Generic name: Furosemide.

Other brand names: SK-Furosemide.

Lasix is a loop diuretic. It increases the elimination of sodium and water through the kidneys.

Quick Facts About Lasix


Used to treat high blood pressure and other conditions requiring elimination of excess fluid, including congestive heart failure, cirrhosis of the liver, and kidney disease.

Lasix Dosage

Take exactly as prescribed — on a regular basis for maximum effectiveness. May take several weeks to observe the full effects. Continue taking even if symptoms subside.

  • Usual adult dose: For fluid retention — single dose of 20 to 80 milligrams, which may be repeated in 6 to 8 hours. Doctor may raise dose by 20 or 40 milligrams 6 to 8 hours after each successive dose. Maximum daily dose is 600 milligrams. For high blood pressure — 80 milligrams per day divided into 2 doses. Seniors — dose determined by individual needs.
  • Usual child dose: 2 milligrams per 2.2 pounds of body weight. Doctor may raise dose by I to 2 milligrams per 2.2 pounds. Doses are 6 to 8 hours apart, not to exceed 6 milligrams per 2.2 pounds.
  • Missed dose: take as soon as possible, unless almost time for next dose. In that case, do not take missed dose; go back to regular schedule. Do not double doses.

Lasix Side Effects

Overdose symptoms:

dehydration, dry mouth, excessive thirst, low blood pressure, muscle pain or cramps, weak or irregular heartbeat. If you suspect an overdose, immediately seek medical attention.

More common side effects: anemia, blood disorders, blurred vision, constipation, cramping, diarrhea, dizziness, dizziness upon standing, fever, headache, hearing loss, high blood sugar, hives, itching, loss of appetite, low potassium, muscle spasms, nausea, rash, reddish or purplish skin spots, resdessness, ringing in ears, sensitivity to light, skin eruptions, skin inflammation and flaking, stomach or mouth irritation, tingling or pins and needles, vertigo, vision changes, vomiting, weakness, yellow eyes and skin.

No known less common or rare Lasix side effects.


Inform your doctor before combining Lasix with:

aminoglycoside antibiotics such as Garamycin; aspirin; barbiturates such as phenobarbital; ethacrynic acid (Edecrin); indomethacin (Indocin); lithium (Lithonate); muscle relaxants such as Tubocurarine; narcotics such as Darvon and Percocet; nonsteroidal anti-inflammatory medications such as Advil and Naprosyn; norepinephrine (Levophed); other high blood pressure medications such as Vasotec and Aldomet; skeletal muscle relaxants such as succinyl-choline (Anectine); sucralfate (Carafate).

No known food/other substance interactions. 

Special Cautions

If pregnant or planning to become pregnant, inform your doctor immediately. Appears in breast milk; could affect a nursing infant.

For seniors, dose determined by individual needs.

Follow doctor’s instructions carefully for children.

  • If sensitive to or allergic to this or other diuretics, or if unable to urinate, should not take.
  • May cause potassium loss; symptoms include muscle weakness and rapid or irregular heartbeat. Doctor may prescribe potassium supplements or eating potassium-rich foods such as bananas, prunes, raisins, orange juice, and whole and skim milk.
  • Inform your doctor and use Lasix with caution if you have: diabetes, gout, kidney disease, liver disease, or lupus erythematosus.
  • Allergies to sulfa drugs may indicate allergy to Lasix.
  • Avoid nonprescription medications such as cold remedies and appetite suppressants if you have high blood pressure.
  • May experience sensitivity to sunlight.

Note: provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Lasix side effects, please contact your healthcare provider.