Studies have shown that verapamil may be effective in the preventive treatment of migraine and cluster headache patients.

Verapamil is a calcium blocker that may work by preventing the constriction of the blood vessels prior to the migraine attack. However, recent genetic studies have suggested that calcium channels in nerve cells may not function normally in migraine. Verapamil is commonly used for blood pressure and heart conditions. It takes at least four to six weeks for it to become effective in treating migraine. Side effects such as ankle swelling, constipation, and fatigue are common.