urgently.
Do I need to eat less protein with CKD?
It depends on your CKD stage. For stages 1 and 2, protein intake usually doesn’t need to be restricted. From stage 3b onwards, your renal team may recommend moderating protein.
Will my blood pressure tablets need changing?
Possibly. Weight loss from Wegovy often improves blood pressure, so your medication doses may need to be reduced.
Your GP should monitor this and adjust doses proactively rather than waiting for problems to arise.
Can I get Wegovy on the NHS if I have CKD?
NICE recommends semaglutide for weight management in eligible adults under TA875, which requires referral to a Tier 3 specialist weight management service.10
Having CKD doesn’t disqualify you, but the specialist service will need to coordinate with your kidney team.
In practice, NHS access has been limited by service capacity since TA875 came into effect, and waiting times for Tier 3 services vary considerably across the UK.
Is exercise safe with CKD?
Yes, physical activity is beneficial at all stages of CKD. It helps manage blood pressure, preserves muscle, and improves cardiovascular fitness.
Start small and build gradually. If you have advanced CKD, check with your nephrologist first.
What’s the difference between FLOW, SELECT, and SMART?
FLOW tested semaglutide 1.0 mg in people with diabetes and CKD.
SELECT tested 2.4 mg in people with obesity and heart disease, without diabetes.
SMART tested 2.4 mg in people with CKD and obesity, without diabetes.
All three showed benefits of semaglutide on kidney function, with SMART being the most directly relevant to Wegovy users with CKD because it used the Wegovy dose in the right population.
Does Second Nature accept people with CKD?
Second Nature doesn’t currently accept people with CKD onto its medication-supported programme because the level of monitoring required exceeds what the programme can provide.
People with CKD need coordination with nephrology services, which is best managed through the NHS or specialist providers.
Take home message
Wegovy can be taken by most people with CKD, with no dose adjustment needed for mild, moderate, or severe renal impairment. It isn’t recommended for end-stage renal disease.
The evidence for semaglutide’s kidney benefits is strong and growing. Three major trials have shown reduced kidney events, slower eGFR decline, and significant improvements in markers of kidney damage.
The main risk is dehydration from gastrointestinal side effects. People with CKD should be particularly vigilant about staying hydrated and should contact their healthcare team if they can’t keep fluids down.
Nutrition needs more thought with CKD, particularly around protein intake in later stages. Work with a renal dietitian if possible, and don’t restrict potassium or phosphate without checking your blood results first.
Second Nature’s programme combines medication support with personalised nutrition guidance from registered dietitians and nutritionists, built around a balanced plate of vegetables, protein, complex carbohydrates, and healthy fats.
A peer-reviewed study published in JMIR Formative Research found that active subscribers on Second Nature’s semaglutide-supported programme lost an average of 19.1% of their body weight at 12 months, with 77.7% achieving at least 10% weight loss.7
Second Nature's Mounjaro and Wegovy programmes
Second Nature provides Mounjaro or Wegovy as part of our Mounjaro and Wegovy weight-loss programmes.
Why choose Second Nature over other medication providers, assuming you're eligible?
Because peace of mind matters.
We've had the privilege of working with the NHS for over eight years, helping people across the UK take meaningful steps toward a healthier, happier life.
Our programmes are designed to meet people where they are, whether that means support with weight loss through compassionate one-to-one health coaching, or access to the latest weight-loss medications (like Mounjaro and Wegovy) delivered alongside expert care from a multidisciplinary team of doctors, psychologists, dietitians, and personal trainers.
At the heart of everything we do is a simple belief: real, lasting change comes from building better habits, not relying on quick fixes. We're here to support that change every step of the way.
With over a decade of experience, thousands of lives changed, and a long-standing record of delivering programmes used by the NHS, we believe we're the UK's most trusted weight-loss programme.
We hope to offer you something invaluable: peace of mind, and the support you need to take that first step.
References
- Electronic Medicines Compendium. (2026). Wegovy 2.4 mg FlexTouch solution for injection in pre-filled pen: Summary of Product Characteristics.
- Perkovic, V. et al. (2024). Effects of semaglutide on chronic kidney disease in patients with type 2 diabetes. New England Journal of Medicine, 391, 109-121.
- Colhoun, H.M. et al. (2024). Long-term kidney outcomes of semaglutide in obesity and cardiovascular disease in the SELECT trial. Nature Medicine, 30(7), 2058-2066.
- Apperloo, E.M. et al. (2024). Semaglutide in patients with overweight or obesity and chronic kidney disease without diabetes: a randomized double-blind placebo-controlled clinical trial. Nature Medicine, 31(1), 278-285.
- MHRA. (2024). GLP-1 receptor agonists: reminder of potential side effects. Drug Safety Update.
- Lally, P. et al. (2010). How are habits formed: modelling habit formation in the real world. European Journal of Social Psychology, 40(6), 998-1009.
- Richards, R. et al. (2025). A remotely delivered GLP-1RA-supported specialist weight management program in adults living with obesity: retrospective service evaluation. JMIR Formative Research, 9, e72577.
- Hirst, J.A. et al. (2020). Prevalence of chronic kidney disease in the community using data from OxRen: a UK population-based cohort study. British Journal of General Practice, 70(693), e285-e293.
- Cherney, D.Z.I. et al. (2024). The GLP-1 receptor agonist revolution comes to nephrology. Nature Reviews Nephrology.
- NICE. (2023). Semaglutide for managing overweight and obesity (TA875).
