Diltiazem is a medication that is used to treat excessive blood pressure, chest discomfort, and some cardiac rhythm problems. It may improve your capacity to exercise and reduce the frequency with which you get angina episodes. Diltiazem is referred to as a calcium channel blocker. It reduces heart rate by relaxing blood arteries in the body and heart. Blood may flow more easily, and your heart has to work less hard to pump it. Diltiazem tablets are available in multiple dosages of 30mg, 60mg, 100mg, 120mg, 300mg, and 500mg. Diltiazem has some mild side effects like headaches, weakness, vomiting, and diarrhea.