Hello Welcome to HCM Thanks for posting your query in HCM. Bendroflumethiazide is a thiazide diuretic. It works by helping the kidneys eliminate fluid from the body. Side effects of the drug include dry mouth; excessive urination followed by a decrease in amount of urine; muscle cramps; severe lightheadedness, especially upon standing; weak or irregular heartbeat. As the patient is on this diuretic,it has caused a lot of water loss from the body that has lead to hypotension that is low blood pressure and compensatory high heart rate. Also correct his anemia by giving iron transfusions. So,i would advise him to lower the dose of the drug he is taking after consulting his treating doctor. Hope you are happy with the answer. Thank you