Medically reviewed by Drugs.com. Last updated on Mar 5, 2021.
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 and dosage interval must be adjusted to the individual patient's needs .
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Cardiovascular Agent
Pharmacologic Class: Diuretic, Loop
Uses for Lasix
Furosemide belongs to a group of medicines called loop diuretics (also known as water pills). Furosemide is given to help treat fluid retention (edema) and swelling that is caused by congestive heart failure, liver disease, kidney disease, or other medical conditions. It works by acting on the kidneys to increase the flow of urine.
Furosemide is also used alone or together with other medicines to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.
This medicine is available only with your doctor's prescription.
Before using Lasix
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of furosemide in children. However, premature babies are more likely to have unwanted effects on the kidney, which may require caution in patients receiving furosemide.
Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of furosemide in the elderly. However, elderly patients are more likely to have age-related liver, kidney, or heart problems, which may require caution and an adjustment in the dose for patients receiving furosemide.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Amikacin Liposome
- Amtolmetin Guacil
- Arsenic Trioxide
- Chloral Hydrate
- Choline Salicylate
- Ethacrynic Acid
- Flufenamic Acid
- Mefenamic Acid
- Niflumic Acid
- Nimesulide Beta Cyclodextrin
- Salicylic Acid
- Sodium Salicylate
- Tiaprofenic Acid
- Tolfenamic Acid
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Other medical problems
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:
- Allergy to sulfa drugs (e.g., sulfamethoxazole, sulfasalazine, sulfisoxazole, Azulfidine®, Bactrim®, Gantrisin®, or Septra®) or
- Anemia or
- Bladder problem with urinating or
- Dehydration or
- Diabetes mellitus or
- Gout or
- Hearing problems or
- Hyperuricemia (high uric acid in the blood) or
- Hypocalcemia (low calcium in the blood) or
- Hypochloremic alkalosis (low chlorine in the blood) or
- Hypokalemia (low potassium in the blood) or
- Hypomagnesemia (low magnesium in the blood) or
- Hyponatremia (low sodium in the blood) or
- Hypotension (low blood pressure) or
- Hypovolemia (low blood volume) or
- Liver disease, severe (e.g., cirrhosis) or
- Systemic lupus erythematosus (SLE) or
- Tinnitus (ringing in the ears) or
- Trouble urinating (caused by bladder emptying disorders, enlarged prostate, narrow urethra)—Use with caution. May make these conditions worse.
- Anuria (not able to pass urine)—Should not be used in patients with this condition. .
- Hypoproteinemia (low protein in the blood) from a kidney problem or
- Radiocontrast nephropathy (kidney problem)—May cause side effects to become worse.
- Kidney disease, severe—Use with caution. The effects may be increased because of slower removal of the medicine from the body.
Proper use of Lasix
This section provides information on the proper use of a number of products that contain furosemide. It may not be specific to Lasix. Please read with care.
Take this medicine exactly as directed by your doctor to benefit your condition as much as possible. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.
Many patients who have high blood pressure will not notice any symptoms of the condition. In fact, most patients feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well.
In addition to using this medicine, treatment of your high blood pressure may include weight control and changes in the types of foods you eat, especially foods high in sodium (salt) or potassium. Your doctor will tell you which of these are most important for you. You should check with your doctor before changing your diet.
This medicine will not cure your high blood pressure, but it does help control it. You must continue to take it as directed if you expect to lower your blood pressure and keep it down. You might have to take high blood pressure medicine for the rest of your life. If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, strokes, or kidney disease.
Measure the oral liquid with a marked measuring spoon, oral syringe, or medicine cup.
If you are taking sucralfate (Carafate®), take this medicine 2 hours before or 2 hours after taking furosemide. It may keep furosemide from working properly.
The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage forms (oral solution or tablets):
- For edema:
- Adults—At first, 20 to 80 milligrams (mg) once a day as a single dose or divided and given twice per day. Your doctor may adjust your dose as needed.
- Children—Dose is based on body weight and must be determined by your doctor. The starting dose is usually 2 milligrams (mg) per kilogram (kg) of body weight per day as a single dose. Your doctor may adjust your dose as needed. However, the dose is usually not more than 6 mg per kg of body weight per day.
- For high blood pressure:
- Adults—At first, 40 milligrams (mg) two times per day. Your doctor may adjust your dose as needed.
- Children—Use and dose must be determined by your doctor.
- For edema:
If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions while using Lasix
It is very important that your doctor check the progress of you or your child at regular visits to make sure this medicine is working properly. Blood or urine tests may be needed to check for unwanted effects.
Using this medicine while you are pregnant may cause your unborn baby to be bigger than normal. If you think you have become pregnant while using this medicine, tell your doctor right away.
This medicine may cause you or your child to lose more potassium from your body than normal (hypokalemia). This is more likely to occur if you have liver disease (e.g., cirrhosis), or if you are using this medicine together with steroids (cortisone-like medicines), adrenocorticotropic hormone (ACTH), large amounts of licorice, or laxatives for a long time. Tell your doctor if you become sick with severe or continuing nausea, vomiting, or diarrhea, and drink fluids to prevent getting dehydrated. Check with your doctor right away if you have dry mouth, increased thirst, muscle cramps, or nausea or vomiting.
Dizziness, lightheadedness, or fainting may occur, especially when you get up suddenly from a lying or sitting position. Getting up slowly may help. If the problem continues or gets worse, check with your doctor.
Stop using this medicine and check with your doctor right away if you have a sudden decrease in hearing or loss of hearing. You may also have dizziness or ringing in the ears. Tell your doctor if you have a feeling of constant movement of self or surroundings or a sensation of spinning.
This medicine may cause an increase in blood sugar levels. If you are diabetic and notice a change in the results of your blood or urine sugar tests, check with your doctor.
This medicine may make your skin more sensitive to sunlight. Use a sunscreen, hat, and protective clothing when you are outdoors. Avoid sunlamps and tanning beds.
Make sure any doctor or dentist who treats you knows that you are using this medicine. This medicine may affect the results of certain medical tests.
Do not take other medicines unless they have been discussed with your doctor. This especially includes prescription or nonprescription (over-the-counter) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems.
Lasix side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
- Chest pain
- cough or hoarseness
- general feeling of tiredness or weakness
- lower back or side pain
- painful or difficult urination
- shortness of breath
- sore throat
- sores, ulcers, or white spots on the lips or in the mouth
- swollen or painful glands
- tightness in the chest
- unusual bleeding or bruising
- unusual tiredness or weakness
Incidence not known
- Back or leg pains
- black, tarry stools
- bleeding gums
- blistering, peeling, or loosening of the skin
- blood in the urine or stools
- blurred vision
- burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
- changes in skin color, pain, tenderness, or swelling of the foot or leg
- clay-colored stools
- cloudy urine
- cold sweats
- continuing ringing or buzzing or other unexplained noise in the ears
- coughing up blood
- cracks in the skin
- darkened urine
- difficulty breathing
- dizziness, faintness, or lightheadedness when getting up from a lying or sitting position
- dry mouth
- fast heartbeat
- flushed, dry skin
- fruit-like breath odor
- greatly decreased frequency of urination or amount of urine
- hearing loss
- increased hunger
- increased thirst
- loss of appetite
- nausea or vomiting
- pain in the joints or muscles
- pains in the stomach, side, or abdomen, possibly radiating to the back
- pale skin
- pinpoint red spots on the skin
- red, irritated eyes
- red, swollen skin
- skin rash
- spots on your skin resembling a blister or pimple
- swelling of the feet or lower legs
- trouble breathing with exertion
- unusual weight loss
- vomiting of blood
- yellow eyes or skin
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
- Decreased urination
- increase in heart rate
- irregular heartbeat
- mood changes
- muscle cramps
- numbness, tingling, pain, or weakness in the hands, feet, or lips
- rapid breathing
- sunken eyes
- weak pulse
- weakness and heaviness of the legs
- wrinkled skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Incidence not known
- Feeling of constant movement of self or surroundings
- hives or welts
- increased sensitivity of the skin to sunlight
- muscle spasm
- redness or other discoloration of the skin
- sensation of spinning
- severe sunburn
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Frequently asked questions
- Are losartan and losartan potassium the same drug or two different ones?
- How long after taking Lasix would you expect to urinate?
- Can you take Lasix for weight loss?
More about Lasix (furosemide)
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Patient Tips
- Drug Images
- Drug Interactions
- Compare Alternatives
- Pricing & Coupons
- En Español
- 49 Reviews
- Generic Availability
- Drug class: loop diuretics
Related treatment guides
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.