Get emergency medical help if you have signs of an allergic reaction to furosemide (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning in your eyes, skin pain, red or purple skin rash that spreads and causes blistering and peeling).
To make sure this medicine is safe for you, tell your doctor if you have:
a light-headed feeling, like you might pass out;
ringing in your ears, hearing loss;
muscle spasms or contractions;
pale skin, easy bruising, unusual bleeding;
high blood sugar - increased thirst, increased urination, dry mouth, fruity breath odor;
kidney problems - little or no urination, swelling in your feet or ankles, feeling tired or short of breath;
signs of liver or pancreas problems - loss of appetite, upper stomach pain (that may spread to your back), nausea or vomiting, dark urine, jaundice (yellowing of the skin or eyes); or
signs of an electrolyte imbalance - dry mouth, thirst, weakness, drowsiness, feeling jittery or unsteady, vomiting, irregular heartbeats, fluttering in your chest, numbness or tingling, muscle cramps, muscle weakness or limp feeling.
Common furosemide side effects may include:
diarrhea, constipation, loss of appetite;
numbness or tingling;
headache, dizziness; or
blurred vision.
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.
 Furosemide side effects (more detail)
