Magnesium is a naturally occurring mineral that your body needs for more than 300 biochemical reactions, according to the Office of Dietary Supplements. Health supplements containing magnesium may be taken for several reasons, including preventing magnesium deficiency in at-risk individuals. Although magnesium is generally safe, in large doses it may cause side effects, including diarrhea. As with any health supplement, you should ask your doctor before taking magnesium.
Diarrhea
Magnesium has well-documented laxative effects, and magnesium salts are often used to treat constipation. However, if too much magnesium is taken at one time, the laxative effect can work too well, resulting in diarrhea. In cases of severe diarrhea, abdominal pain and cramping may also develop. Other gastrointestinal symptoms, including nausea and upset stomach, can also occur, reports the University of Maryland Medical Center.
Maximum Dose
The Institute of Medicine has set a tolerable upper intake level, abbreviated UL, to indicate the maximum daily dose of magnesium. For adolescents and adults over the age of nine, the UL for magnesium is 350 mg per day. Generally speaking, if you do not take more than 350 mg of magnesium each day, you are unlikely to experience diarrhea and other side effects, explains the Linus Pauling Institute at Oregon State University.
Causes of Overdose
Magnesium is found in small amounts a wide variety of foods. Symptoms of magnesium toxicity rarely result from regular dietary consumption of magnesium-containing foods. Most cases of magnesium toxicity are caused by doses of supplemental magnesium that are too large. If you think you need supplemental magnesium, consult with your doctor to determine the best dose for you.
Other Side Effects
In addition to diarrhea and other gastrointestinal side effects, large doses of magnesium can cause a variety of other side effects. Some side effects can be severe, including muscle weakness, dangerously low blood pressure, difficulty breathing and heart arrhythmias. Changes in mood and mental status may also occur, including confusion, lowered awareness, coma and possibly death, warns the University of Maryland Medical Center.
