Brand Name:Apo-Furosemide, Furosemide Injection, Lasix, Lasix Special

Prescription needed: Yes

What is this drug used for?

Furosemide is a powerful, fast-acting water pill (diuretic) that is typically used to decrease or prevent fluid build-up that is associated with congestive heart failure and kidney or liver problems. It is also sometimes used to treat high blood pressure.

Is there any reason not to take this drug?

Do not take this medication if you are allergic to furosemide or bumetanide. Tell your doctor if you have or have ever had:

  • gout
  • pancreatitis
  • low blood pressure (e.g. hypotension)
  • difficulty going to the bathroom (e.g. urinary incontinence)
  • problems with your cholesterol or triglycerides
  • problems with your kidney or liver
  • systemic lupus erythematosus
  • high or low levels of sodium, potassium, magnesium or calcium in your blood
  • an allergic reaction to sulfa-like drugs (e.g. Septra, sulfamethoxazole) – you may have an increased risk to an allergic reaction but overall, your risk is likely minimal
  • problems with hearing
  • high blood sugar or diabetes

What about possible side effects?

The most common side effects are:

  • low levels of sodium, potassium, calcium or magnesium (your doctor may perform blood tests to check on these while you are taking the drug)
  • high levels of uric acid
  • going to the bathroom more often
  • feeling dizzy or lightheaded
  • low blood pressure

These side effects are usually related to dose, the use of other medications and other factors (e.g. older age, other medical conditions). As well, some of these side effects may go away with time. Talk to your doctor or pharmacist about whether you have any risk factors that may make you more sensitive to these side effects. Contact your doctor if these symptoms continue or become worse.

Other side effects include:

  • increased sensitivity to the sun (it is recommended that you use sunscreen and wear protective clothing)
  • muscle cramps or pain
  • rash
  • loss of hearing or ringing in the ears - rare; if this occurs, it is usually with very high doses, call your doctor immediately
  • problems with the kidney - if occurs, usually in higher doses and with other risk factors

This is not a complete list of side effects. If you are concerned about these or other unusual symptoms while taking this medication, ask your doctor and/or pharmacist for more information and advice.

What if I am taking other drugs?

Always provide your doctor with a list of all other drugs you are taking (including over-the-counter medications and herbal/natural products) as they may interact with and/or may change the safety or effectiveness of either drug. Tell your doctor specifically if you are taking any of these drugs as these are the most common interactions and he/she may need to make changes or monitor you more closely:

  • ACE-inhibitors (e.g. enalapril, ramipril, lisinopril) or Angiotensin Receptor Antagonists (e.g. losartan) - may increase your chances for low blood pressure
  • digoxin - may increase chances for side effects; talk to your doctor about whether you need to take potassium supplements
  • lithium - may increase the amount of lithium in the blood
  • other water pills - may increase your chances for some side effects
  • other medications to treat high blood pressure - may increase your chances for experiencing low blood pressure
  • ASA and other anti-inflammatories (e.g. ibuprofen, voltaren, diclofenac) (e.g. ibuprofen, naproxen, voltaren) – may influence how well furosemide can work
  • if you are taking this drug to treat high blood pressure, be careful of certain over-the-counter medicines that may increase your blood pressure - these include some cough and cold medicines; ask your doctor or pharmacist for more information

This is not a complete list of drug interactions. Ask your doctor or pharmacist to review your list of medications.

Other information:

Warning: Furosemide is a very strong water pill which, if taken in excessive amounts, can lead to the loss of water and electrolytes such as sodium, potassium and magnesium from the body. This risk may be greater with certain medical conditions and medications. Your physician will be checking you closely and will likely order occasional blood tests.

Sun-Protection: Since your skin may burn more easily while taking this medication, it is recommended that you use sunscreen and wear protective clothing to decrease the chance of this happening.

Children: Lower doses are necessary.

Seniors: Are usually more sensitive to the effects of this medication. Lower doses should be used in the beginning and you should be monitored more closely for side effects (e.g. blood levels of sodium, potassium, dizziness, incontinence, low blood pressure).

Pregnant women: Talk to your doctor.

Women who are nursing: Talk to your doctor.

People who drive or operate machinery: Should not do so until they know how this drug will affect them personally; may cause you to feel faint or dizzy.

Alcohol: Not advised as it could contribute to dehydration.

Overdose: If you experience any unusual reactions, or if you seriously exceed the recommended dosage, call your doctor or 911.

Stopping the drug: This drug is sometimes only needed periodically and can be stopped now and again. Other times, it needs to be taken every day to prevent fluids from building up in the body. Talk to your doctor before you stop taking this drug. Stopping the drug may cause your symptoms (e.g. swollen ankles) to return.

If you miss a dose: Take the missed dose as soon as you remember it. If it is almost time for the next dose, take the missed dose and skip the next dose. Never take a double dose of this medicine.

Storage conditions: Closed container; cool, dry location away from excess moisture (not in the bathroom) and direct light; always out of reach of children.

Dietary precautions: Furosemide may decrease the amount of sodium, potassium, calcium and magnesium in your body. Your doctor may recommend a supplement or suggest you eat more fruit and vegetables.