Skip to main content


Generic name: furosemide (oral/injection) [ fur-OH-se-mide ]
Brand names: Lasix, Diaqua-2, Lo-Aqua, Furoscix
Dosage forms: oral tablet (20 mg; 40 mg; 80 mg), oral liquid (10 mg/mL), oral solution (40 mg/5 mL), ... show all 6 dosage forms
Drug class: Loop diuretics

Medically reviewed by Melisa Puckey, BPharm. Last updated on Jan 9, 2024.

What is furosemide?

Furosemide is a loop diuretic used to treat fluid retention (edema) in people with congestive heart failure, liver disease, or a kidney disorder such as nephrotic syndrome. Furosemide is also used to treat high blood pressure (hypertension).

Furosemide works by increasing the amount of urine the body makes, which helps reduce swelling and symptoms of fluid retention and helps lower high blood pressure. Furosemide tablets are sometimes called water pills as they increase how much you urinate.

Furosemide is also known as frusemide in some countries. Furosemide became an FDA-approved medicine on July 1, 1966, and is available as tablets (Lasix), oral liquid, injection, and intravenous solution.

Furosemide side effects

Common furosemide side effects may include:

Serious furosemide side effects 

Get emergency medical help if you have signs of an allergic reaction to furosemide (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Furosemide may cause other serious side effects. Call your doctor at once if you have:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


You should not use furosemide if you are unable to urinate.

Using more than your recommended dose will not make this medicine more effective. High doses of tis medicine may cause irreversible hearing loss.

Before using this medicine, tell your doctor if you have kidney disease, enlarged prostate, urination problems, cirrhosis or other liver disease, an electrolyte imbalance, high cholesterol, gout, lupus, diabetes, or an allergy to sulfa drugs.

Tell your doctor if you have recently had an MRI (magnetic resonance imaging) or any type of scan using a radioactive dye that is injected into your veins. Do not take more of this medication than is recommended.

If you are being treated for high blood pressure, keep using this medicine even if you feel fine. High blood pressure often has no symptoms.

Furosemide is a potent diuretic which, if given in excessive amounts, can lead to a profound diuresis with water and electrolyte depletion. Therefore, careful medical supervision is required and dose schedule must be adjusted to the individual patient’s needs

Tell your doctor about all your other medicines. Some drugs should not be used with furosemide.

Before taking this medicine

You should not use furosemide if you are allergic to it, if you are unable to urinate or have hepatic cirrhosis.

To make sure furosemide is safe for you, tell your doctor if you have ever had:

Tell your doctor if you have an MRI (magnetic resonance imaging) or any type of scan using a radioactive dye that is injected into a vein. Contrast dyes and furosemide can harm your kidneys.

Furosemide on-body infusor (Furoscix) can only be used for congestion due to fluid overload in adults with NYHA Class II/III chronic heart failure, and is not not indicated for emergency situations or in patients with acute pulmonary edema. 


It is not known if furosemide will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.


It may not be safe to breastfeed while using furosemide. Ask your doctor about any risk. Furosemide may slow breast milk production.

How should I use furosemide?

Take furosemide exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets.

Furosemide oral tablets and liquid are taken by mouth. Measure liquid medicine with the supplied measuring device (not a kitchen spoon).

Furosemide injection is given in a muscle, under the skin, or in a vein. A healthcare provider will give you this injection if you are unable to take the medicine by mouth.

Furosemide infusion (Furoscix) lasts about 5 hours. Furoscix should not get wet. Do not bathe, shower, swim or exercise while wearing the infusor. Also, do not apply any products such as lotions or creams in the area where the infusor is placed. Furoscix is not for chronic use and should be replaced with oral diuretics as soon as practical.

It is not recommended to travel by car or airplane while using Furoscix. Also do not use the infusor within 12 inches of mobile phones, tablets, computers, or wireless accessories such as remote control, or bluetooth devices.

General furosemide dosing information.

Do not use more than your recommended dose. High doses of furosemide may cause irreversible hearing loss.

Doses are based on weight in children and teenagers. Your child's dose may change if the child gains or loses weight.

This medicine will make you urinate more often and you may get dehydrated easily. Follow your doctor's instructions about using potassium supplements or getting enough salt and potassium in your diet.

Your blood pressure will need to be checked often and you may need other medical tests.

If you have high blood pressure, keep using furosemide even if you feel well. High blood pressure often has no symptoms.

If you need surgery, tell the surgeon ahead of time that you are using furosemide.

Dosing Information

Usual Adult Dose for Edema associated with Congestive Heart Failure, Cirrhosis of the Liver, and Renal Disease (including Nephrotic Syndrome):

Oral: Initial dose: 20 to 80 mg orally once; may repeat with the same dose or increase by 20 or 40 mg no sooner than 6 to 8 hours after the previous dose until the desired diuretic effect has been obtained.
Maintenance dose: Administer the dose that provided the desired diuretic effect once or twice a day (e.g., at 8 am and 2 pm).
Comments:Edema may be most efficiently and safely mobilized by giving this drug on 2 to 4 consecutive days each week. When doses greater than 80 mg/day are given for prolonged periods of time, careful clinical observation and laboratory monitoring are particularly advisable.

Usual Adult Dose for Pulmonary Edema:

IV: 40 mg IV slowly over 1 to 2 minutes; if a satisfactory response doesn't occur within one hour, may increase to 80 mg IV slowly over 1 to 2 minutes.
Use: Adjunctive therapy in acute pulmonary edema. IV administration of this drug is indicated when a rapid onset of diuresis is desired (e.g., in acute pulmonary edema).

Usual Adult Dose for Hypertension:

Oral: Initial dose: 80 mg/day, usually divided into 40 mg orally twice a day
Use: Treatment of hypertension alone or in combination with other antihypertensive agents.

Usual Pediatric Oral Dose for Edema:

Initial dose: 2 mg/kg orally once; if the diuretic response to the initial dose is not satisfactory, may increase by 1 or 2 mg/kg and administer no sooner than 6 to 8 hours after the previous dose.
Maintenance dose: Adjust to minimum effective dose.
Use: Treatment of edema associated with congestive heart failure, cirrhosis of the liver and renal disease, including the nephrotic syndrome, especially when an agent with greater diuretic potential is desired.

What happens if I miss a dose?

Furosemide is sometimes used only once, so you may not be on a dosing schedule. If you are using the medication regularly, use the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include feeling very thirsty or hot, heavy sweating, hot and dry skin, extreme weakness, or fainting.

What should I avoid while using furosemide?

Avoid getting up too fast from a sitting or lying position, or you may feel dizzy.

Avoid becoming dehydrated. Follow your doctor's instructions about the type and amount of liquids you should drink while you are using furosemide.

Drinking alcohol with this medicine can cause side effects.

Furosemide could make you sunburn more easily. Avoid sunlight or tanning beds. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

If you have high blood pressure, ask a doctor or pharmacist before taking any medicines that can raise your blood pressure, such as diet pills or cough-and-cold medicine.

What other drugs will affect furosemide?

Sometimes it is not safe to use certain medicines at the same time. Some drugs can affect your blood levels of other drugs you use, which may increase side effects or make the medicines less effective

If you also take sucralfate, take your furosemide dose 2 hours before or 2 hours after you take sucralfate.

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may interact with furosemide, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Frequently asked questions

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use furosemide only for the for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.