Uses

What is furosemide used for?

Furosemide is a diuretic, also called a water pill, that is commonly used to reduce edema (fluid retention) caused by the following conditions.

  • Congestive heart failure, which is a condition where the heart is not pumping as well as it should
  • Liver disease, such as cirrhosis, which can lead to a buildup of fluid in the abdomen (ascites)
  • Kidney disease, including protein in the urine (nephrotic syndrome)

Furosemide may also be used to treat high blood pressure (hypertension).

Furosemide may also be used for other conditions as determined by your healthcare provider.

How does furosemide work (mechanism of action)?

Furosemide works by increasing how much you pee. It does this by helping the kidneys remove electrolytes, such as sodium (salt), and water from the body.

How is furosemide supplied (dosage forms)?

Furosemide is available in the following dosage forms that are taken by mouth.

  • 8 mg/mL oral solution
  • 10 mg/mL oral solution
  • 20 mg oral tablets
  • 40 mg oral tablets
  • 80 mg oral tablets

Furosemide is also available in injectable forms.

How should I store furosemide?

Furosemide should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C), for shorter periods of time, such as when transporting it. Store in a cool, dry place. Keep tightly closed. Protect from light.   

Side Effects

What are the most common side effects of furosemide?

The most common side effects of furosemide are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Low blood pressure (see below)
  • Electrolyte changes and increased blood sugar (see below)
  • An increase in how much you pee

There may be other side effects of furosemide that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of furosemide?

While less common, the most serious side effects of furosemide are described below, along with what to do if they happen.

Low Blood Pressure with Worsening Kidney Function. Water loss from furosemide can lower your blood pressure too much and cause dehydration. Both may lead to problems that are more serious than light-headedness. Poor blood flow to important organs such as your kidneys can occur, especially if you are elderly. Drink enough water to stay hydrated, especially if you have excess sweating, vomiting, or diarrhea. Get out of bed or from a seated position slowly. Tell your healthcare provider right away if you have any of the following symptoms.

  • Dizziness, feeling lightheaded, or fainting
  • Confusion
  • Feeling weak or tired
  • Reduced amount of urine (pee)
  • Sudden weight gain
  • Dizziness, feeling lightheaded, or fainting
  • Confusion
  • Feeling weak or tiredReduced need to pee
  • Sudden weight gain
  • Increased thirst
  • Dark or strong-smelling pee
  • Dry mouth
  • Sunken eyes
  • Headache
  • Fast heartbeat

Electrolyte Changes and Increased Blood Sugar. Furosemide may increase your blood sugar (glucose) levels and cause changes to the levels of certain minerals in your body, called electrolytes. For example, it may cause low potassium levels (hypokalemia), low sodium levels (hyponatremia), low magnesium levels (hypomagnesemia), low calcium levels (hypocalcemia), low chloride levels (hypochloremia), or high glucose levels (hyperglycemia). These changes can be serious. Your healthcare provider will do bloodwork to check your glucose and electrolyte levels, especially if you take certain other medicines. Keep your appointments to have your blood checked. Call your healthcare provider if you have any of the following symptoms.

  • Weakness
  • Unusual tiredness
  • Muscle cramps or twitching
  • Constipation
  • Nausea, vomiting, or loss of appetite
  • Dizziness
  • Restlessness or irritability
  • Difficulty breathing
  • Confusion or decreased alertness
  • Abnormal heart rhythm
  • Seizures

Hearing Loss. Furosemide may be associated with hearing loss, which is also called ototoxicity. Tell your healthcare provider right away if you have hearing loss or if you hear a ringing or roaring sound in your ears while taking furosemide.

Severe Allergic Reactions. Furosemide may cause allergic reactions, which can be serious. Stop using furosemide and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use furosemide?

Allergies to Ingredients. People who are allergic to any of the following should not use furosemide.

  • Furosemide
  • Lasix
  • Furoscix
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific furosemide products they stock.

No Urine Production. Do not take furosemide if you are making very little to no pee. This condition is also called anuria.

Very Low Electrolytes. If you have low electrolytes, including low sodium or potassium, furosemide may not be safe to use. Your healthcare provider may measure your electrolytes before starting furosemide. Low electrolytes are not usually something you can feel, so it is important to make it to your scheduled blood work appointments.  

What should I know about furosemide before using it?

Do not take furosemide unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share furosemide with other people, even if they have the same condition as you. It may harm them.

Keep furosemide out of the reach of children.

Furosemide can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how furosemide affects you. 

People who are age 65 or older can be at greater risk for some side effects from furosemide. Talk to your healthcare provider about your risks if you are in this age group.

Your skin may be very sensitive to light from the sun and devices that give off similar light, such as sunlamps and tanning beds, while you are taking certain drugs, including furosemide. This is called photosensitivity. Use sunscreen and wear a hat and clothes that cover your skin if you need to be in the sunlight.

What should I tell my healthcare provider before using furosemide?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if furosemide is right for you.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Heart failure
  • Liver problems
  • Kidney problems
  • Persistent or severe diarrhea or vomiting, which can lead to dehydration
  • Low electrolytes, including potassium and sodium
  • Abnormal heart rhythm (arrhythmias)
  • Diabetes 
  • Gout
  • Prostate problems
  • Urinary retention
  • Systemic lupus erythematosus

Sulfa Allergy. Some people who have a sulfa allergy may also be allergic to furosemide. A sulfa allergy is a rash or more serious reaction to sulfa, or sulfonamide, medicines. Sulfa medicines include sulfamethoxazole, sulfadiazine silver, or sulfasalazine. Tell your healthcare provider if you have any allergies to medicines. Your healthcare provider can help you decide if it is safe for you to take furosemide.

Other Medicines and Supplements. Furosemide may interact with other medicines and supplements. Before using furosemide, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how furosemide could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take furosemide while you are pregnant or trying to get pregnant.

Breastfeeding. Furosemide passes into breast milk. Furosemide may reduce milk production. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take furosemide while breastfeeding.

Interactions

Does furosemide interact with foods or drinks?

There are no known interactions between furosemide and foods or drinks. However, since furosemide affects electrolytes, it is important to discuss your intake of electrolytes, including sodium and potassium, with your healthcare provider.

It is unknown if drinking alcohol will affect furosemide. The risk of dizziness may be increased if you drink alcohol while taking furosemide.

Does furosemide interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using furosemide.

  • Any aminoglycoside antibiotic, such as neomycin or gentamicin, which is a medicine usually given by injection to treat infections
  • Ethacrynic acid, which is used to treat excess fluid
  • Cisplatin, which is used to treat certain cancers
  • Lithium, which is a medicine commonly used for certain mental health conditions
  • Any angiotensin-converting enzyme inhibitor (ACEi), which is a medicine used for many different reasons, such as lowering high blood pressure
  • Any angiotensin II receptor blocker (ARB), which is a medicine used for many different reasons, such as lowering high blood pressure
  • Sucralfate, which is a medicine that is commonly used for stomach or intestine ulcers
  • Phenytoin, which is used to treat conditions such as seizures
  • Methotrexate, which is used to treat several conditions, such as arthritis
  • Any cephalosporin antibiotic, such as cefotiam, cefoxitin, or cefazolin, which is a medicine used to treat infections
  • Cyclosporine (Gengraf, Neoral, Sandimmune, and others), which is a medicine to suppress your immune system
  • Indomethacin, which is a non-steroidal anti-inflammatory drug (NSAID)
  • Digoxin (Lanoxin), which is a medicine used to treat irregular heartbeat and some types of heart failure
  • Any antihypertensive, which is a medicine that lower blood pressure
  • Any other diuretic, or water pill
Does Furosemide (Lasix) interact with other drugs you are taking?
Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much furosemide?

If you or someone else has used too much furosemide, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of furosemide?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

Drug Survey

Are you currently using Furosemide (Lasix)?

This survey is being conducted by the WebMD marketing sciences department.