What are the contraindications and precautions for using Furosemide (Lasix) in patients with various medical conditions, including hypersensitivity, anuria, severe renal impairment, hepatic cirrhosis, kidney disease, electrolyte imbalances, and geriatric or dementia patients?

Furosemide Contraindications

Furosemide is absolutely contraindicated in patients with anuria and those with a history of hypersensitivity to furosemide. 1

Absolute Contraindications

Anuria

• Furosemide must never be administered to patients with anuria, as the drug requires urinary excretion to reach its site of action in the loop of Henle and cannot be effective without urine production 2, 1
• This represents a fundamental pharmacologic limitation—the drug cannot work if the kidneys are not producing urine 2

Hypersensitivity

• Patients with documented hypersensitivity to furosemide are absolutely contraindicated from receiving the medication 1
• Patients allergic to sulfonamides may also be allergic to furosemide and should be evaluated carefully before administration 1

Severe Electrolyte Disturbances

• Severe hyponatremia (serum sodium <120-125 mmol/L) is an absolute contraindication requiring immediate discontinuation of all diuretics 3, 2
• Severe hypokalemia (<3.0 mmol/L) mandates stopping furosemide, though aldosterone antagonists may be continued 3, 2
• In cirrhotic patients specifically, diuretics should be discontinued if serum sodium falls below 125 mmol/L 4

Relative Contraindications and High-Risk Situations

Hepatic Cirrhosis with Complications

• Overt or worsening hepatic encephalopathy in cirrhotic patients is generally a contraindication to diuretic therapy, as furosemide can precipitate or worsen encephalopathy 2
• Diuretics should be used with extreme caution in cirrhotic patients with renal impairment, hyponatremia, or potassium disturbances 2
• The combination of furosemide with spironolactone in a 40:100 mg ratio is preferred in cirrhosis to minimize electrolyte disturbances 3

Severe Renal Impairment

• While not an absolute contraindication, progressive renal failure or acute kidney injury requires immediate discontinuation 2
• Caution is required when starting furosemide in patients with renal impairment, though no specific creatinine threshold is definitively established 2
• In patients with chronic renal insufficiency, furosemide elimination half-life is significantly prolonged (200 minutes vs. 51 minutes in healthy subjects), requiring dose adjustments 5

Marked Hypovolemia and Hypotension

• Furosemide should never be used expecting it to improve hemodynamics in hypotensive patients—it will worsen tissue perfusion and precipitate cardiogenic shock 2
• Marked hypovolemia or hypotension (systolic BP <90 mmHg) without circulatory support is a contraindication to furosemide administration 6, 2
• Excessive diuresis may cause dehydration and blood volume reduction with circulatory collapse and possibly vascular thrombosis and embolism, particularly in elderly patients 1

Special Population Precautions

Elderly and Geriatric Patients

• Elderly patients are at particularly high risk for excessive diuresis causing dehydration, blood volume reduction, circulatory collapse, and vascular thrombosis 1
• These patients require more careful monitoring and often lower initial doses 1

Patients with Diabetes Mellitus

• Furosemide may increase blood glucose levels and precipitate diabetes mellitus, requiring careful monitoring 2, 1
• Patients with diabetes should be told that furosemide may increase blood glucose levels and affect urine glucose tests 1

Patients with Urinary Retention

• In patients with severe symptoms of urinary retention (bladder emptying disorders, prostatic hyperplasia, urethral narrowing), furosemide can cause acute urinary retention related to increased urine production 1
• These patients require careful monitoring, especially during initial treatment stages 1

Patients Receiving Radiocontrast

• In patients at high risk for radiocontrast nephropathy, furosemide can lead to higher incidence of deterioration in renal function compared to patients receiving only intravenous hydration 1

Patients with Hypoproteinemia

• In patients with hypoproteinemia (e.g., nephrotic syndrome), the effect of furosemide may be weakened and its ototoxicity potentiated 1

Critical Monitoring Requirements

Electrolyte Monitoring

• All patients receiving furosemide should be observed for signs of fluid or electrolyte imbalance: hyponatremia, hypochloremic alkalosis, hypokalemia, hypomagnesemia, or hypocalcemia 1
• Clinical signs include dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, arrhythmia, or gastrointestinal disturbances 1
• Serum electrolytes (particularly potassium), CO2, creatinine, and BUN should be determined frequently during the first few months of therapy and periodically thereafter 1

Hypokalemia Management

• Hypokalemia may develop with furosemide, especially with brisk diuresis, inadequate oral electrolyte intake, cirrhosis, or concomitant use of corticosteroids, ACTH, or prolonged laxative use 1
• Digitalis therapy may exaggerate metabolic effects of hypokalemia, especially myocardial effects 1
• Potassium supplements and/or dietary measures may be needed to control or avoid hypokalemia 1

Renal Function Monitoring

• Reversible elevations of BUN may occur and are associated with dehydration, which should be avoided, particularly in patients with renal insufficiency 1
• Abnormalities should be corrected or the drug temporarily withdrawn 1

Drug Interactions and Combination Therapy Concerns

Combination with Other Diuretics

• The combination of metolazone and furosemide can cause severe electrolyte disturbances with a pattern of hyponatremia, disproportionate hypochloremia, alkalosis, and hypokalemia 7
• This combination should be used with extreme caution due to potential severe untoward effects 7

Digitalis Therapy

• Digitalis therapy may exaggerate metabolic effects of hypokalemia, especially myocardial effects, requiring careful potassium monitoring 1

Common Pitfalls to Avoid

• Never escalate furosemide beyond 160 mg/day in cirrhosis—this indicates diuretic resistance requiring alternative strategies like large-volume paracentesis 2
• Do not use furosemide to prevent or treat acute kidney injury itself—only use it to manage volume overload that complicates AKI 6
• Avoid administering furosemide in hypotensive patients expecting hemodynamic improvement—it will worsen perfusion 2
• Never ignore developing electrolyte abnormalities—they can progress to life-threatening complications 1, 7
• Do not overlook the need for potassium supplementation, especially in patients on digitalis or with cardiac disease 1

Additional Safety Considerations

• Patients should be observed regularly for possible blood dyscrasias, liver or kidney damage, or other idiosyncratic reactions 1
• The possibility exists of exacerbation or activation of systemic lupus erythematosus 1
• Asymptomatic hyperuricemia can occur and gout may rarely be precipitated 1
• The skin of some patients may be more sensitive to sunlight while taking furosemide 1
• Hypertensive patients should avoid medications that may increase blood pressure, including over-the-counter products for appetite suppression and cold symptoms 1