What is the recommended dosage of furosemide (Lasix) for an adult patient?

Furosemide Adult Dosing

For adults with edema, start with furosemide 20-40 mg orally once daily in the morning, which can be increased by 20-40 mg increments every 6-8 hours until adequate diuresis is achieved, with careful titration up to 600 mg/day in severe edematous states. 1

Initial Dosing by Clinical Context

Acute Heart Failure with Pulmonary Edema

• Administer 20-40 mg IV bolus over 1-2 minutes as the initial dose 2
• For patients already on chronic oral furosemide >40 mg/day at home, start with 80 mg IV rather than 40 mg 2
• Total furosemide dose should remain <100 mg in the first 6 hours and <240 mg during the first 24 hours 2
• Do not administer if systolic blood pressure <90-100 mmHg without circulatory support—furosemide will worsen hypoperfusion and precipitate cardiogenic shock 2

Chronic Heart Failure with Volume Overload

• Start with 20-40 mg orally once daily in the morning 1
• If inadequate response after 24 hours (no weight loss of 0.5-1.0 kg), increase by 20-40 mg 1
• Doses exceeding 160 mg/day indicate advanced disease requiring treatment escalation beyond diuretics alone 2

Cirrhosis with Ascites

• Start with furosemide 40 mg combined with spironolactone 100 mg as a single morning dose 2
• Maintain the 100:40 spironolactone-to-furosemide ratio when escalating 2
• Increase both drugs simultaneously every 3-5 days if weight loss <0.5 kg/day (without peripheral edema) or <1.0 kg/day (with peripheral edema) 2
• Maximum dose is 160 mg/day—exceeding this indicates diuretic resistance requiring large-volume paracentesis rather than further escalation 2
• Oral administration is preferred over IV to avoid acute GFR reduction 2

Nephrotic Syndrome with Severe Edema

• Start with 0.5-2 mg/kg per dose IV or orally up to six times daily (maximum 10 mg/kg per day) 2
• High doses >6 mg/kg/day should not be given for periods longer than 1 week 2
• Infusions should be administered over 5-30 minutes to avoid ototoxicity 2

Dose Escalation Strategy

Standard Oral Titration

• The usual initial dose is 20-80 mg as a single dose 1
• If needed, administer the same dose 6-8 hours later or increase the dose 1
• Raise by 20-40 mg increments, given no sooner than 6-8 hours after the previous dose 1
• Once the desired effect is achieved, give the individually determined single dose once or twice daily (e.g., 8 AM and 2 PM) 1

High-Dose Therapy for Refractory Cases

• Doses may be carefully titrated up to 600 mg/day in patients with clinically severe edematous states 1
• When doses exceed 80 mg/day for prolonged periods, careful clinical observation and laboratory monitoring are particularly advisable 1
• Research evidence supports doses up to 500-2000 mg/day in refractory cardiac failure, though this exceeds typical guideline recommendations 3, 4
• Doses of 250 mg and above must be given by infusion over 4 hours to prevent ototoxicity 2

Route of Administration

Oral vs. Intravenous

• IV administration is preferred in acute situations requiring rapid diuresis 2
• Oral administration is preferred in cirrhotic patients due to good bioavailability and avoidance of acute GFR reductions 2
• Gut wall edema in heart failure reduces oral bioavailability, making IV route more reliable in acute decompensation 2

IV Bolus vs. Continuous Infusion

• IV bolus: 20-40 mg over 1-2 minutes for initial dose 2
• Continuous infusion: 5-10 mg/hour (maximum rate 4 mg/min) may be considered after initial bolus in patients with volume overload 2
• Continuous infusion is preferred over repeated boluses for patients requiring ≥120 mg or higher doses 2

Critical Monitoring Requirements

Before Administration

• Verify systolic blood pressure ≥90-100 mmHg 2
• Exclude marked hypovolemia, severe hyponatremia (<120-125 mmol/L), or anuria 2
• Check baseline electrolytes (sodium, potassium) and renal function (creatinine, BUN) 2

During Treatment

• Monitor urine output hourly in acute settings (place bladder catheter) 2
• Check blood pressure every 15-30 minutes in the first 2 hours after IV administration 2
• Target weight loss: 0.5 kg/day without peripheral edema, 1.0 kg/day with peripheral edema 2
• Monitor electrolytes every 3-7 days during initial titration, then weekly 2

Absolute Contraindications to Continuation

• Stop furosemide immediately if: 2
  • Severe hyponatremia (serum sodium <120-125 mmol/L)
  • Severe hypokalemia (<3 mmol/L)
  • Progressive renal failure or acute kidney injury
  • Anuria develops
  • Marked hypotension (SBP <90 mmHg) without circulatory support
  • Worsening hepatic encephalopathy (in cirrhosis)

Management of Diuretic Resistance

Sequential Nephron Blockade

• Add thiazide diuretic (hydrochlorothiazide 25 mg PO) or aldosterone antagonist (spironolactone 25-50 mg PO) rather than escalating furosemide alone 2
• This combination is more effective than monotherapy escalation when no response occurs after reaching high doses 2
• In nephrotic syndrome, use amiloride instead of spironolactone when potassium-sparing diuretics are needed 2

Alternative Strategies

• Consider continuous infusion after initial bolus 2
• In cirrhosis exceeding 160 mg/day, proceed to large-volume paracentesis rather than further dose escalation 2
• For pulmonary edema refractory to 500 mg, consider IV dopamine 2.5 μg/kg/min to enhance diuresis or venovenous isolated ultrafiltration 2

Special Populations

Geriatric Patients

• Start at the low end of the dosing range 1
• Use cautious dose selection and adjustment 1
• Morning dosing improves adherence and reduces nighttime urination 2

Pediatric Patients

• Usual initial dose: 2 mg/kg body weight as a single dose 1
• If inadequate response, increase by 1-2 mg/kg no sooner than 6-8 hours after previous dose 1
• Doses >6 mg/kg body weight are not recommended 1
• For maintenance, adjust to minimum effective level 1

Common Pitfalls to Avoid

• Never give furosemide to hypotensive patients expecting it to improve hemodynamics—it causes further volume depletion and worsens tissue perfusion 2
• Avoid evening doses—they cause nocturia and poor adherence without improving outcomes 2
• Do not use furosemide as monotherapy in acute pulmonary edema—concurrent IV nitroglycerin is superior and should be started simultaneously 2
• Avoid initiating furosemide in patients with pulmonary edema but low blood pressure without first providing circulatory support 2
• Do not use furosemide to prevent or treat acute kidney injury itself—only use it to manage volume overload that complicates AKI 2
• Exceeding target weight loss (>0.5-1.0 kg/day) increases risk of intravascular volume depletion and renal failure 2