Lasix (Furosemide)

• Furosemide acts on the renal loop of Henle to reduce fluid overload in several cardiovascular and hepatic conditions.
• Edema associated with congestive heart failure, liver cirrhosis, or renal disease: reduces excess fluid accumulation and improves symptoms.
• Hypertension: lowers blood pressure by promoting sodium and water excretion.
• Acute pulmonary edema: rapidly decreases pulmonary fluid volume to improve breathing.

• Furosemide inhibits the Na⁺‑K⁺‑2Cl⁻ symporter located in the thick ascending limb of the loop of Henle. By blocking this transporter, it prevents reabsorption of sodium, chloride, and potassium, leading to increased urinary excretion of these ions together with water. The resulting diuresis reduces intravascular volume and decreases preload and afterload on the heart. The diuretic effect also promotes a modest reduction in systemic vascular resistance, contributing to its antihypertensive action.

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

Common Side Effects

• Increased urination: frequent and large‑volume urine output.
• Thirst or dry mouth: sensation of dehydration.
• Electrolyte imbalance (especially low potassium): mild hypokalemia symptoms.
• Dizziness or light‑headedness: due to reduced blood pressure.

Serious or Rare Side Effects

• Severe dehydration or electrolyte disturbances: can lead to arrhythmias.
• Ototoxicity: hearing loss or ringing in the ears, especially with high doses.
• Allergic reactions: rash, itching, swelling, or anaphylaxis.

Before initiating furosemide therapy, several safety considerations should be reviewed.

• Monitor electrolytes: check serum potassium, sodium, and magnesium regularly.
• Assess renal function: evaluate creatinine and eGFR before and during treatment.
• Adjust dose in hepatic impairment: use lower doses in patients with liver disease.
• Avoid concurrent nephrotoxic drugs: limit use of NSAIDs or aminoglycosides.
• Caution in diabetes: monitor blood glucose as diuresis may affect levels.
• Store at room temperature: keep in original packaging, protect from moisture and heat.

Furosemide can interact with several medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• NSAIDs: may blunt diuretic response and increase renal risk.
• Aminoglycoside antibiotics: combined use can heighten nephrotoxicity.
• Lithium: furosemide reduces lithium clearance, raising toxicity risk.

Moderate Interactions (Monitor Closely)

• ACE inhibitors or ARBs: may enhance hypotensive effect and affect kidney function.
• Digoxin: electrolyte changes from furosemide can predispose to digoxin toxicity.