Magnesium Supplements Can Interact With Antibiotics and Bone-Loss Medications

Taking magnesium supplements alongside certain medications, including antibiotics and bone-loss drugs, can reduce the effectiveness of those drugs, experts say. Magnesium is one of the most popular supplements, often taken to promote sleep, but it carries a risk of interactions with other supplements and medications.

Magnesium is an essential mineral that the body needs to meet specific physiological needs. It is essential to producing adenosine triphosphate (ATP), a cellular energy source, and contributes to more than 300 chemical processes in the body. It regulates blood pressure and blood sugar levels, supports muscle function, plays a role in energy production and nerve function, and boosts bone health. Magnesium naturally occurs in nuts, seeds, beans, grains and fruit, and most people get enough from a balanced diet. However, people with certain gastrointestinal conditions may have a magnesium deficiency requiring a boost from supplements.

A drug interaction occurs when a medication works differently than it would otherwise due to another medication or supplement, a food or beverage consumed, or a patient's existing health condition. Risks range from more severe side effects to changes in how the body absorbs a drug or supplement, reducing its effectiveness. Because dietary supplements are not regulated by the Food and Drug Administration the same way food and medicine are, the FDA recommends talking to a health care provider before adding a new supplement. The Cleveland Clinic likewise recommends talking to a health care provider before taking a magnesium supplement.

Too much magnesium can cause diarrhea, nausea, lethargy, impaired kidney function and low blood pressure. The supplement form carries a risk of interactions because the dose is isolated and concentrated.

Common medications that may interact with magnesium supplements include antibiotics and bisphosphonates. Tetracyclines, an antibiotic class used to treat acne, chlamydia and traveler's diarrhea, and fluoroquinolones, used for urinary tract and respiratory infections, can be less effective when magnesium affects how the body absorbs them. The antibiotics can also reduce how much magnesium the body absorbs. Bisphosphonates, often prescribed for osteoporosis and other bone density conditions, are very poorly absorbed under the best of circumstances; they are best taken with water on an empty stomach. Having magnesium present at the same time could essentially eliminate bisphosphonate absorption.