Ask the doctor: Do calcium supplements counteract calcium-channel blockers?

Ask the doctor

Do calcium supplements counteract calcium-channel blockers?

Published: December, 2008

Q. My doctor started me on a calcium-channel blocker for high blood pressure. I also take a daily calcium supplement for my bones. Will that counteract the drug's effect?

A. You don't need to worry about taking a daily calcium supplement with a calcium-channel blocker. While high doses of intravenous calcium are sometimes used to reverse an overdose of a calcium-channel blocker, the amount of calcium in a daily supplement isn't enough to interfere with the drug's ability to lower blood pressure. In fact, in some people, an oral calcium supplement actually lowers blood pressure around one or two points. Since the effect is so small, oral calcium isn't recommended for treating high blood pressure.

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