Lasix 40mg tablet is a diuretic medication that helps in removing excess water and salt from the body through urine. The active ingredient in Lasix is furosemide, which is a loop diuretic. It is used to treat edema (swelling) caused by congestive heart failure, liver disease, kidney disease, and other medical conditions. It can also be used to treat high blood pressure (hypertension) when other medications have not been effective. Lasix works by increasing urine output, reducing the amount of fluid in the body, and lowering blood pressure. The usual recommended dose of Lasix is 20mg to 80mg per day, depending on the patient's condition and response to treatment. Lasix tablets are usually taken once or twice daily with or without food. It is important to take the medication as prescribed by the doctor and not to change the dose or stop the medication without consulting with the doctor. Possible side effects of Lasix include dehydration, low blood pressure, electrolyte imbalance, dizziness, headache, blurred vision, ringing in the ears, nausea, vomiting, and diarrhea.