Drug reference

Furosemide

Loop Diuretic · Antihypertensive

Also known as Frusemide, Lasix, Frumil

START

20-40 mg PO/IV once-BID

TYPICAL MAX

600 mg/day (severe HF / CKD) — diminishing returns above 200 mg

STOP IF

Anuria · sulfa allergy (cross-react) · severe hypovolemia/hypokalemia

WATCH

K⁺ · Na⁺ · creatinine · urine output · hearing (high-dose IV)

CDSCO approvedH

Dose laddermg/d

Renal dose adjustmenteGFR mL/min/1.73m²

KDIGO 2024 + manufacturer label

Pharmacokineticsplasma · t hours

ONSET: 30min · PO diuresis (IV 5 min)
PEAK: 1.5h · Cmax
t½: 1.5h · plasma t½
DURATION: 6h · diuretic effect window

EXCRETION

Renal tubular secretion · minimal CYP

route + CYP

INTERACTIONS

12 major

SEVERE in our sources

PREGNANCY

Category C — use only if benefit > risk

FDA category + note

Top interactionssee all 12 →

DigoxinSevereTextbook-citedKDT 7e · p949
LithiumSevereTextbook-citedKDT 7e · p949
MinocyclineSevereTextbook-citedKDT 7e · p949
StreptomycinSevereTextbook-citedKDT 7e · p949

Available in India

13 branded formulations and 44 fixed-dose combinations. Look up specific brands in the Drugs workspace.

Mechanism

Furosemide inhibits the Na+-K+-2Cl- cotransporter (NKCC2) in the thick ascending limb of the loop of Henle, preventing the reabsorption of sodium, potassium, and chloride. This leads to increased excretion of water, sodium, chloride, magnesium, and calcium. The potent diuretic effect reduces fluid overload, lowers blood pressure, and decreases cardiac preload.

Indications

Edema associated with congestive heart failureEdema associated with liver cirrhosisEdema associated with renal disease (including nephrotic syndrome)Hypertension (adjunct in severe or refractory cases)Acute pulmonary edemaHypercalcemia (off-label)Hyperkalemia (off-label)chronic congestive heart failurehypertension (in patients with GFR <30 mL/min or resistant hypertension)edema of nephrotic syndromeedema of liver cirrhosisascites of liver cirrhosisdrug overdose (to induce forced diuresis)hypercalcemia (with isotonic saline)life-threatening hyponatremia (with hypertonic saline)edema associated with chronic kidney diseaseacute pulmonary edema (intravenous)liver cirrhosischronic kidney diseasenephrotic syndromehyponatremiahypercalcemiahypertension with renal insufficiencyvolume management (in supportive care for PAH)Edema associated with heart failureEdema associated with nephrotic syndromeHypertension (especially in patients with azotemia or severe edema associated with vasodilators like minoxidil)Malignant hypertension (acutely)GFR <30-40 mL/minmobilizing edema fluid in CHFrapid symptomatic relief in acute left ventricular failurerestore diuretic response in refractory CHF (when combined with low-rate dopamine infusion)Adjunct in hypertensive emergencies if there is volume overload (acute LVF, pulmonary edema, CHF) or cerebral edema (in encephalopathy)Edema (cardiac, hepatic, renal, nephrotic, resistant, chronic renal failure)Impending acute renal failure (to decrease need for dialysis)Acute pulmonary edema (acute LVF, following MI)Cerebral edema (combined with osmotic diuretics)Hypertension (in presence of renal insufficiency, CHF, resistant cases, hypertensive emergencies)Along with blood transfusion in severe anaemia (to prevent volume overload)With hypertonic saline in hyponatraemiaHypercalcaemia of malignancyHypertensionCKD with GFR <30Symptomatic HFPulmonary edema

Dosing

Adult: Oral: Initial 20-80 mg once daily or in 2 divided doses; titrate up to 600 mg/day for severe cases. IV/IM: 20-40 mg administered over 1-2 minutes; may be increased by 20 mg increments every 2 hours until desired effect. For acute pulmonary edema, IV: 40 mg initially, followed by 80 mg if needed after 1 hour.
Pediatric: Oral: Initial 2 mg/kg once daily, may be increased by 1-2 mg/kg every 6-8 hours up to a maximum of 6 mg/kg/dose. IV/IM: Initial 1 mg/kg; may be increased by 1 mg/kg every 2 hours up to a maximum of 6 mg/kg/dose. Max 40 mg/day for infants <1 year, 80 mg/day for children >1 year.
Renal adjustment: **CrCl > 30 mL/min:** No dose adjustment for usual doses. **CrCl < 30 mL/min:** Higher doses may be required; initiate 40 mg orally/IV, with a maximum daily dose up to 120-160 mg. Avoid in anuric patients unresponsive to furosemide. **For dialysis patients:** Administer after dialysis sessions if needed for fluid control; supplemental doses are generally not required.
Max dose: 80 mg/day oral (usual); up to 200 mg q6h IV in renal failure

Pharmacokinetics

Onset

Oral: 30-60 minutes; IV: 5 minutes

Peak effect

Oral: 1-2 hours; IV: 20-60 minutes

Duration

3–6 hours

Half-life

~1.5

Bioavailability

~60% (variable)

Protein binding

>95% (primarily albumin)

Metabolism

~35% metabolism (predominantly in the kidney)

Excretion

~65% renal excretion of intact drug

Contraindications

Anuria
Hypersensitivity to furosemide or sulfonamides
Hepatic coma and states of electrolyte depletion until condition is improved
Severe hypokalemia
Severe hyponatremia
Hypovolemia/dehydration
Severe renal failure with anuria unresponsive to furosemide
severe Na+ depletion
severe volume depletion
hypersensitivity to sulfonamides
anuria unresponsive to a trial dose of loop diuretic
sulfonamide hypersensitivity
patient may be hypovolemic due to pressure induced natriuresis (especially in eclampsia, pheochromocytoma)
Toxaemia of pregnancy

Side effects

Common

DehydrationElectrolyte disturbances (hypokalemia, hyponatremia, hypomagnesemia, hypochloremia, hypocalcemia)Orthostatic hypotensionIncreased urinationDizzinessHeadacheBlurred visionMuscle crampsTinnitusasymptomatic hyperuricemiahearing impairmentvertigosense of fullness in the earshyperglycemia (infrequently precipitating diabetes mellitus)increased plasma LDL cholesterolincreased plasma triglyceridesdecreased plasma HDL cholesterolskin rashesphotosensitivityparesthesiasGI disturbanceshypokalemiahyponatremiahypomagnesemiahyperuricemiahypocalcemiaglucose intolerancehypotensionreduction in GFRelectrolyte disturbancehypokalaemiaalkalosiscarbohydrate intoleranceIncreased K+ excretion (less than thiazides)Increased Ca2+ excretionIncreased Mg2+ excretionHyperuricaemia (lower than thiazides)Small rise in blood sugar level (less than thiazides)Mild alkalosis (at high doses)WeaknessFatigueNauseaVomitingDiarrhoeaGiddinessImpotenceVolume depletion

Serious

Ototoxicity (especially with rapid IV injection, high doses, or in renal impairment)
Severe hypotension
Hypovolemic shock
Cardiac arrhythmias (due to electrolyte imbalance)
Stevens-Johnson syndrome
Toxic epidermal necrolysis
Pancreatitis
Aplastic anemia
Agranulocytosis
depletion of total-body Na+
hyponatremia
extracellular fluid volume depletion
hypotension
reduced GFR
circulatory collapse
thromboembolic episodes
hepatic encephalopathy (in liver disease)
hypochloremic alkalosis
hypokalemia
cardiac arrhythmias (particularly with cardiac glycosides)
hypomagnesemia
hypocalcemia (rarely leading to tetany)
ototoxicity (usually reversible, most frequently with rapid intravenous administration)
gout (rarely)
bone marrow depression
nephrotoxicity
ototoxicity
Ototoxicity occurs at concentrations >25 µg/mL.
mental disorientation (due to hypokalemic alkalosis and increased ammonia in hepatic encephalopathy)
urinary retention (in prostatic hypertrophy)
Cardiac arrhythmias (due to hypokalaemia)
Hearing loss (rarely, in presence of renal insufficiency)
Rashes
Photosensitivity
Blood dyscrasias

Pregnancy & lactation

Pregnancy

Category C — use only if benefit > risk

Drug interactions

Digoxin

Severe

Textbook-cited

Digoxin toxicity (arrhythmias, nausea, visual disturbances).

Co-prescribe potassium-sparing diuretic or potassium supplements

Source: KDT 7e · p949

Lithium

Severe

Textbook-cited

Lithium toxicity.

Reduce lithium dose and monitor serum levels

Source: KDT 7e · p949

Minocycline

Severe

Textbook-cited

Severe vestibular toxicity (vertigo, dizziness).

Avoid concurrent use

Source: KDT 7e · p949

Streptomycin

Severe

Textbook-cited

Ototoxicity (hearing loss) and nephrotoxicity

Avoid concurrent use; if unavoidable, monitor renal function and audiometry

Source: KDT 7e · p949

Tobramycin

Severe

Textbook-cited

Ototoxicity (hearing loss) and nephrotoxicity.

Avoid concurrent use; if unavoidable, monitor renal function and audiometry

Source: KDT 7e · p949

Aminoglycosides

Severe

Textbook

Increased risk of ototoxicity (e.g., tinnitus, hearing impairment, deafness, vertigo).

Not explicitly stated, but implies careful monitoring or avoidance if possible.

Source: G&G 14e · p566

Digitalis Glycosides

Severe

Textbook

Increased digitalis-induced arrhythmias.

Not explicitly stated, but implies careful monitoring of potassium levels.

Source: G&G 14e · p566

Paclitaxel

Severe

Textbook

Increased risk of ototoxicity (e.g., tinnitus, hearing impairment, deafness, vertigo).

Not explicitly stated, but implies careful monitoring or avoidance if possible.

Source: G&G 14e · p566

Amikacin

Severe

Database

Additive ototoxicity. Loop diuretics increase aminoglycoside concentrations in the inner ear and kidney, enhancing both ototoxic and nephrotoxic effects.

Avoid concurrent use if possible. If unavoidable, monitor renal function daily, serum aminoglycoside levels, and hearing. Keep course as short as possible.

Source: Kimi deep-research + Cla · p949

Aminolevulinic Acid

Severe

Database

Drug interaction classified as: synergy

Source: DDInter

Amiodarone

Severe

Database

Drug interaction classified as: synergy.

Source: DDInter

Arsenic Trioxide