Like beta-blockers, calcium channel blockers are a class of medications traditionally used to treat cardiovascular conditions such as hypertension and irregular heart rhythms. They block the absorption of calcium into the heart muscle and vascular system, “relaxing” the cardiovascular system and increasing blood flow to the heart. They are also thought to regulate serotonin levels, which may explain their efficacy in migraine prevention.

Some studies have shown that verapamil (Calan) and nifedipine (Procardia) may be useful in the prevention of migraine. Other calcium channel blockers, such as nimodipine, have demonstrated conflicting results. None of these drugs are FDA approved for use in migraine prevention.

Potential side effects of calcium channel blockers include constipation, edema (swelling), and low blood pressure causing dizziness or even fainting.

If you are prescribed a calcium channel blocker, you should not take it with grapefruit or grapefruit juice because these decrease the efficacy of the drug. Alcohol should also be avoided, as it can magnify some side effects and interfere with the activity of the drug.

People with certain preexisting health conditions should use calcium channel blockers under a doctor's recommendation and close supervision. Because there are more effective migraine prophylactics available, your doctor may recommend that you avoid calcium channel blockers completely if you have very low blood pressure, heart failure, or impaired liver or kidney function.

Pregnant women should avoid the use of calcium channel blockers because of the risk of birth defects.