Diarrhea & Dizziness With Magnesium Overdose

Magnesium is available in many foods, such as nuts, beans and grains, and in multivitamins that contain minerals. People with low levels of magnesium or with certain health conditions benefit from magnesium supplements. Commercial magnesium preparations also are available for use as antacids and as laxatives. Consuming enough magnesium to cause an overdose can be dangerous. Consult a qualified health care provider before taking supplemental magnesium.

Magnesium Benefits

Magnesium is essential for bone growth and maintenance and for nerve and muscle function. Getting enough magnesium in the diet is helpful for people with conditions such as high cholesterol, osteoporosis, angina and premenstrual syndrome. However, consuming large amounts of magnesium in supplements, laxatives or antacids may lead to serious side effects.

Side Effects

Magnesium supplements usually don't cause side effects, but you don't need to overdose on magnesium to develop diarrhea. That's one of the more common side effects of magnesium, along with upset stomach. Some people also experience nausea and vomiting when they take extra magnesium.

Magnesium Overdose

An overdose of magnesium can cause the more common side effects of diarrhea, upset stomach and nausea, along with other effects that call for immediate medical attention. If you take magnesium supplements and develop dizziness, extreme drowsiness, fainting, flushing, difficulty breathing, confusion, or blurred or double vision, call your doctor immediately. These symptoms may be signs of a serious electrolyte imbalance, abnormally low blood pressure or a slow or irregular heart rate. They can lead to muscle paralysis or s coma and can even be fatal.


If you're pregnant and taking calcium channel blocker blood pressure medicine, magnesium supplementation may increase the risk of side effects such as dizziness, fluid retention and nausea. Taking magnesium while also taking antibiotics or bisphosphates can reduce the absorption of the medications, making them less effective. Kidney dysfunction can cause a buildup of magnesium in the body if you take magnesium supplements or digestive aids containing magnesium. This may lead to overdose side effects. Some diuretics also have this effect. Consult your doctor before using magnesium supplements, antacids or laxatives if any of these situations describes you.


The tolerable upper intake level, for magnesium supplements is 350 milligrams per day for people ages 9 years and over, according to the Office of Dietary Supplements. The office reports that doctors may recommend higher doses for treating specific medical problems. The highest medicinal dose is 1,830 milligrams per day for migraine headaches, in the form of magnesium citrate in three divided doses for up to three months. Talk with your doctor before taking doses of magnesium higher than the upper intake level.