Diltiazem should be taken as prescribed by your doctor. It should be taken at the same time each day. The pill or capsule should be swallowed whole with water, either on an empty stomach or with food as your doctor or pharmacist recommends. Do not chew or crush the medication. If you have difficulty swallowing capsules, check with your doctor or pharmacist to find out whether you can empty the contents of a capsule into some applesauce to make the medicine easier to swallow. Diltiazem can also be given as an injection to treat heart rhythm disturbances. Diltiazem injection is usually administered by a doctor or a healthcare professional.