Furosemide
LASIX
Pronunciation: fyoor-OE-se-mide
“Furries see my Laces”
Roller coaster → loop diuretic
Bananas dispersing → ↓ serum potassium
What it isLoop diuretic blocking the NKCC2 cotransporter; volume overload in heart failure, kidney disease and cirrhosis.
Why this oneRapid IV action makes it the workhorse for acute pulmonary edema, but oral absorption is less predictable than torsemide.
What limits itVolume depletion, hypokalemia, hyponatremia and hypomagnesemia require weight, renal-function and electrolyte follow-up.
Pearls
- Only loop diuretic with a home SC form (Furoscix on-body infusor)
Furosemide prescription history
Animated chart of estimated U.S. prescriptions per year, Antihypertensives (1953–2026). Furosemide enters in 1966 (estimated).
FDA-approved for
- edema (1966)
- hypertension (~1966)
Principal riskVolume depletion with hypokalemia and hyponatremia
Sulfonamide
Sulfonamide-derived drug (non-antibacterial) — label warns
No N4 aromatic amine, no N1 heterocycle: cross-reactivity after a sulfonamide-antimicrobial reaction is unlikely — sulfa-allergic patients reacted to sulfonamide non-antibiotics at 9.9% vs 1.6%, less often than to penicillin. The label warns anyway. Ethacrynic acid is the loop diuretic without a sulfonamide.
Open the sulfonamide hypersensitivity presentation → · sources [n] are on its References slide.
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityVolume depletion, electrolyte loss, kidney injury and ototoxicity at high exposure.
FDA label
Read the full label on DailyMed ↗
NO BOXED WARNINGS
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Edema | Adults | 20–80 mg QD | individualized, QD–BID | 600 mg/day (severe edema) |
| Edema | Pediatric | 2 mg/kg QD | 6 mg/kg | |
| Hypertension | Adults | 40 mg BID (80 mg/day) | adjust to response |
Titration May increase by 20–40 mg no sooner than 6–8 h after the previous dose until desired effect (edema)
Renal Undefined
Hepatic Initiate in hospital in cirrhosis with ascites; sudden fluid/electrolyte shifts may precipitate hepatic coma
Edema may be mobilized by dosing 2–4 consecutive days/week
Instructions
- Discontinue if increasing azotemia/oliguria occurs in severe progressive renal disease
Available strengths
- tab 20, 40, 80 mg
- sol 40 mg/5 mL
- sol 10 mg/mL
- inj 10 mg/mL
Contraindications
- Anuria
Cautions
- Ototoxicity (tinnitus, reversible/irreversible hearing loss) — risk with rapid injection, renal impairment, high doses, aminoglycosides/other ototoxics
- Fluid/electrolyte depletion
- Hepatic coma risk in cirrhosis
Adverse reactions
- Hepatic encephalopathy (in hepatocellular insufficiency)
- Pancreatitis
- Jaundice
- Anaphylactoid reactions
- Interstitial nephritis
- Tinnitus/hearing loss
- Blood dyscrasias (aplastic anemia, thrombocytopenia, agranulocytosis)
- Severe skin reactions (TEN, SJS)
- Orthostatic hypotension
- Hyperglycemia, hyperuricemia
Pregnancy Undefined
Lactation Undefined
Cost
Generic entry1985
Open Furosemide in the interactive console ↗
Memory aids: interaction avatars
Open Furosemide in the interactive console ↗
Self-check
- How predictable is oral furosemide absorption versus torsemide?
Less predictable. - Which cotransporter does furosemide block?
NKCC2.