Before you start taking Lasix, talk to your doctor about:, All the medications you take, Your allergies, Your health history and current health problems, Your pregnancy or breastfeeding status, Dehydration, low blood pressure, and electrolyte abnormalities can occur with the use of Lasix., Patients who are allergic to sulfonamide medications should use Lasix with caution. All the medications you take, Your allergies, Your health history and current health problems, Your pregnancy or breastfeeding status