Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
LASIX vs ETHACRYNIC ACID
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Furosemide inhibits the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle, reducing sodium, chloride, and water reabsorption and increasing urinary output.
Inhibits sodium-potassium-chloride cotransporter (NKCC2) in the thick ascending limb of the loop of Henle, leading to increased excretion of sodium, chloride, potassium, and water. Also inhibits prostaglandin degradation.
Edema associated with congestive heart failure, cirrhosis of the liver, and renal disease including nephrotic syndrome,Hypertension (off-label)
Treatment of edema associated with congestive heart failure, cirrhosis, and renal disease,Treatment of ascites,Treatment of hypertension (off-label),Adjunctive therapy in acute pulmonary edema (off-label)
20-80 mg IV or PO once or twice daily; maximum 600 mg/day IV or PO.
50 to 100 mg orally once daily; may increase by 25 to 50 mg increments at intervals of 2 to 3 days up to 400 mg/day. IV: 0.5 to 1 mg/kg slowly (over several minutes); usual initial dose 50 mg.
Terminal elimination half-life is approximately 1.5-2 hours. In renal impairment (Cr Cl <20 m L/min), half-life may prolong to up to 2-4 hours; in end-stage renal disease or heart failure, may exceed 4 hours.
Terminal elimination half-life is approximately 2-4 hours in patients with normal renal function; may be prolonged in renal impairment.
Furosemide is metabolized primarily by glucuronidation via UGT1A1, with minimal hepatic metabolism; about 50% is excreted unchanged in urine.
Primarily metabolized by conjugation with glutathione; also undergoes hepatic metabolism via CYP450 enzymes (minor).
Primarily renal excretion (50-80% as unchanged drug) via glomerular filtration and proximal tubular secretion; minor fecal elimination (<5%).
Primarily renal (approximately 60-70% as unchanged drug and metabolites) with some biliary/fecal excretion (approximately 30-40%).
91-99% bound, primarily to albumin.
Approximately 90-98% bound to plasma proteins, primarily albumin.
0.1-0.2 L/kg in healthy adults; increases in conditions with reduced plasma protein binding (e.g., nephrotic syndrome) or fluid overload (e.g., heart failure) up to 0.3-0.8 L/kg.
Volume of distribution is approximately 0.1-0.2 L/kg, indicating limited extravascular distribution.
Oral: 60-70% (range 50-80%); decreased by food; intravenous: 100%.
Oral bioavailability is approximately 100%.
GFR 10-50 m L/min: dose every 12 hours; GFR <10 m L/min: avoid use or use with extreme caution.
e GFR 30-59 m L/min: no adjustment; e GFR <30 m L/min: avoid use due to risk of ototoxicity and decreased efficacy.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated or avoid.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use.
1-2 mg/kg/dose PO or IV every 6-12 hours; maximum 6 mg/kg/day.
Oral: 1 mg/kg/dose once daily; may increase by 1 mg/kg/dose at intervals of 2-3 days up to 3 mg/kg/day. IV: 1 mg/kg/dose slow IV; maximum 50 mg/dose.
Start at 20 mg/day PO or 20 mg IV, titrate slowly due to increased sensitivity and risk of electrolyte disturbances.
Initiate at lower doses (25 mg orally once daily) due to increased risk of electrolyte disturbances and renal impairment; monitor closely.
Furosemide is a potent diuretic. If given in excessive amounts, it can lead to profound diuresis with water and electrolyte depletion. Therefore, careful medical supervision is required, and dose and dose schedule must be adjusted to the individual patient's needs.
This drug is a potent diuretic which, if given in excessive amounts, can lead to profound diuresis with water and electrolyte depletion. Close medical supervision and dose adjustment are required.
Risk of hypovolemia, dehydration, and electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia),Ototoxicity, especially with rapid injection or severe renal impairment,Sulfonamide cross-sensitivity
Risk of excessive diuresis leading to dehydration, electrolyte imbalance, and hypovolemia,May cause ototoxicity, especially with rapid IV administration or in patients with renal impairment,Can worsen azotemia or precipitate hepatic encephalopathy in cirrhotic patients,Monitor serum electrolytes, CO2, BUN, and creatinine regularly,Use with caution in patients with diabetes mellitus (may increase blood glucose),May cause hyperuricemia and gout
Anuria,History of hypersensitivity to furosemide or sulfonamides
Anuria,Hypersensitivity to ethacrynic acid or any component of the formulation,Severe electrolyte depletion (hypokalemia, hyponatremia) until corrected,Concurrent use with other ototoxic drugs (e.g., aminoglycosides) may increase risk
High sodium intake can counteract diuretic effects. Avoid excessive licorice consumption as it can worsen hypokalemia. Grapefruit juice may increase systemic exposure of furosemide; avoid concurrent use.
Avoid licorice, which can worsen hypokalemia. Limit salt intake as directed. No specific food interactions; maintain a balanced diet.
Furosemide crosses the placenta. First trimester: limited data, no clear teratogenic pattern; risk cannot be excluded. Second and third trimesters: may cause maternal hypovolemia, decreased placental perfusion, electrolyte imbalances, and fetal dehydration; oligohydramnios reported. Use only if clearly needed.
First trimester: Limited human data; animal studies show no teratogenicity but fetal toxicity at high doses. Second trimester: Theoretical risk of electrolyte imbalances affecting fetal development. Third trimester: Risk of premature ductus arteriosus closure due to prostaglandin inhibition (theoretical), neonatal ototoxicity, and thrombocytopenia.
Furosemide is excreted into breast milk in low amounts. M/P ratio approximately 1:1. No adverse effects reported in infants, but may suppress lactation. Use with caution, especially in neonates.
Safety not established. Drug excreted in breast milk; M/P ratio unknown. Avoid breastfeeding or use with caution due to potential for ototoxicity and electrolyte disturbances in the infant.
Pregnancy may increase volume of distribution and renal clearance, potentially reducing furosemide exposure. Dose adjustments may be necessary to maintain efficacy; titration based on clinical response and monitoring recommended. No established dose modification guidelines; individualize therapy.
No standard dose adjustment; use lowest effective dose. Monitor for hypokalemia and volume depletion, which may be more pronounced in pregnancy. Consider adjusting dose based on maternal weight and renal function.
For rapid diuresis in acute pulmonary edema, administer IV furosemide slowly over 1-2 minutes to avoid ototoxicity. Monitor serum potassium closely, especially in patients on digoxin or with hepatic cirrhosis. Higher doses (>80 mg) may require divided doses to prevent peak-related adverse effects.
Ethacrynic acid is a loop diuretic used for patients with sulfonamide allergy, as it is not a sulfonamide derivative. Monitor for ototoxicity, especially when given with aminoglycosides or in renal impairment. Rapid diuresis may cause hypokalemia, hypomagnesemia, and metabolic alkalosis. Use cautiously in hepatic cirrhosis to avoid electrolyte-induced coma.
Take furosemide exactly as prescribed, usually in the morning to avoid nighttime urination.,Weigh yourself daily and report rapid weight gain or loss of more than 2-3 pounds in a day.,Avoid prolonged sun exposure and use sunscreen as furosemide can increase sun sensitivity.,Do not stop taking this medication abruptly; tapering may be needed to avoid rebound fluid retention.
Take exactly as prescribed, usually once or twice daily.,Expect increased urination; take in the morning to avoid nighttime trips.,Weigh yourself daily and report rapid weight gain or loss.,Avoid alcohol and medications that may cause dizziness.,This drug may cause hearing loss or ringing in the ears; report immediately.,Do not take with aspirin or other NSAIDs without doctor approval.,Inform your doctor if you have gout, diabetes, or kidney disease.,Stay adequately hydrated but avoid excessive fluid intake.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about LASIX vs ETHACRYNIC ACID, answered by our medical review team.
LASIX is a Loop Diuretic that works by Furosemide inhibits the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle, reducing sodium, chloride, and water reabsorption and increasing urinary output.. ETHACRYNIC ACID is a Loop Diuretic that works by Inhibits sodium-potassium-chloride cotransporter (NKCC2) in the thick ascending limb of the loop of Henle, leading to increased excretion of sodium, chloride, potassium, and water. Also inhibits prostaglandin degradation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between LASIX and ETHACRYNIC ACID depend on the specific clinical indication. These are both Loop Diuretic agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of LASIX is: 20-80 mg IV or PO once or twice daily; maximum 600 mg/day IV or PO.. The standard adult dose of ETHACRYNIC ACID is: 50 to 100 mg orally once daily; may increase by 25 to 50 mg increments at intervals of 2 to 3 days up to 400 mg/day. IV: 0.5 to 1 mg/kg slowly (over several minutes); usual initial dose 50 mg.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between LASIX and ETHACRYNIC ACID in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. LASIX is classified as Category C. Furosemide crosses the placenta. First trimester: limited data, no clear teratogenic pattern; risk cannot be excluded. Second and third trimesters: may cause maternal hypovolemia, . ETHACRYNIC ACID is classified as Category C. First trimester: Limited human data; animal studies show no teratogenicity but fetal toxicity at high doses. Second trimester: Theoretical risk of electrolyte imbalances affecting . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.