I just came across your WONDERING about Diltiazem. I took Diltiazem for so many years I can not truthfully tell you how many. Rough guess, 10 plus years. I tolerated it extremely well. Never any problems to my knowledge. I fell & broke my rt. hip in April. A new Doctor took me off Diltiazem in the hospital. Now my new primary care Doctor has me on Lisinopril 2 per day. I asked if I could go back on Diltiazem & he told me no because it would not do for my heart what he wants it to do. Also, on Metoprolol half tab. 2x day. To slow my heart down. Best of luck to you from Booarang12