Calcium channel blockers help reduce blood pressure by preventing calcium from entering the muscle cells in the walls of the heart and blood vessels, which causes them to be relaxed, according to Mayo Clinic. Their relaxation means that the blood vessels are more open.
Some calcium channel blockers have another positive effect in that they slow the heart rate, which also helps reduce blood pressure as well as helping prevent irregular heart rate, says Mayo Clinic. Calcium channel blockers are used to treat a range of conditions besides high blood pressure, including chest pains, the complications of brain aneurysms, migraines and some circulatory conditions. For many people, calcium channel blockers are not the first prescriptions given by doctors because other medications, such as diuretics and beta blockers, are more effective at reducing blood pressure. This depends partly on heredity, however, and calcium channel blockers are likely to be more effective in certain racial groups.
Calcium channel blockers have side effects in many patients, according to Mayo Clinic. These include constipation, headache, rapid heartbeat, dizziness, rash, fatigue, flushing, nausea and swelling in the lower extremities. Patients on some calcium channel blockers should not eat grapefruit, as the fruit can have chemical interactions with the medication.