Lasix (furosemide) is a loop diuretic (water pill) that prevents your body from absorbing too much salt, allowing the salt to instead be passed in your urine.
Lasix treats fluid retention (edema) in people with congestive heart failure, liver disease, or a kidney disorder such as nephrotic syndrome. This medication is also used to treat high blood pressure (hypertension).
You should not use Lasix if you are unable to urinate.
Before using Lasix, tell your doctor if you have kidney disease, enlarged prostate, urination problems, cirrhosis or other liver disease, an electrolyte imbalance, high cholesterol, gout, lupus, diabetes, or an allergy to sulfa drugs.
Tell your doctor if you have recently had an MRI (magnetic resonance imaging) or any type of scan using a radioactive dye that is injected into your veins. Do not take more of this medication than is recommended. High doses of Lasix may cause irreversible hearing loss. If you are being treated for high blood pressure, keep using this medication even if you feel fine. High blood pressure often has no symptoms.
Get emergency medical help if you have any of these signs of an allergic reaction to Lasix: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using Lasix and call your doctor at once if you have a serious side effect such as:
- ringing in your ears, hearing loss;
- itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
- severe pain in your upper stomach spreading to your back, nausea and vomiting;
- weight loss, body aches, numbness;
- swelling, rapid weight gain, urinating less than usual or not at all;
- chest pain, new or worsening cough with fever, trouble breathing;
- pale skin, bruising, unusual bleeding, feeling light-headed, rapid heart rate, trouble concentrating;
- low potassium (confusion, uneven heart rate, leg discomfort, muscle weakness or limp feeling);
- low calcium (tingly feeling around your mouth, muscle tightness or contraction, overactive reflexes);
- headache, feeling unsteady, weak or shallow breathing; or
- severe skin reaction — fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Less serious Lasix side effects may include:
- diarrhea, constipation, stomach pain;
- dizziness, spinning sensation; or
- mild itching or rash.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.