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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat edema associated with heart failure, liver disease, and renal disease, as well as hypertension.
## Primary Indications
* Edema (heart failure, cirrhosis, renal disease)
* Hypertension
## Adult Dosing
* **Edema:**
* Oral: Start with 20-80 mg once daily. May increase by 20-40 mg every 6-8 hours as needed. Doses can be given once daily, twice daily, or divided.
* Intravenous (IV)/Intramuscular (IM): Start with 20-40 mg once daily. May increase by 20 mg every 2 hours as needed.
* Maximum dose: Oral 600 mg/day; IV/IM 200 mg/day. Higher doses may be used in severe, refractory cases under close monitoring, but efficacy and safety at very high doses are less established.
* **Hypertension (adjunctive therapy):**
* Oral: 40 mg twice daily.
## Pediatric Dosing
* **Edema:**
* Oral: 1-4 mg/kg/day in 1-2 divided doses.
* IV/IM: 1 mg/kg/dose. May increase by 1 mg/kg every 2 hours as needed.
* Maximum dose: Oral 6 mg/kg/day; IV/IM 20 mg/dose.
## Dose Adjustments
* **Renal Impairment:** Increased sensitivity may occur. Monitor electrolytes and renal function closely. Doses may need to be reduced.
* **Hepatic Impairment:** May require dose reduction due to altered metabolism and increased risk of electrolyte imbalances.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides
## Adverse Effects
* Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia)
* Dehydration
* Ototoxicity (especially with rapid IV administration or high doses)
* Hypotension
* Hyperuricemia, hyperglycemia
* Dizziness, lightheadedness
* Nausea, vomiting
## Key Drug Interactions
* **Aminoglycosides, other ototoxic drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effect; increase risk of renal toxicity.
* **Digoxin:** Risk of toxicity increased by furosemide-induced hypokalemia.
* **Antihypertensives:** Additive hypotensive effects.
* **Lithium:** May reduce renal clearance, increasing lithium levels and risk of toxicity.
* **Corticosteroids:** Increased risk of hypokalemia.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Fluid status (weight, intake/output)
* Blood pressure
* Hearing (especially with high doses or risk factors)
## Clinical Pearls
* Administer oral furosemide preferably on an empty stomach to enhance absorption, but may be given with food or milk if GI upset occurs.
* IV administration should be slow (over 30-60 minutes) to minimize ototoxicity. Avoid rapid IV bolus.
* Significant diuresis can occur rapidly. Monitor patients for signs of dehydration and electrolyte depletion.
* In patients with heart failure, a lower starting dose and slower titration may be preferred.
* The need for dose adjustment in renal impairment depends on the degree of impairment and patient response.
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*This information is intended for healthcare professionals. Always consult the official prescribing information and relevant clinical guidelines before making therapeutic decisions.*
