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PRECAUTIONS: Patients allergic to sulfa may also be allergic to furosemide because of a similarity in the chemical structure of the medications. Furosemide should be avoided in kidney failure. Even though furosemide is important in treating excess fluid accumulation in patients with cirrhosis, sudden loss of fluid and electrolytes in these patients can worsen kidney function and even cause the patient to go into a coma. Furosemide can cause lowering of blood potassium, sodium, and magnesium levels. Low potassium and magnesium levels can lead to heart rhythm abnormalities, especially in patients already taking digoxin (Lanoxin). Please visit the digoxin (Lanoxin) site for further information.
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Furosemide reduces the kidney excretion of lithium... Furosemide may impair kidney function when administered together with aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs).