furosemide (Rx)

Brand and Other Names:Lasix
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Dosing & Uses


Dosage Forms & Strengths

injectable solution

  • 10mg/mL

oral solution

  • 10mg/mL
  • 8mg/mL


  • 20mg
  • 40mg
  • 80mg


Edema associated with congestive heart failure (CHF), liver cirrhosis, and renal disease, including nephrotic syndrome

20-80 mg PO once daily; may be increased by 20-40 mg q6-8hr; not to exceed 600 mg/day

Alternative: 20-40 mg IV/IM once; may be increased by 20 mg q2hr; individual dose not to exceed 200 mg/dose

Refractory CHF may necessitate larger doses

Hypertension, Resistant

20-80 mg PO divided q12hr

Acute Pulmonary Edema/Hypertensive Crisis/Increased Intracranial Pressure

0.5-1 mg/kg (or 40 mg) IV over 1-2 minutes; may be increased to 80 mg if there is no adequate response within 1 hour;not to exceed 160-200 mg/dose  

Hyperkalemia in Advanced Cardiac Life Support (ACLS)

40-80 mg IV

Hypermagnesemia in ACLS

20-40 mg IV q3-4hr PRN

Dosing Modifications

Acute renal failure: 1-3 g/day may be necessary to attain desired response; avoid use in oliguric states

Hepatic impairment: Monitor, especially with high dosages

Dosing Considerations

Use for fluid retention refractory to thiazides or impaired renal function

Overdose management

  • Normal saline may be used for volume replacement
  • Dopamine or norepinephrine may be used to treat hypotension
  • If dysrhythmia due to decreased potassium or magnesium is suspected, replace aggressively
  • Discontinue treatment if no symptoms are apparent after 6 hours

Dosage Forms & Strengths

injectable solution

  • 10mg/mL

oral solution

  • 10mg/mL
  • 8mg/mL


  • 20mg
  • 40mg
  • 80mg


Infants and children: 1-2 mg/kg IV/IM/PO once initially; increased by 1-2 mg/kg q6-8hr (PO) or 1 mg/kg q2hr (IV/IM); individual dose not to exceed 6 mg/kg  

Neonates (<28 days): 0.5-1 mg/kg IV/IM q8-24hr; individual dose not to exceed 2 mg/kg

Resistant Hypertension

<1 year: Safety and efficacy not established

1-17 years: 0.5-2 mg/kg PO q24hr or q12hr; individual dose not to exceed 6 mg/kg/dose  

Excessive diuresis may cause dehydration and electrolyte loss in elderly; lower initial dosages and more gradual adjustments are recommended (eg, 10 mg/day PO)

Increase in blood urea nitrogen (BUN) and loss of sodium may cause confusion in elderly; monitor renal function and electrolytes


20 mg/day PO/IV/IM initially; increased slowly until desired response is obtained



Interaction Checker

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            Adverse Effects


            Hyperuricemia (40%)

            Hypokalemia (14-60%)

            Frequency Not Defined






            Glucose intolerance



            Hearing impairment






            Increased patent ductus arteriosus during neonatal period

            Muscle cramps






            Urinary frequency




            Postmarketing Reports

            Toxic epidermal necrolysis, Stevens-Johnson Syndrome, erythema multiforme, drug rash with eosinophila and systemic symptoms, acute generalized exanthematous pustulosis, exfoliative dermatitis, bullous pemphigoid purpura, pruritus



            Black Box Warnings

            Agent is potent diuretic that, if given in excessive amounts, may lead to profound diuresis with water and electrolyte depletion

            Careful medical supervision is required; dosing must be adjusted to patient's needs


            Documented hypersensitivity to furosemide or sulfonamides



            Use caution in systemic lupus erythematosus, liver disease, renal impairment

            Concomitant ethacrynic acid therapy (increases risk of ototoxicity)

            Risks of fluid or electrolyte imbalance (including causing hyperglycemia, hyperuricemia, gout), hypotension, metabolic alkalosis, severe hyponatremia, severe hypokalemia, hepatic coma and precoma, hypovolemia (with or without hypotension)

            Do not commence therapy in hepatic coma and in electrolyte depletion until improvement is noted

            IV route twice as potent as PO

            Food delays absorption but not diuretic response

            May exacerbate lupus

            Possibility of skin sensitivity to sunlight

            Prolonged use in premature neonates may cause nephrocalcinosis

            Efficacy is diminished and risk of ototoxicity increased in patients with hypoproteinemia (associated with nephrotic syndrome); ototoxicity is associated with rapid injection, severe renal impairment, use of higher than recommended doses, concomitant therapy with aminoglycoside antibiotics, ethacrynic acid, or other ototoxic drugs

            To prevent oliguria, reversible increases in BUN and creatinine, and azotemia, monitor fluid status and renal function; discontinue therapy if azotemia and oliguria occur during treatment of severe progressive renal disease

            FDA-approved product labeling for many medications have included a broad contraindication in patients with a prior allregic reaction to sulfonamides; however, recent studies have suggested that crossreactivity between antibiotic sulfonamides and nonantibiotic sulfonamides is unlikely to occur

            In cirrhosis, electrolyte and acid/base imbalances may lead to hepatic encephalopathy; prior to initiation of therapy, correct electrolyte and acid/base imbalances, when hepatic coma is present

            High doses (> 80 mg) of furosemide may inhibit binding of thyroid hormones to carrier proteins and result in transient increase in free thyroid hormones, followed by overall decrease in total thyroid hormone levels

            In patients at high risk for radiocontrast nephropathy furosemide can lead to higher incidence of deterioration in renal function after receiving radiocontrast compared to high-risk patients who received only intravenous hydration prior to receiving radiocontrast

            Observe patients regularly for possible occurrence of blood dyscrasias, liver or kidney damage, or other idiosyncratic reactions

            Cases of tinnitus and reversible or irreversible hearing impairment and deafness reported

            Hearing loss in neonates has been associated with use of furosemide injection; in premature neonates with respiratory distress syndrome, diuretic treatment with furosemide in the first few weeks of life may increase risk of persistent patent ductus arteriosus (PDA), possibly through a prostaglandin-E-mediated process

            Excessive diuresis may cause dehydration and blood volume reduction with circulatory collapse and possibly vascular thrombosis and embolism, particularly in elderly patients

            Increases in blood glucose and alterations in glucose tolerance tests (with abnormalities of fasting and 2 hour postprandial sugar) have been observed, and rarely, precipitation of diabetes mellitus reported

            Patients with severe symptoms of urinary retention (because of bladder emptying disorders, prostatic hyperplasia, urethral narrowing), the administration of furosemide can cause acute urinary retention related to increased production and retention of urine; these patients require careful monitoring, especially during initial stages of treatment

            Hypokalemia may develop with furosemide, especially with brisk diuresis, inadequate oral electrolyte intake, when cirrhosis is present, or during concomitant use of corticosteroids, ACTH, licorice in large amounts, or prolonged use of laxatives


            Pregnancy & Lactation

            Pregnancy category: C; treatment during pregnancy necessitates monitoring of fetal growth because of risk for higher fetal birth weights

            Lactation: Drug excreted into breast milk; use with caution; may inhibit lactation

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.



            Mechanism of Action

            Loop diuretic; inhibits reabsorption of sodium and chloride ions at proximal and distal renal tubules and loop of Henle; by interfering with chloride-binding cotransport system, causes increases in water, calcium, magnesium, sodium, and chloride


            Bioavailability: 47-64% (PO)

            Onset: 30-60 min (PO/SL); 30 min (IM); 5 min (IV)

            Peak effect: <15 min (IV); 1-2 hr (PO/SL)

            Duration: 2 hr (IV); 6-8 hr (PO)


            Protein bound: 91-99%

            Vd: 0.2 L/kg


            Metabolized in liver (~10%)

            Metabolite: Glucuronide (2-amino-4-chloro-5-sulfamoylanthranilic acid [saluamine]) (activity unknown)


            Half-life: 30-120 min (normal renal function); 9 hr (end-stage renal disease)

            Dialyzable: No

            Renal clearance: 2 mL/min/kg

            Excretion: Urine (PO, 50%; IV, 80%)



            IV Incompatibilities

            Solution: Fructose10W, invert sugar 10% in multiple electrolyte #2

            Additive: Amiodarone (at high concentrations of both drugs), buprenorphine, chlorpromazine, diazepam, dobutamine, eptifibatide, erythromycin lactobionate, gentamicin(?), hydrocortisone(?), isoproterenol, meperidine, metoclopramide, netilmicin, papaveretum, prochlorperazine, promethazine

            Syringe: Caffeine, doxapram, doxorubicin, eptifibatide, metoclopramide, milrinone, droperidol, vinblastine, vincristine

            Y-site: Alatrofloxacin, amiodarone (incompatible at furosemide 10 mg/mL; possibly compatible at 1 mg/mL), chlorpromazine, ciprofloxacin, cisatracurium (incompatible at cisatracurium >2 mg/mL; possibly compatible at 0.1 mg/mL), clarithromycin, diltiazem, diphenhydramine, dobutamine, dopamine, doxorubicin (incompatible at furosemide 10 mg/mL and doxorubicin 2 mg/mL; possibly compatible at furosemide 3 mg/mL and doxorubicin 0.2 mg/mL), droperidol, eptifibatide, esmolol, famotidine(?), fenoldopam, gatifloxacin, gemcitabine, gentamicin(?), hydralazine, idarubicin, labetalol, levofloxacin, meperidine, metoclopramide, midazolam, milrinone, morphine, netilmicin, nicardipine, ondansetron, quinidine, thiopental, vecuronium, vinblastine, vincristine, vinorelbine

            Not specified: Tetracycline

            IV Compatibilities

            Additive: Cimetidine, epinephrine, heparin, nitroglycerin, potassium chloride, verapamil

            Syringe: Heparin

            Y-site: Epinephrine, fentanyl, heparin, norepinephrine, nitroglycerin, potassium chloride, verapamil(?), vitamins B and C

            IV Preparation

            Solution: No preparation needed (available form: 10 mg/mL)

            IV Administration

            Injection: Inject directly or into tubing of actively running IV over 1-2 minutes

            Administer undiluted IV injections at rate of 20-40 mg/min; not to exceed 4 mg/min for short-term intermittent infusion; in children, give 0.5 mg/kg/min, titrated to effect

            Use infusion solution within 24 hours





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            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.