You’re on a late shift when 10-year-old Maria arrives after falling off a trampoline and landing on her elbow. She has a background of renal dysplasia with an eGFR of 25 mL/min/1.73 m². She’s crying, distressed and clearly in pain.
The nurse turns to you and asks you: “What pain relief can we give her?”
Pain is a symptom we’re usually comfortable managing in the emergency department. But when a child has renal impairment, choosing the right analgesia can feel like walking a tightrope. We want to relieve their pain effectively, but we also fear worsening their already fragile renal function.
Children with renal disease still present to the ED with all the usual painful conditions we see daily: fractures, burns, abdominal pain… or even just a simple otitis media. They deserve the same timely and compassionate pain management as any other child- yet many clinicians hesitate, unsure of the risks to their kidneys. And, although renal advice may be just a phone call away, waking the on-call consultant at 4 am to check whether paracetamol is safe is something most of us would like to avoid.
With that in mind, let’s explore the guidance and evidence behind analgesia in paediatric renal impairment to help us prescribe safely, confidently, and compassionately.
Why is analgesia different in children with renal impairment?
Many analgesics depend on the kidneys for clearance. When the kidneys are not functioning optimally, medications or their metabolites can accumulate, leading to prolonged effects and increased risk of toxicity. Other analgesics, such as NSAIDs, have direct nephrotoxic effects, reducing renal perfusion and potentially worsening pre-existing renal dysfunction.
When we talk about renal impairment, we don’t just mean children on dialysis. This applies to both patients with AKI and CKD – whether it’s a child with CKD stage 5, or an otherwise healthy child now in AKI after a bad bout of gastroenteritis, thoughtful prescribing can make a real difference to their long-term kidney outcomes
Despite the importance of this issue, paediatric-specific evidence is remarkably limited. Much of the guidance is extrapolated from adult studies or based on expert consensus rather than robust randomised trials, leaving clinicians navigating grey areas when deciding on the safest analgesic approach. Here, we will explore the available options and how to use them most effectively.
The options: what’s safe, what’s not and why
Paracetamol- a reliable first-line option
Paracetamol remains the first-line analgesic for mild to moderate pain, and thankfully it’s safe in all stages of renal impairment. Although its half-life may be slightly prolonged in renal impairment, therapeutic dosing does not result in harmful accumulation.
Current paediatric guidance indicates that dose adjustments are not required, even in advanced CKD, though the dosing interval can be increased in more severe impairment, for example:
eGFR <50 mL/min/1.73 m²: give every 6 hours
eGFR <10 mL/min/1.73 m²: give every 8 hours
Bottom line: Paracetamol is safe and should be your go-to first-line analgesic.
NSAIDs- avoid where possible
NSAIDs reduce pain and inflammation by blocking prostaglandin synthesis. But prostaglandins also help maintain renal blood flow, and blocking this leads to vasoconstriction, reduced perfusion and further reduction in glomerular filtration, which can be particularly risky in children whose kidneys are already compromised.
Beyond their direct renal effects, NSAIDs can also exacerbate hypertension and increase the risk of gastrointestinal bleeding – both of which are best avoided in children with chronic kidney disease.
These adverse effects on the kidneys are well demonstrated in the literature:
- A large cohort study reported that NSAID exposure was associated with a 63% increase in AKI risk, accounting for 11% of all hospital-acquired AKI in children in China.
- A systematic review and meta-analysis of seven paediatric studies found that NSAIDs increased the risk of AKI by more than 55% in hospitalised children.
- Although limited in size, a prospective study conducted in Argentina among dehydrated children with acute gastroenteritis found that ibuprofen administration was associated with a 2.5-fold increased risk of AKI.
Bottom line: NSAIDs should be avoided wherever possible, with safer alternatives used instead.
Opioids
Where paracetamol isn’t enough, opioids become necessary. The key challenge is that many opioids have active metabolites that accumulate in renal dysfunction.
Below is a breakdown of common opioids and their suitability.
Morphine: use an alternative if available
Morphine’s major issue is not the drug itself; only a small amount is excreted unchanged by the kidneys. Rather, it produces active metabolites – morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G), which rely on the kidneys for clearance (14). In CKD, these can accumulate quickly, and children can develop morphine toxicity even when standard doses are used.
Current guidance is that it is generally best avoided, but if no alternative is available, a dose reduction and increased dosing interval should be considered for patients with CKD 3 or worse. Regular observations for these patients are advised to look out for signs of sedation or respiratory depression.
eGFR 30-50 (CKD 3): reduce dose by 25% and change dosing interval to every 6hours
eGFR <30 (CKD 4): reduce dosing by 25-50% and change dosing interval to every 8 hours
Codeine: very rarely used
Codeine is a prodrug that requires conversion by cytochrome P450 enzymes into active metabolites, including codeine glucuronide, morphine and morphine glucuronides.
In renal impairment, the clearance of both codeine and its metabolites is significantly reduced. Because it ultimately converts to morphine, it carries the same risks of metabolite accumulation and toxicity seen with morphine. For this reason, codeine is rarely recommended in children with renal impairment.
Oxycodone: a safe oral opioid
Oxycodone is predominantly metabolised by the liver (~90%), which makes it a more suitable option than many other opioids in children with renal impairment. However, reduced renal function can still lead to unpredictable prolongation of its half-life, and cases have reported significant CNS depression even at standard doses in children with renal disease. For this reason, dose reduction and slow, cautious titration are recommended.
eGFR 10–50 (CKD 3-4 or AKI stage 1-2): usual mg/kg dosing, but use a longer interval of 8-12 hours
eGFR <10 or AKI stage ≥3: 0.025 – 0.05 mg/kg every 8- 12 hours, with a maximum starting dose of 2.5 mg.
Fentanyl- a safe opioid option available in different preparations
Fentanyl is almost entirely metabolised by the liver into inactive metabolites, with only a minimal proportion excreted unchanged by the kidneys. This makes it one of the safer opioid options for children with renal impairment, as its pharmacokinetics remain relatively predictable even in advanced CKD.
eGFR 10–50: reduce dose by ~50%
eGFR <10: reduce dose by ~75%
Paediatric data on fentanyl use in renal impairment is limited, and most evidence is drawn from adult populations. A small perioperative case series involving 16 adults with end-stage renal disease found IV fentanyl to be safe, effective, and well tolerated, with few unexpected adverse events.
Despite the limited paediatric evidence, fentanyl is widely used in children with CKD or AKI because it is effective, predictable and requires only modest dose adjustment. It is also available in multiple formulations, including intranasal, which makes it particularly useful in the ED for rapid analgesia and procedural pain control.
Bottom line: For children with renal impairment use oxycodone or fentanyl over morphine or codeine. Start lower, titrate slowly and monitor closely for toxicity.
Adjuncts and Alternatives
Local and Regional Anaesthesia
Local anaesthetics are generally safe in renal impairment and remain essential for procedural pain. Topical preparations or local infiltration can be used where appropriate.
Regional anaesthesia (e.g., femoral nerve blocks) is generally underused in paediatrics but can significantly reduce the need for systemic opioids. These can be performed in collaboration with anaesthetic or pain teams.
Non-pharmacological Strategies
As with all children, non-drug approaches can be used to help distraction and reduce the perception of pain.
Examples include:
- Play therapy
- Distraction tools (bubbles, iPads, VR, picture books)
- Parental involvement
- Child-centred communication
- Comfort positioning
These measures can reduce distress, improve cooperation and often reduce analgesic requirements.
Putting it all together for a step-wise approach…
She has an eGFR of 25 mL/min/1.73 m². You start by prescribing some paracetamol and avoid ibuprofen. Her pain persists so you choose oral oxycodone, using 50% of the standard BNFc dose with an extended dosing interval.
Her pain improves significantly, allowing her to undergo X-ray imaging comfortably and continue with her fracture management.
This thoughtful approach gives Maria the relief she deserves while keeping her kidneys safe.
Take home messages:
Children with renal impairment still need effective pain relief- their physiology may be different, but their need for comfort is not
Paracetamol is safe across all stages of renal impairment.
When opioids are needed, choose safer agents like oxycodone or fentanyl over morphine or codeine. Always start with a lower dose, titrate slowly and monitor closely for toxicity.
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