Arrhythmias (Heart Rhythm Disturbances) and Magnesium

Supplementing with magnesium may help treat some types of arrhythmias. The mineral tends to stabilize the heart, and intravenous infusions of magnesium are sometimes given to people in cardiac intensive care.

In addition, magnesium deficiency can sometimes result from the use of some drugs. The drug digoxin appears to sensitize the heart to magnesium deficiency. People with congestive heart failure (CHF) are likely to use both digoxin and loop diuretics, a type of diuretic that depletes magnesium, and the net result can be cardiac arrhythmias.^5-8

Magnesium may have many beneficial effects on the heart. Our bodies need mangesium for healthy functioning, including muscle relaxation, blood clotting, and the manufacture of ATP (adenosine triphosphate, the body's main energy molecule). In addition, some patients on medications such as digoxin and certain diuretics develop magnesium deficiencies that can cause or worsen arrhythmias. Supplementing with magnesium can treat some arrhythmias by correcting this mineral deficit.

Also, magnesium has been called "nature's calcium channel blocker." The idea refers to magnesium's ability to block calcium from entering muscle and heart cells. A group of prescription heart medications work in a similar way, although much more powerfully. This may be the basis for some of magnesium's effects when it is taken as a supplement in fairly high doses.

Read more details about Magnesium.

A 6-month, double-blind, placebo-controlled study of 170 people did not find oral magnesium effective for maintaining normal heart rhythm in people with a tendency to develop atrial fibrillation.³ However, one small double-blind, placebo-controlled study found that magnesium supplements reduced episodes of ventricular arrhythmia in people with congestive heart failure (CHF).⁴

A typical supplemental dosage of magnesium goes up to 600 mg daily. One study that demonstrated the benefits of magnesium for coronary artery disease involved daily doses of 730 mg.⁹

• Integrative MD
• Naturopathic doctor
• Clinical nutritionist or registered dietitian

Safety Issues

The US government has set the following upper limits for use of magnesium supplements:

• Children

• 1-3 years: 65 mg

• 4-8 years: 110 mg

• Adults: 350 mg

• Pregnant or Nursing Women: 350 mg

In general, magnesium appears to be quite safe when taken at or below recommended dosages. The most common complaint is loose stools. However, people with severe kidney or heart disease should not take magnesium (or any other supplement) except on the advice of a physician. Maximum safe dosages have not been established for young children. There has been one case of death caused by excessive use of magnesium supplements in a developmentally and physically disabled child. ¹ Pregnant or nursing women should not exceed the nutritional dosages presented under Requirements/Sources .

If taken at the same time, magnesium can interfere with the absorption of antibiotics in the tetracycline family, ² and, possibly, the drug nitrofurantoin . ³ Also, when combined with oral diabetes drugs in the sulfonylurea family, magnesium may cause blood sugar levels to fall more than expected. ⁴

Interactions You Should Know About

If you are taking:

• Potassium supplements , manganese , loop and thiazide diuretics , oral contraceptives , estrogen-replacement therapy , cisplatin, digoxin , or medications that reduce stomach acid: You may need extra magnesium.

• Antibiotics in the tetracycline family or nitrofurantoin (Macrodantin): You should separate your magnesium dose from doses of these medications by at least 2 hours to avoid absorption problems.

• Oral diabetes medications in the sulfonylurea family (Tolinase, Micronase, Orinase, Glucotrol, Diabinese, DiaBeta): Work closely with your physician when taking magnesium to avoid hypoglycemia.

• Amiloride : Do not take magnesium supplements except on medical advice. ⁵

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2. Tatro D, ed. Drug Interaction Facts. St. Louis, MO: Facts and Comparisons; 1999.
3. Naggar VF, Khalil SA. Effect of magnesium trisilicate on nitrofurantoin absorption. Clin Pharmacol Ther. 25(6):857-63.
4. Drug Evaluations Annual. Vol 2. Milwaukee, WI: American Medical Association; 1994.
5. Rudnicki M, Frölich A, Rasmussen WF, McNair P. The effect of magnesium on maternal blood pressure in pregnancy-induced hypertension. A randomized double-blind placebo-controlled trial. Acta Obstet Gynecol Scand. 70(6):445-50.

3. Frick M, Darpo B, Ostergren J, et al. The effect of oral magnesium, alone or as an adjuvant to sotalol, after cardioversion in patients with persistent atrial fibrillation. Eur Heart J. 2000;21:1177-1185.
4. Bashir Y, Sneddon JF, Staunton A, et al. Effects of long-term oral magnesium chloride replacement in congestive heart failure secondary to coronary artery disease. Am J Cardiol. 1993;72:1156-1162.
5. Martin BJ, Milligan K. Diuretic-associated hypomagnesemia in the elderly. Arch Intern Med. 1987;147:1768-1771.
6. Cohen L, Kitzes R. Magnesium sulfate and digitalis-toxic arrhythmias. JAMA. 1983;249:2808-2810.
7. Toffaletti J. Electrolytes, divalent cations, and blood gases (magnesium). Anal Chem. 1991;63:192R-194R.
8. Whang R, Oei TO, Watanabe A. Frequency of hypomagnesemia in hospitalized patients receiving digitalis. Arch Intern Med. 1985;145:655-656.
9. Shechter M, Bairey Merz CN, Stuehlinger HG, et al. Effects of oral magnesium therapy on exercise tolerance, exercise-induced chest pain, and quality of life in patients with coronary artery disease. Am J Cardiol. 2003;91:517-521.