Synopsis
Select and reassess an analgesic regimen while obtaining the appropriate image, accounting for body weight, organ function, pregnancy and diagnostic uncertainty.
- In the NICE sequence, use an appropriate NSAID first, intravenous paracetamol if an NSAID is contraindicated or insufficient, and an opioid if both earlier choices are unsuitable or inadequate; antispasmodics are not recommended.
- For adult suspected colic, NICE specifies low-dose noncontrast CT within twenty four hours; pregnancy uses ultrasound instead, and children under sixteen start with urgent ultrasound.
- Prescribe intravenous paracetamol in both milligrams and millilitres and count all other paracetamol; weight at or below fifty kilograms changes the dose and daily ceiling.
Key red flags
Uncontrolled pain despite appropriate medicines needs urgent urological reassessment for drainage or stone treatment.
Sedation, falling respiratory rate or oxygenation after an opioid requires immediate assessment and withholding further opioid doses.
Reasoning priorities
Identify the stone and assess a cause of pain requiring a different intervention.
For suspected renal colic in adults, arrange the NICE examination within twenty four hours. Discuss an alternative protocol with radiology if the leading concern is vascular, inflammatory or another non-stone diagnosis. Do not add contrast phases routinely merely because pain is severe.
Worked reasoning
A forty eight kilogram adult woman has suspected colic and a previous NSAID-associated bleeding ulcer.
- She is not pregnant, has normal renal and hepatic function, no dehydration or alcohol risk, and has taken no paracetamol that day. The bleeding history excludes diclofenac. Her pain score is seven out of ten and repeated vomiting makes an oral initial regimen unreliable, so intravenous paracetamol is selected without a trial of another NSAID.
- Using Paracetamol ALTAN 10 mg/ml, the prescribed dose is 15 mg/kg: 48 multiplied by 15 equals 720 mg, corresponding to 72 ml. It is infused over fifteen minutes. Her weight-based daily ceiling is 60 mg/kg, or 2,880 mg from every source, which remains below the product’s 3 g ceiling for this weight group; further doses must be at least four hours apart.
- Pain falls to two out of ten and vomiting settles, so no opioid is required. Low-dose noncontrast CT that day identifies a three millimetre distal ureteric stone without concerning obstruction. Examination and the scan identify no alternative emergency, and she subsequently retains oral fluid.
- After clinician review, she leaves with a reconciled oral analgesia plan and scheduled stone follow-up, understanding that the intravenous dose counts towards the same day’s total. She recovers the stone five days later; follow-up confirms symptom resolution and stable renal function. The record includes both the successful dose calculation and the observed clinical outcome.
Key medicines
Voltarol 75 mg/3 ml intramuscular diclofenacAn adult renal-colic dose is one 75 mg deep intragluteal injection. If necessary the renal-colic schedule permits one further ampoule after thirty minutes; the combined daily diclofenac maximum is 150 mg and ampoule treatment must not exceed two days.Do not administer for renal or hepatic failure, active/recurrent ulcer or bleeding, prior NSAID-related gastrointestinal bleeding, established ischaemic/cerebrovascular or peripheral arterial disease, or NYHA II–IV heart failure. Exclude NSAID-triggered respiratory or allergic reactions and product/metabisulphite hypersensitivity. Avoid duplicate NSAIDs; assess anticoagulants, steroids, SSRIs, methotrexate, lithium and ACE inhibitor/diuretic renal interactions. Use additional caution in frailty, low weight and volume depletion. Stop for bleeding, rash or organ deterioration. Ampoules are not recommended in children; pregnancy requires a separate decision, with fetal renal/ductal risk from twenty weeks and third-trimester contraindication. Never give this product as an intravenous bolus. The selected Voltarol label states that it should not be administered during breastfeeding.
Paracetamol ALTAN 10 mg/ml intravenous infusionFor both adult weight bands below, infuse each dose over at least fifteen minutes, leave at least four hours between doses and give no more than four doses in twenty four hours. Above 50 kg without hepatotoxicity risk, give 1 g as 100 ml per dose, maximum 4 g/day. At more than 33 kg up to and including 50 kg, give 15 mg/kg as 1.5 ml/kg per dose, maximum 60 mg/kg/day capped at 3 g; apply the renal interval and hepatic-risk limits in the cautions.At creatinine clearance 30 ml/min or less, separate doses by at least six hours. Above 50 kg with hepatocellular impairment, chronic alcohol use, malnutrition or dehydration, the daily maximum is 3 g; severe hepatocellular insufficiency or paracetamol/propacetamol/product hypersensitivity excludes treatment. Count every oral, rectal and IV paracetamol source and prescribe both mg and ml. Review probenecid, which reduces clearance, and anticoagulant monitoring during continued use; flucloxacillin and glutathione-depletion states increase pyroglutamic-acidosis risk. Use the smaller of applicable weight/risk limits and switch to an appropriate oral regimen when feasible. This adult example does not supply neonatal or paediatric dosing.