Negative Magnesium Side Effects Can Be Prevented
Magnesium side effects have resulted from excessive use of supplements but not from dietary intake. People with kidney disease are more likely to experience side effects.
The U.S. Food and Nutrition Board (FNB) of the Institute of Medicine has set the tolerable upper intake level (UL) for magnesium at 350 mg/day.
This upper limit represents the highest level of daily magnesium intake from supplements that is likely to pose no risk of diarrhea or gastrointestinal disturbance in almost all individuals.
However, people with renal impairment (kidney disease) are at higher risk of side effects from supplements and will generally prefer foods high in magnesium.
The initial symptom of excess magnesium supplementation is diarrhea—a well-known side effect of magnesium as it is often used as a laxative. People with impaired kidney function may experience side effects from even the moderate amount of magnesium that is found in laxatives and antacids. Elevated blood levels of magnesium (hypermagnesemia) may result in a fall in blood pressure.
Continued side effects in the form of toxicity include lethargy, confusion, disturbances in normal cardiac rhythm and deterioration of kidney function resulting from low blood pressure. If the toxicity progresses, muscle weakness and difficulty breathing may occur and severe hypermagnesemia may result in cardiac arrest.