Furosemide (Generic Name)
Other Names: Lasix®

Dosage form

Oral tablets: 20 mg, 40 mg, 80 mg

About this drug

Furosemide (fyoor-OH-sa-mide) is used to treat and prevent too much fluid in the body. It works by making you pass more urine. It is a “water pill” (loop diuretic). It is also a blood pressure lowering agent (anti-hypertensive).

Side effects

Common side effects are:

  • Decreased potassium level
  • Increased sensitivity to sunlight
  • Passing more urine at night (nocturia)
  • Dizziness or lightheadedness. Be careful while taking this drug. Driving and using machines can be dangerous if you are not alert.

Rare side effects include:

  • Fever
  • Chills
  • Lower back pain
  • Ringing in the ears
  • Nausea
  • Dry mouth
  • Extreme thirst
  • Increased heart rate
  • Tiredness

If any of these side effects becomes severe or bothers you, call your doctor. Do not take over-the-counter medicine for your symptoms.

Drug interactions

Tell your doctor or pharmacist about any prescription medicine, over-the-counter medicine, or herbal products that you are taking. He or she will check for interactions.

If you miss a dose

If you miss a medicine dose, take it as soon as you remember. If it is within 2 hours of the
time for your next dose, skip the missed dose. Take your next dose at its scheduled time, and continue your usual dosing schedule.

Do not “double up” on doses to catch up.

Potassium supplement

Your doctor may have you take a potassium supplement to prevent a decrease in your potassium levels.  

How to take this medicine

If your prescription says to take this medicine once daily, take it in the morning. If you’re to take more than 1 dose each day, take the last dose before 6 p.m. This will help keep you from waking in the middle of the night to use the bathroom.


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