The calcium channel blockers are a group of medications that have been used for treating a variety of cardiovascular disorders such as high blood pressure. These medications alter the movement of calcium ions into muscle cells of blood vessels. This effect can sometimes prevent blood vessel changes, which are involved in migraine and cluster headache.

Calcium channel blockers have not been approved by the F.D.A. for prevention of migraine, but some research studies with verapamil have shown it to be effective in prevention of migraine and cluster headache.

Verapamil is the most widely studied calcium channel blocker and in general is the drug of first choice within this group of medicines. Unlike beta blockers, calcium channel blockers may be used in patients with asthma and other respiratory diseases. Some researchers have suggested that calcium channel blockers may be more effective than beta blockers in migraine with aura (classical migraine) and in complicated migraine. Verapamil is also helpful in treating cluster headache cycles, sometime requiring very high daily doses.

Constipation and low blood pressure are common side effects with calcium channel blockers.