Prescribing IV fluids

Prescribe fluids like drugs, using the 5 Rs: resuscitation, routine maintenance, replacement, redistribution, reassessment.

Sepsis resuscitation follows NG253 (250 mL boluses), not the general 500 mL bolus.

Act now

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Resuscitation (non-sepsis): 500 mL crystalloid containing sodium 130–154 mmol/L over less than 15 minutes, then reassess.

Does the patient need fluid? Assess intake, losses (vomiting, drains, stoma, fever), fluid balance, weight, U&E.
Signs of need for resuscitation: systolic BP <100, HR >90, capillary refill >2 s, RR >20, NEWS ≥5, passive leg raise response.

Routine maintenance per day: 25–30 mL/kg water; about 1 mmol/kg each of sodium, potassium and chloride; 50–100 g glucose to limit starvation ketosis.
Consider 20–25 mL/kg/day for older or frail patients, renal or cardiac impairment, or malnutrition; use ideal body weight in obesity.
Replacement: add ongoing losses on top of maintenance, matched to what is being lost.
Switch to oral or enteral routes as soon as possible.

Needing more than 2 L for resuscitation, signs of overload, or complex electrolyte problems: senior review.

Maintenance example for 70 kg: about 2–2.1 L/day, e.g. 0.18% sodium chloride/4% glucose with 27 mmol/L KCl — follow local fluid policy.

Hyponatraemia risk with hypotonic fluids — check Na⁺ daily.

Check the BNF and your local formulary before prescribing.

Written to current guidance (NICE CG174, NG253) · sources checked 14 Nov 2026. We watch NICE for updates weekly.

Sources (2)

Reviewed by Aboodee Alhasso, MPharm MRCPharm IP on 14 Nov 2026

For healthcare professionals, as an aid to clinical judgement — not a substitute for it. Follow your local policy and ask a senior when in doubt.