Magnesium stearate is a chemical with different medicinal and industrial uses. One of the most common, according to the United States National Library of Medicine Toxicology Data Network, is in tablets, particularly in nutritional supplements as a lubricant to prevent the adherence of particles of tablet powder to the press machine. It is also used in baby powder, food packaging and in cosmetics, and as an ingredient in foods to prevent caking. Magnesium stearate is essentially metallic magnesium bound to a fatty acid. Its use may be associated with some side effects.
Renal Complications Demonstrated in Laboratory Animals
The United States National Library of Medicine Toxicology Data Network (TOXNET) lists the toxic effects that occurred when feeding laboratory rats with magnesium stearate. Some rats developed urinary stones and others produced a condition known as nephrocalcinosis, in which calcium is deposited in the kidneys. Nephrocalcinosis is a dangerous condition that can lead to damage and kidney failure.
Effects on human health
The United States National Library of Medicine Toxicology Data Network lists several potential health side effects produced by magnesium stearate in humans. This network considers the chemical as slightly toxic if ingested. There have even been reports of deaths after accidental inhalation of baby talcum containing magnesium stearate as an ingredient. Accidental ingestion of a large dose can lead to acute magnesium toxicity manifested by weakness, decreased blood pressure and reduced heartbeat.
Other adverse effects
The International Program on Chemical Safety mentions several risks related to magnesium stearate. In addition to being spontaneously combustible, magnesium stearate emits toxic fumes and pungent smoke when heated. The International Program on Chemical Safety lists that this can affect breathing and cause the development of cough. Vomiting may also be caused as a result of ingestion of magnesium particles dispersed in the air as a result of heating.