Is it true that calcium supplements may interact with blood pressure medications?

Answer From Sheldon G. Sheps, M.D.

Yes. In large amounts, calcium supplements may interact with some blood pressure medications. Interactions may occur with:

  • Thiazide diuretics. Taking large amounts of calcium carbonate with thiazide diuretics — such as chlorothiazide (Diuril), hydrochlorothiazide (Microzide) and indapamide — can increase the risk of milk-alkali syndrome, a serious condition.

    In general, avoid taking large amounts of calcium carbonate (supplements and food sources combined) daily if you're taking a thiazide diuretic (also referred to as water pills).

    If you take calcium supplements while taking a thiazide diuretic, talk to your doctor about the appropriate dose, and have your blood pressure and calcium levels checked.

  • Calcium channel blockers. When given through an intravenous (IV) line, calcium may decrease the effects of calcium channel blockers, such as nifedipine (Adalat CC, Afeditab CR, Procardia), verapamil (Verelan, Calan), diltiazem (Cardizem, Cartia XT, others) and others. In fact, IV calcium is used to help reverse calcium channel blocker overdoses.

    There's no evidence that oral calcium supplements interfere with calcium channel blockers. To be safe, check your blood pressure regularly if taking calcium channel blockers and calcium supplements at the same time.

Calcium supplements don't appear to interact with other commonly prescribed blood pressure medications, such as:

  • Beta blockers bisoprolol (Ziac), propranolol (Inderal, Innopran XL) and others
  • Angiotensin-converting enzyme (ACE) inhibitors, such as captopril, lisinopril (Prinivil, Zestril) and others
  • Angiotensin II receptor blockers, such as losartan (Cozaar), valsartan (Diovan) and others
  • Renin inhibitors, such as aliskiren (Tekturna)

Talk to your doctor if you take high blood pressure medications and calcium supplements and are concerned about interactions.

Jan. 09, 2019