Furosemide (Lasix) is a potent loop diuretic that works by preventing your body from absorbing too much salt and this way treating fluid retention associated with heart failure and other diseases. Furosemide can be also used for the treatment of high blood pressure. In that case you will need to keep taking it even if you feel fine. Never take more of Furosemide than prescribed, even if you missed a dose. If your two doses happen to be too close in time because you forgot to take one of them - avoid taking a double dose, as it is not likely to increase the effectiveness of Furosemide. The following symptoms may indicate Furosemide overdose: loss of appetite, weakness, ringing in your ears, dizziness, fainting, confusion, and lightheadedness. Seek emergency medical help if you get any of those. Serious side effects are quite rare and need to be reported to your health care provider as soon as you notice them. They are not going to go away on their own as mild side effects you may develop, such as constipation, blurred vision, tingly feeling, burning, diarrhea, dizziness, headache, and stomach pain. In case of vomiting, having jaundice, peeling skin rash, restlessness, clay-colored stools, easy bruising, dry mouth, unusual weakness, or dark urine, seek emergency medical help.