Magnesium Side Effects

A healthy, balanced diet that includes fiber-rich foods like fruits, vegetables, and grains is a good source of vitamins and minerals such as magnesium. Dietary magnesium promotes health and does not pose a health risk. However, pharmacologic doses of magnesium such as those found in supplements can have adverse effects especially when taken in large amounts or when a health problem affects its use.

Upper Limits of Magnesium Intake

There is no upper limit for magnesium that comes from dietary sources; however, according to the Institute of Medicine, for magnesium supplements, one must take care to observe these tolerable upper limits for intake:

• For children 1-3 years old – 65 mg/day

• For children 4-8 years old – 110 mg/day

• Older than 8 years to adulthood – 350 mg/day

Magnesium is therefore considered to be likely safe for most people when used correctly, in doses less than 350 mg/day for healthy adults.

Risks and Side Effects of magnesium

Magnesium supplements may possibly be unsafe when taken in large doses or when used by people who have certain health problems.

Minor side effects of taking these supplements are common, and these include diarrhea and abdominal cramping, stomach upset, nausea, and vomiting.

Taking large doses of these supplements on a regular basis might cause a build-up of magnesium in the body, causing serious side effects like confusion, irregular heartbeats, low blood pressure, slowed breathing, coma, and death.

Special precautions and warnings are given to people who have kidney disease and kidney failure, since these conditions may cause failure to eliminate excess magnesium from the body even when these supplements are taken in regular doses. Although dietary magnesium may not harm them, taking extra magnesium can cause a build-up of these minerals to dangerous levels.

Another condition that requires precaution is for people who have heart blocks, a type of heart rhythm irregularity, since magnesium influences electrical conduction and contraction of the heart. People with other types of heart rate irregularities such as atrial fibrillation and bradycardia (excessively slow heart rate) should consult a doctor before taking magnesium supplements.

Aside from taking magnesium as a dietary supplement, people also take magnesium in the form of antacids to relieve indigestion or laxatives to relieve constipation. However, taking too much of these antacids and laxatives may also lead to magnesium toxicity.

Signs of magnesium toxicity may be similar to those of magnesium deficiency. These include irregular heartbeat, changes in mental status, loss of appetite, nausea, diarrhea, muscle weakness, extremely low blood pressure, and difficulty in breathing.