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Electrolyte — Potassium Supplement Pregnancy: Safe to use — monitor levels; essential electrolyte

Potassium Chloride (IV)

Brand names: KCl, Potassium Chloride Infusion

Adult dose

Dose: Mild-moderate hypokalaemia: 20–40 mmol over 2–4 hours; Severe hypokalaemia (K+ <2.5 or arrhythmia): up to 40 mmol/hour via central line
Route: IV (diluted) — NEVER undiluted bolus
Frequency: Titrated to repeat serum K+ measurements
Max: 40 mmol/hour (critical care only, via central line with continuous ECG monitoring)
Maximum peripheral infusion: 20 mmol in 100 mL over 1 hour via large peripheral vein. Central line for rates >20 mmol/hour. NEVER give as undiluted bolus — fatal cardiac arrhythmia. Target serum K+ >4.0 mmol/L in cardiac patients and ICU.

Paediatric dose

Dose: 0.5 mmol/kg
Route: IV
Frequency: Over minimum 1 hour
Max: 1 mmol/kg/hour
Max peripheral concentration: 40 mmol/L. Max rate: 0.5 mmol/kg/hour (peripheral) or 1 mmol/kg/hour (central). Under close monitoring only.

Dose adjustments

Renal

Use with extreme caution in renal impairment — high risk of hyperkalaemia. Reduce dose; monitor K+ frequently.

Hepatic

No specific adjustment but monitor K+ due to secondary hyperaldosteronism in cirrhosis.

Paediatric weight-based calculator

Max peripheral concentration: 40 mmol/L. Max rate: 0.5 mmol/kg/hour (peripheral) or 1 mmol/kg/hour (central). Under close monitoring only.

Clinical pearls

  • NPSA National Patient Safety Alert: concentrated KCl ampoules must NOT be stored on wards — must be dispensed by pharmacy pre-diluted. Failure to comply = never event.
  • In ICU, replete both K+ AND Mg²⁺ simultaneously — hypomagnesaemia causes refractory hypokalaemia (Mg required for K+ reabsorption in Loop of Henle)
  • Continuous ECG monitoring mandatory during high-rate K+ replacement (>10 mmol/hour)

Contraindications

  • Hyperkalaemia
  • Oliguria/anuria
  • Addison's disease
  • Undiluted IV bolus administration

Side effects

  • Hyperkalaemia (life-threatening — cardiac arrhythmia, cardiac arrest)
  • Phlebitis (peripheral — caustic to veins)
  • Nausea/vomiting (oral)
  • Local pain during infusion

Interactions

  • ACE inhibitors/ARBs/spironolactone (additive hyperkalaemia — potentially fatal)
  • Digoxin (hyperkalaemia reduces toxicity — but rebound hypokalaemia after treatment re-sensitises)
  • Heparin (can cause hyperkalaemia)

Monitoring

  • Serum K+ every 1–2 hours during rapid replacement
  • Continuous ECG (peaked T waves, PR prolongation, wide QRS = toxicity)
  • Urine output
  • Serum Mg (replace if low)

Reference: BNFc; BNF 90; NPSA Patient Safety Alert 2002 (Potassium Chloride); BNFc; ICU electrolyte replacement protocols. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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