Lasix (Furosemide) is a strong "water pill" (diuretic). Using too much of this drug can lead to serious water and mineral loss. Promptly notify your doctor if you become very thirsty, have a dry mouth, become confused, or develop muscle cramps/weakness. 
Lsix is a diuretic. Diuretics are referred to as "water pills" because they decrease the amount of water retained in the body by increasing urination. Diuretics are used to treat edema (fluid retention and swelling especially of the hands and feet caused by heart failure and other diseases) and hypertension.