What is furosemide, and how does it work (mechanism of action)?
Furosemide (Lasix) is a potent diuretic (water pill) that is used to eliminate water and salt from the body. In the kidneys, salt (composed of sodium and chloride), water, and other small molecules normally are filtered out of the blood and into the tubules of the kidney. The filtered fluid ultimately becomes urine. Most of the sodium, chloride and water that is filtered out of the blood is reabsorbed into the blood before the filtered fluid becomes urine and is eliminated from the body.
Furosemide works by blocking the absorption of sodium, chloride, and water from the filtered fluid in the kidney tubules, causing a profound increase in the output of urine (diuresis). The onset of action after oral administration is within one hour, and the diuresis lasts about 6-8 hours. The onset of action after injection is five minutes and the duration of diuresis is two hours. The diuretic effect of furosemide can cause depletion of sodium, chloride, body water and other minerals. Therefore, careful medical supervision is necessary during treatment. The FDA approved furosemide in July 1982.
Doctors prescribe furosemide to treat excess accumulation of fluid or swelling of the body (edema) caused by cirrhosis, chronic kidney failure, heart failure, and kidney disease. Doctors also prescribe furosemide in conjunction with other high blood pressure pills to treat high blood pressure (hypertension).
Is furosemide available as a generic drug?
GENERIC AVAILABLE: Yes
Do I need a prescription for this drug?
What are the side effects of furosemide?
Common side effects of furosemide are:
Other important side effects include:
Increased blood sugar and uric acid levels also may occur.
Profound diuresis with water and electrolyte depletion can occur if Lasix is given in excess amounts. Other side effects and adverse effects of this medicine include:
- Gut (gastrointestinal or GI) reactions like pancreatitis, jaundice, anorexia, cramping, diarrhea, constipation, nausea, and vomiting
- Systemic hypersensitivity reactions like severe anaphylactic shock, necrotizing angiitis, and interstitial nephritis
- Central nervous system (CNS) reactions like vertigo, headaches, blurred vision, tinnitus, and hearing loss
- Blood reactions like anemia, leukopenia, thrombocytopenia, and eosinophilia
- Hypersensitive skin reactions like rash, itching, hives, photosensitivity, exfoliative dermatitis, and Steven-Johnson syndrome
- Heart reactions like orthostatic hypotension (fainting or dizziness when standing up) and an increase in triglyceride and cholesterol levels
Other reactions include:
What is the dosage for furosemide?
The usual starting oral dose for treatment of edema in adults is 20-80 mg as a single dose. The same dose or an increased dose may be administered 6-8 hours later. Doses may be increased 20-40 mg every 6-8 hours until the desired effect occurs. The effective dose may be administered once or twice daily. Some patients may require 600 mg daily.
The starting oral dose for children is 2 mg/kg. The starting dose may be increased by 1-2 mg/kg every 6 hours until the desired effect is achieved. Doses greater than 6 mg/kg are not recommended.
Which drugs or supplements interact with furosemide?
Furosemide competes with aspirin for elimination in the urine by the kidneys. Concomitant use of furosemide and aspirin may, therefore, lead to high blood levels of aspirin and aspirin toxicity.
Sucralfate (Carafate) reduces the action of furosemide by binding furosemide in the intestine and preventing its absorption into the body. Ingestion of furosemide and sucralfate should be separated by two hours.
This medication also interacts with certain drugs like:
Is furosemide safe to take if I’m pregnant or breastfeeding?
Furosemide should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus.
What else should I know about furosemide?
What preparations of furosemide are available?
Tablets: 20, 40 and 80 mg. Oral solution: 10 mg/ml and 8 mg/ml. Injection: 10 mg/ml
How should I keep furosemide stored?
Furosemide should be stored at room temperature in a light resistant container.
Medically Reviewed on 6/27/2019
Reference: FDA Prescribing Information