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Loop Diuretic

Furosemide (IV — ICU)

Brand names: Lasix

Used in: Heart Failure Chronic Kidney Disease Liver Disease & Cirrhosis Acute Kidney Injury

Furosemide is a loop diuretic used to relieve fluid overload in acute pulmonary oedema and decompensated heart failure, and in other oedematous states; the intravenous route is used when rapid effect or poor gut absorption is a concern.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION Edema Therapy should be individualized according to patient response to gain maximal therapeutic response and to determine the minimal dose needed to maintain that response. Adults: The usual initial dose of furosemide tablets is 20 to 80 mg given as a single dose. Ordinarily a prompt diuresis ensues. If needed, the same dose can be administered 6 to 8 hours later or the dose may be increased. The dose may be raised by 20 or 40 mg and given not sooner than 6 to 8 hours after the previous dose until the desired diuretic effect has been obtained. The individually determined single dose should then be given once or twice daily (e.g., at 8 am and 2 pm). The dose of …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2023-03-01. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

Furosemide inhibits the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle, producing a powerful diuresis with loss of sodium, potassium and other electrolytes.

Prescribing in practice

  • Give intravenous doses slowly; rapid administration of high doses risks ototoxicity, especially in renal impairment.
  • Monitor fluid balance and electrolytes — hypokalaemia, hyponatraemia and worsening renal function can occur.
  • Effect may be blunted in significant renal impairment, sometimes needing higher doses or an infusion.

Monitoring

Monitor U&E (sodium, potassium, renal function), fluid balance, weight and blood pressure; watch for over-diuresis.

Counselling the patient

  • It increases how much you pass urine, so timing of oral doses matters for daily routine.
  • Report dizziness, cramps, or marked thirst.

Evidence & guidelines

Loop diuretics are first-line for congestion in acute heart failure (NICE NG106); they relieve symptoms but are titrated to clinical response.

Reference: DOSE Trial (Felker et al, NEJM 2011); ESC Heart Failure Guidelines 2021; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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