Medscape is available in 5 Language Editions – Choose your Edition here.


furosemide (Rx)Brand and Other Names:Lasix


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

furosemide and

No Results

     activity indicator 
    No Interactions Found
    Interactions Found


      Serious - Use Alternative

        Significant - Monitor Closely


            Sort by :  
             activity indicator 

            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






            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 diabetes mellitus, 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

            Risk of ototoxicity (tinnitus, reversible or irreversible hearing impairment)

            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)

            To prevent oliguria, reversible increases in BUN and creatinine, and azotemia, monitor fluid status and renal function

            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


            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





            FormularyPatient Discounts

            To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

            Adding plans allows you to:

            • View the formulary and any restrictions for each plan.
            • Manage and view all your plans together – even plans in different states.
            • Compare formulary status to other drugs in the same class.
            • Access your plan list on any device – mobile or desktop.

            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            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.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
            Add or Remove Plans
            Plans for
            Select State:
            Non-Medicare PlansMedicare Plans

            Select a box to add or remove a plan.

            Select a class to view formulary status for similar drugs

            Additional Offers
            Email to Patient



            The recipient will receive more details and instructions to access this offer.

            By clicking send, you acknowledge that you have permission to email the recipient with this information.

            Email Forms to Patient



            The recipient will receive more details and instructions to access this offer.

            By clicking send, you acknowledge that you have permission to email the recipient with this information.

            All material on this website is protected by copyright, Copyright © 1994-2016 by WebMD LLC. This website also contains material copyrighted by 3rd parties.