What is furosemide, and what is it used for?
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?
Yes
What are the side effects of furosemide?
Common side effects of furosemide are:
- low blood pressure,
- dehydration and
- electrolyte depletion (for example, sodium, potassium).
Other important side effects include:
- jaundice,
- ringing in the ears (tinnitus),
- sensitivity to light (photophobia),
- rash,
- pancreatitis,
- nausea,
- diarrhea,
- abdominal pain, and
- dizziness.
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:

SLIDESHOW
How to Lower Blood Pressure: Exercise Tips See SlideshowWhat 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.
The recommended dose for treating hypertension is 40 mg twice daily. The dose of other blood pressure medications should be reduced by half when furosemide is added.
Latest High Blood Pressure News
Daily Health News
Which drugs or supplements interact with furosemide?
Administration of furosemide with aminoglycoside antibiotics (for example, gentamicin) or ethacrynic acid (Edecrin, another diuretic) may cause hearing damage.
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.
Furosemide also may reduce excretion of lithium (Eskalith, Lithobid) by the kidneys, causing increased blood levels of lithium and possible side effects from lithium.
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.
When combined with other antihypertensive drugs there is an increased risk of low blood pressure or reduced kidney function.
Nonsteroidal anti-inflammatory drugs (for example., ibuprofen, indomethacin [Indocin, Indocin-SR]) may interfere with the blood pressure reducing effect of furosemide.
This medication also interacts with certain drugs like:
- cisplatin (Platinol-AQ),
- cyclosporine,
- methotrexate (Rheumtrex, Trexall),
- phenytoin,
- antibiotics,
- heart medications,
- laxatives,
- steroids.
Tell your doctor or other health care professional about any vitamins or supplements you are taking.
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.
Furosemide is secreted in breast milk. Nursing mothers should avoid breastfeeding while taking furosemide.
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.

QUESTION
Salt and sodium are the same. See AnswerSummary
Furosemide (Lasix) is a diuretic medicine that doctors prescribe to treat excess accumulation of fluid or swelling of the body (edema) caused by cirrhosis, chronic kidney failure, heart failure, and kidney disease. Review the side effects, drug interactions, dosage, and pregnancy and breastfeeding information before using furosemide.
Multimedia: Slideshows, Images & Quizzes
-
High Blood Pressure (Hypertension) Quiz: Symptoms, Signs & Causes
Take this quiz and test your IQ of high blood pressure (hypertension), the cardiovascular disease that causes most strokes and...
-
Kidney Disease Quiz: Test Your Medical IQ
Kidney disease is common. Take this kidney disease quiz to test your knowledge and learn the symptoms, causes and types of kidney...
Related Disease Conditions
-
Cirrhosis (Liver)
Cirrhosis of the liver refers to a disease in which normal liver cells are replaced by scar tissue caused by alcohol and viral hepatitis B and C. This disease leads to abnormalities in the liver's ability to handle toxins and blood flow, causing internal bleeding, kidney failure, mental confusion, coma, body fluid accumulation, and frequent infections. Symptoms include yellowing of the skin (jaundice), itching, and fatigue. The prognosis is good for some people with cirrhosis of the liver, and the survival can be up to 12 years; however the life expectancy is about 6 months to 2 years for people with severe cirrhosis with major complications.
-
Kidney (Renal) Failure
Kidney failure can occur from an acute event or a chronic condition or disease. Prerenal kidney failure is caused by blood loss, dehydration, or medication. Some of the renal causes of kidney failure include sepsis, medications, rhabdomyolysis, multiple myeloma, and acute glomerulonephritis. Post renal causes of kidney failure include bladder obstruction, prostate problems, tumors, or kidney stones.Treatment options included diet, medications, or dialysis.
-
Congestive Heart Failure (CHF)
Congestive heart failure (CHF) refers to a condition in which the heart loses the ability to function properly. Heart disease, high blood pressure, diabetes, myocarditis, and cardiomyopathies are just a few potential causes of congestive heart failure. Signs and symptoms of congestive heart failure may include fatigue, breathlessness, palpitations, angina, and edema. Physical examination, patient history, blood tests, and imaging tests are used to diagnose congestive heart failure. Treatment of heart failure consists of lifestyle modification and taking medications to decrease fluid in the body and ease the strain on the heart. The prognosis of a patient with congestive heart failure depends on the stage of the heart failure and the overall condition of the individual.
-
Ascites
Ascites, the accumulation of fluid in the abdominal cavity is most commonly caused by cirrhosis of the liver. Some of the other causes of ascites include portal hypertension, congestive heart failure, blood clots, and pancreatitis. The most common symptoms include increased abdominal girth and size, abdominal bloating, and abdominal pain. Treatment depends on the cause of ascites.
-
Edema (Pitting)
Edema is the swelling of tissues as a result of excess water accumulation. Peripheral edema occurs in the feet and legs. There are two types of edema, non-pitting edema and pitting edema. Causes of pitting edema is caused by systemic diseases (most commonly involving the heart, liver, and kidneys), and medications. Local conditions that cause edema are thrombophlebitis and varicose veins. Edema or swelling of the legs, feet, ankles, and face are common during pregnancy. Idiopathic edema is edema in which the cause is not known. Pitting edema is scored on pitting edema measurement scales. Edema is generally treated with medication.
-
Pulmonary Edema
Pulmonary edema (swelling or fluid in the lungs) can either be caused by cardiogenic causes (congestive heart failure, heart attacks, abnormal heart valves) or noncardiogenic causes such as ARDS, kidney failure, high altitude, pneumothorax, pleural effusion, aspirin overdose, pulmonary embolism, and infections. The treatment of pulmonary edema depends on the cause of the condition.
-
Low Potassium (Hypokalemia)
Potassium is an essential electrolyte necessary for cell function. Low potassium (hypokalemia) may be caused by diarrhea, vomiting, ileostomy, colon polyps, laxative use, diuretics, elevated corticosteroid levels, renal artery stenosis, and renal tubular acidosis, or other medications. Symptoms of low potassium include weakness, aches, and cramps of the muscles. Treatment is dependent upon the cause of the low potassium (hypokalemia).
-
High Blood Pressure Treatment (Natural Home Remedies, Diet, Medications)
High blood pressure (hypertension) means high pressure (tension) in the arteries. Treatment for high blood pressure include lifestyle modifications (alcohol, smoking, coffee, salt, diet, exercise), drugs and medications such as ACE inhibitors, angiotensin receptor blockers, beta blockers, diuretics, calcium channel blockers (CCBs), alpha blockers, clonidine, minoxidil, and Exforge.
-
Heart Failure
Heart failure (congestive) is caused by many conditions including coronary artery disease, heart attack, cardiomyopathy, and conditions that overwork the heart. Symptoms of heart failure include congested lungs, fluid and water retention, dizziness, fatigue and weakness, and rapid or irregular heartbeats. There are two types of congestive heart failure, systolic or left-sided heart failure; and diastolic or right-sided heart failure. Treatment, prognosis, and life-expectancy for a person with congestive heart failure depends upon the stage of the disease.
-
Hypertensive Kidney Disease
High blood pressure can damage the kidneys and is one of the leading causes of kidney failure (end-stage renal kidney disease). Kidney damage, like hypertension, can be unnoticeable and detected only through medical tests. If you have kidney disease, you should control your blood pressure. Other treatment options include prescription medications.
-
Superior Vena Cava Syndrome
Superior vena cava syndrome is compression of the superior vena cava vein located in the upper chest. Causes of superior vena cava include lung cancer, lymphoma, other cancers in the chest, blood clots in the superior vena cava, or infection. Symptoms of the syndrome include shortness of breath. Superior vena cava syndrome is diagnosed by ultrasound, chest X-ray, CT scan, and in some cases biopsy. Treatment depends upon the cause of the syndrome.
-
Primary Biliary Cirrhosis (PBC) Treatment
Primary biliary cirrhosis (PBC) is thought to be an autoimmune disorder that involves the deterioration of the liver's small bile ducts. These ducts are crucial to transport bile to the small intestine, digesting fats and removing wastes. Symptoms of PBC are edema, itching, elevated cholesterol, malabsorption of fat, liver cancer, gallstones, urinary tract infections (UTIs), and hypothyroidism. Treatments include ursodeoxycholic acid (UDCA); colchicine (Colcrys); and immunosuppressive medications, such as corticosteroids; obeticholic acid (Ocaliva); and medications that treat PBC symptoms. For PBC that is associated with cirrhosis of the liver, liver transplantation may be indicated in extreme cases.
-
Bladder Spasms
People who have bladder spasms, the sensation occurs suddenly and often severely. A spasm itself is the sudden, involuntary squeezing of a muscle. A bladder spasm, or "detrusor contraction," occurs when the bladder muscle squeezes suddenly without warning, causing an urgent need to release urine. The spasm can force urine from the bladder, causing leakage. When this happens, the condition is called urge incontinence or overactive bladder.
-
Febrile Seizures
Febrile seizures, or convulsions caused by fever, can be frightening in small children or infants. However, in general, febrile seizures are harmless. Febrile seizure is not epilepsy. It is estimated that one in every 25 children will have at least one febrile seizure. It is important to know what to do to help your child if he/she has a febrile seizure. Some of the features of a febrile seizure include: losing consciousness, shaking, moving limbs on both sides of the body, lasts 1-2 minutes. Less commonly, a febrile seizure may only affect one side of the body.
Treatment & Diagnosis
- High Blood Pressure FAQs
- Kidney Disease FAQs
- How To Reduce Your Medication Costs
- Pharmacy Visit, How To Get The Most Out of Your Visit
- Indications for Drugs: Approved vs. Non-approved
- Drugs: Buying Prescription Drugs Online Safely
- Drugs: The Most Common Medication Errors
- Medication Disposal
- Dangers of Mixing Medications
- Generic Drugs, Are They as Good as Brand-Names?
Medications & Supplements
- High Blood Pressure Drugs (Hypertension)
- Lasix Side Effects, Warnings, and Drug Interactions
- hydrochlorothiazide (Microzide, Hydrodiuril)
- Drugs: Questions to Ask Your Doctor or Pharmacist about Your Drugs
- Drug Interactions
- Congestive Heart Failure Medications
- triamterene and hydrochlorothiazide
- Aldactone (spironolactone) vs. Lasix (furosemide)
- torsemide (Demadex)
Prevention & Wellness
Subscribe to MedicineNet's Heart Health Newsletter
By clicking "Submit," I agree to the MedicineNet Terms and Conditions and Privacy Policy. I also agree to receive emails from MedicineNet and I understand that I may opt out of MedicineNet subscriptions at any time.
Health Solutions From Our Sponsors

Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.