What is the maximum oral dose of Lasix (furosemide) per day?

Maximum Oral Dose of Furosemide

The maximum oral dose of furosemide is 600 mg/day according to the FDA label, though this should be carefully titrated in patients with clinically severe edematous states. 1

Standard Maximum Doses by Clinical Indication

Cirrhosis with Ascites

• The maximum recommended dose is 160 mg/day in cirrhotic patients, typically combined with spironolactone 2, 3
• Starting dose is 40 mg orally as a single morning dose, combined with spironolactone 100 mg 2, 3
• Doses should be increased in 40 mg steps every 72 hours if inadequate response 2
• Exceeding 160 mg/day in cirrhosis is considered a marker of diuretic resistance and indicates need for alternative strategies such as large volume paracentesis 2, 3

Heart Failure and General Edema

• The usual initial dose is 20-80 mg given as a single dose 1
• The dose may be raised by 20-40 mg increments, given no sooner than 6-8 hours after the previous dose 1
• For clinically severe edematous states, doses may be carefully titrated up to 600 mg/day 1
• Doses above 160 mg/day in heart failure indicate need for treatment escalation with combination therapy or alternative strategies 3

Pediatric Patients

• The usual initial dose is 2 mg/kg body weight as a single dose 1
• Dosage may be increased by 1-2 mg/kg no sooner than 6-8 hours after the previous dose 1
• Doses greater than 6 mg/kg body weight are not recommended 1
• For severe edema in nephrotic syndrome, doses up to 10 mg/kg per day may be used (divided into multiple doses), but high doses >6 mg/kg/day should not be given for periods longer than 1 week 3

Critical Monitoring Requirements at High Doses

When Doses Exceed 80 mg/day

• Careful clinical observation and laboratory monitoring are particularly advisable 1
• Regular monitoring of serum sodium, potassium, and creatinine is essential 2, 3
• Monitor for signs of hypovolemia: decreased skin turgor, hypotension, tachycardia 3
• Assess urine output and kidney function (estimated glomerular filtration rate) 3

Absolute Contraindications to Dose Escalation

• Severe hyponatremia (serum sodium <120-125 mmol/L) - diuretics should be discontinued 2, 3
• Severe hypokalemia (<3 mmol/L) - furosemide should be stopped 2
• Progressive renal failure or acute kidney injury 2, 3
• Marked hypotension (systolic BP <90 mmHg) without circulatory support 3
• Anuria 2, 3
• Worsening hepatic encephalopathy or incapacitating muscle cramps 2, 3

Important Caveats and Clinical Pitfalls

Diuretic Resistance

• When standard doses fail, combination therapy is preferred over escalating furosemide alone 3
• Consider adding thiazides (hydrochlorothiazide 25 mg) or aldosterone antagonists (spironolactone 25-50 mg) 2, 3
• In cirrhosis specifically, exceeding 160 mg/day signals need for large volume paracentesis rather than further dose escalation 2, 3

Special Populations

• Geriatric patients should start at the low end of the dosing range with cautious titration 1
• In cirrhosis, oral administration is preferred over IV due to good bioavailability and avoidance of acute GFR reductions 3
• Target weight loss should not exceed 0.5 kg/day in patients without peripheral edema and 1 kg/day in those with edema 2, 3

Historical Context

• While research studies have documented safe use of furosemide at doses up to 8 g/day in severe cardiac failure 4 and up to 2 g/day in hemodialysis patients 5, 6, these extreme doses are not part of standard clinical practice and the FDA-approved maximum remains 600 mg/day 1