I HAVE BEEN ON LISINOPRIL FOR ABOUT 1 AND A HALF YRS NOW AT 20 MG. A DAY.MY BLOOD PRESSURE WAS HIGH WHEN I WENT TO DR. LAST WEEK AND SHE ADDED HYDROCHLOROTHIAZIDE WITH IT .HOW LONG BEFORE I SEE A DROP IN BLOOD PRESSURE OR DO I NEED A DIFFERENT BP MEDICATION AS MAYBE IT IS NOT AS EFFECTIVE AS IT SHOULD BE SINCE I HAVE BEEN TAKING IT SO LONG??????????