Skip to content
ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Electrolyte — Potassium Supplement Pregnancy: UK SPC section 4.6: 'There are no or limited amount of data from the use of potassium chloride in pregnant women. The use of Potassium Chloride 2 mEq/ml concentrate for solution for infusion may be considered during pregnancy if clinically needed.' Breast-feeding: 'Potassium chloride is excreted in human milk to such an extent that effects on the breastfed newborn/infants are likely. A risk to the newborns/infants cannot be excluded. A decision must be made whether to discontinue breast-feeding or to discontinue/abstain from Potassium Chloride 2 mEq/ml concentrate for solution for infusion taking into account the benefit of breast feeding for the child and the benefit of therapy for the woman.'

Potassium Chloride (IV)

Brand names: KCl, Potassium Chloride Infusion

Intravenous potassium chloride is a concentrated electrolyte preparation used to treat or prevent hypokalaemia in patients who cannot be managed by the oral route.

Adult dose

Dose: Potassium deficiency in adults for whom dietary measures or oral medication are inadequate (potassium chloride 15% w/v concentrate, 150 mg/ml = 2 mmol/ml potassium; give intravenously ONLY after dilution): dose depends on serum electrolyte levels and acid-base state. Potassium deficit (mmol) = body weight (kg) x 0.2 x 2 x (4.5 mmol/l - serum potassium). Normal daily intake is approximately 0.8 to 2 mmol of potassium per kilogram of body weight. Dilute in a suitable solution up to a maximum concentration of 3 g/l potassium chloride (40 mmol/l potassium).
Route: Intravenous infusion ONLY after dilution (infusion pump recommended, especially for higher concentrations) - never undiluted
Frequency: Slow infusion: a rate of 10 mmol/h is normally considered safe; as a general rule never faster than 20 mmol/h
Max: Rate: as a general rule never higher than 20 mmol/h. Daily: usually the maximum dose for adults should not exceed 150 mmol per day
STRENGTH (section 2): 150 mg/ml potassium chloride = 2 mmol/ml potassium; 5 ml = 10 mmol, 10 ml = 20 mmol, 20 ml = 40 mmol. '1 g of potassium chloride corresponds to 13.4 mmol or 524 mg of potassium.' This card covers this concentrate only; ready-diluted infusions and other products differ and are not covered. VERBATIM section 4.2: 'Administer intravenously only after dilution in a suitable solution, up to a maximum concentration of 3 g/l of potassium chloride (or 40 mmol/l of potassium). For therapy of severe hypokalaemia or diabetic ketoacidosis higher concentrations may be necessary; in this case, the infusion should be into a high blood flow vein and continuous ECG monitoring is advisable.' 'Dose is dependent on results of serum electrolyte levels and acid-base-state.' 'Infusion rate should not be fast, a rate of 10 mmol/h is normally considered safe. As a general rule the rate should never be higher than 20 mmol/h. Usually, the maximum dose for adults should not exceed 150 mmol per day.' 'The administration via an infusion pump is recommended, especially for solutions with higher concentrations.' SAFETY (section 4.4): 'Direct injection of potassium chloride concentrates without appropriate dilution may cause instant death.' Extravasation can cause necrotic tissue damage. Initial potassium replacement therapy should not involve glucose infusions, because glucose may cause a further decrease in the plasma-potassium concentration. PAEDIATRIC: 'The safety and efficacy of potassium chloride for paediatric patients has not been fully established.' No paediatric dose is given. The SPC's own wording in sections 4.3 and 4.6 calls the product 'Potassium Chloride 2 mEq/ml'. Text came from a PDF and has odd spacing in places.

Dose adjustments

Renal

UK SPC section 4.2: 'In patients with renal impairment dose should be reduced.' No figure is given. Section 4.4: measure plasma potassium at regular intervals, especially in patients with renal impairment; care in decreased renal function (renal insufficiency) and post-operative oliguria; elderly patients need close monitoring because renal function may be impaired.

Hepatic

The UK SPC gives no dose adjustment or specific caution for hepatic impairment.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via MHRA Products — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hyperkalaemia (section 4.3 - the only contraindication listed)

Side effects

  • Excessive intake of potassium may cause hyperkalaemia, which may cause neuromuscular and cardiac disorders, especially arrhythmias, and even cardiac arrest (section 4.8)
  • Acidosis, hyperchloraemia (section 4.8)
  • Venous thrombosis; phlebitis in case of too high local concentrations (section 4.8)
  • Nausea; pain on injection; necrosis in case of extravasation (section 4.8)
  • Direct injection of undiluted concentrate may cause instant death (section 4.4)

Interactions

  • Potassium-sparing diuretics (amiloride, spironolactone, triamterene, potassium canrenoate, eplerenone): combination not recommended except in severe hypokalaemia; risk of potentially lethal hyperkalaemia, particularly in renal impairment (section 4.5)
  • ACE inhibitors, angiotensin II receptor antagonists, NSAIDs, ciclosporin, tacrolimus, suxamethonium: potentially lethal hyperkalaemia, particularly in renal insufficiency; combination not recommended except in severe hypokalaemia (section 4.5)
  • Blood products, potassium salts of penicillin: potential risk of hyperkalaemia from the potassium they contain; combination not recommended except in severe hypokalaemia (section 4.5)
  • Quinidine: potassium can increase its anti-arrhythmic effects (section 4.5)
  • Thiazides, adrenocorticoids, glucocorticoids, mineralocorticoids: the effects of the potassium supplement may be decreased (section 4.5)
  • Digoxin: hyperkalaemia can be dangerous in digitalised patients (section 4.5)
  • Exchange resins: serum potassium levels are reduced by sodium replacement of the potassium (section 4.5)

Monitoring

  • Serum electrolyte levels and acid-base status; adjust the dose to the needs of the patient (section 4.4)
  • Plasma potassium concentration at regular intervals during treatment to avoid hyperkalaemia, especially in renal impairment and other conditions often related to hyperkalaemia (section 4.4)
  • Urine flow: adequate urine flow must be ensured and monitored (section 4.4)
  • ECG monitoring facilities should be available and patients frequently monitored; continuous ECG monitoring is advisable when higher concentrations are used for severe hypokalaemia or diabetic ketoacidosis (sections 4.2, 4.4)
  • Care with uncompensated cardiac insufficiency, digitalis treatment, severe or complete heart block, adrenal insufficiency, post-operative oliguria, shock with haemolytic reactions and/or dehydration, metabolic acidosis, potassium-sparing diuretics, acute dehydration, heat cramps and extensive tissue destruction such as severe burns (section 4.4)
  • Infusion site: watch for extravasation, which can cause necrotic tissue damage (section 4.4)

Clinical monograph

How it works

It replaces the potassium ion, the principal intracellular cation essential for resting membrane potential, neuromuscular conduction and cardiac rhythm, correcting the consequences of potassium depletion.

Prescribing in practice

  • Concentrated potassium chloride is a high-risk medicine that must always be diluted and given as a controlled-rate infusion, never as a bolus or rapid push, because inadvertent rapid administration can cause fatal cardiac arrest.
  • Use ready-diluted preparations where possible and infuse faster or more concentrated solutions only with continuous cardiac monitoring, ideally via a central line for stronger concentrations.
  • Caution is required in renal impairment and when co-prescribed with potassium-retaining drugs such as ACE inhibitors, ARBs and potassium-sparing diuretics, given the risk of hyperkalaemia.

Monitoring

Monitor serum potassium and renal function regularly, with ECG/cardiac monitoring during higher-rate or more concentrated infusions.

Counselling the patient

  • This is a potassium replacement given slowly through a drip to correct a low blood level.
  • It is always diluted and never given quickly because of the risk to the heart.
  • Pain or stinging at the drip site should be reported, as the solution can irritate the vein.

Evidence & guidelines

Concentrated potassium chloride is recognised as a high-alert medicine, and UK patient-safety guidance (NPSA) mandates restricted storage and controlled dilution and infusion to prevent fatal medication errors.

Reference: NPSA Patient Safety Alert 2002 (Potassium Chloride); ICU electrolyte replacement protocols; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators
Pathways