Lasix (Furosemide)

Lasix (furosemide) is employed in the management of fluid overload conditions and related cardiovascular disorders.

• Congestive heart failure: reduces pulmonary and peripheral edema, improving breathing and exercise tolerance.
• Hypertension: lowers elevated blood pressure by decreasing plasma volume.
• Renal disease–related edema: facilitates removal of excess fluid in patients with chronic kidney disease.
• Liver cirrhosis: alleviates ascites and peripheral edema associated with portal hypertension.
• Pulmonary edema: rapidly decreases fluid accumulation in the lungs, aiding oxygenation.

• Furosemide acts on the thick ascending limb of the loop of Henle by blocking the Na⁺‑K⁺‑2Cl⁻ cotransporter. This inhibition prevents reabsorption of sodium, potassium and chloride, creating an osmotic gradient that retains water in the tubular lumen. The resulting diuresis leads to increased urinary output of sodium, chloride and water, thereby reducing extracellular fluid volume and blood pressure.

Furosemide may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Increased urination: frequent or larger volume of urine.
• Electrolyte imbalance: low potassium, sodium or magnesium levels.
• Dizziness or light‑headedness: especially when standing quickly.
• Dehydration: dry mouth, thirst, or reduced skin turgor.
• Headache: mild to moderate intensity.

Serious or Rare Side Effects

• Severe electrolyte disturbances: hypokalemia or hyponatremia leading to cardiac arrhythmias.
• Acute kidney injury: sudden decline in renal function.
• Ototoxicity: hearing loss or ringing in the ears, particularly with high doses.
• Allergic reactions: rash, itching, swelling or anaphylaxis.
• Hyperuricemia: gout flare due to elevated uric acid.

When prescribing or dispensing Lasix, several safety considerations should be observed to minimize risk.

• Monitor electrolytes: check serum potassium, sodium and magnesium regularly.
• Assess renal function: evaluate creatinine and eGFR before initiation and during therapy.
• Adjust dose in the elderly: start with lower doses due to increased sensitivity.
• Caution in pregnancy: category B1, use only if benefit outweighs potential risk.
• Avoid concurrent ototoxic drugs: limit use with aminoglycosides or other loop diuretics.
• Store at ambient temperature: keep below 25 °C in the original container, protect from moisture.

Furosemide can interact with other medicines, altering its efficacy or increasing toxicity.

Major Interactions (Avoid)

• Aminoglycoside antibiotics: may enhance ototoxicity.
• NSAIDs (e.g., ibuprofen, naproxen): can reduce diuretic response.
• Lithium: increased lithium levels and risk of toxicity.
• Antihypertensive agents: additive blood pressure lowering, risk of hypotension.
• Cisplatin: heightened nephrotoxicity.

Moderate Interactions (Monitor Closely)

• ACE inhibitors or ARBs: may cause excessive potassium loss.
• Digoxin: risk of digitalis toxicity with electrolyte disturbances.
• Corticosteroids: may worsen fluid and electrolyte imbalance.
• Antidiabetic drugs: potential hypoglycemia due to altered glucose handling.
• Warfarin: possible alteration in INR, monitor coagulation.