What are the symptoms of low magnesium?

January 2021

What Magnesium Does

The human body needs many types of minerals to function properly, including magnesium. Various enzymes, which are specific types of proteins, facilitate more than 300 important biological processes in the body. These include, for example, producing RNA and DNA molecules, regulating nutrient levels, helping to prevent health conditions like depression and diabetes, and synthesizing new proteins [1, 2, 3].

What Causes Magnesium Deficiency?

Many people don’t consume sufficient quantities of magnesium in their diet. Although severe deficiencies of this vital nutrient are rare in industrialized nations, it is difficult to consume the recommended daily allowance (RDA) through food alone. Several factors are to blame, including industrial farming practices that deplete the soil (and thus anything grown in it) of magnesium, and food processing techniques that eliminate much of the remainder. The bottom line is that most Americans only get about half of the magnesium they need to function optimally.

Certain health conditions can worsen a magnesium deficiency, including diabetes, hypertension, pancreatitis, kidney disease, osteoporosis, migraines, and gastrointestinal illness. The reverse is also true; if you are already deficient in magnesium, that can exacerbate these conditions [3, 4]. People who have trouble absorbing nutrients, including the elderly and those with certain autoimmune diseases, are at a particularly high risk of magnesium deficiency [1]. Others at an elevated risk include women who have heavy menstrual periods; people taking diuretics, which can cause magnesium to be lost through the urine; people who sweat heavily due to strenuous physical activity, who don’t sleep well, or who are under heavy stress; and those taking certain types of steroids, antibiotics, and chemotherapy medications. Finally, drinking coffee, tea, or alcohol can make magnesium deficiency worse, as can eating too much sugar and salt [2, 3].

Magnesium Deficiency Symptoms

If you have a magnesium deficiency, it probably won’t show up on a standard blood test unless it is severe. That’s because almost all of the magnesium in the body is stored in the bones and soft tissues rather than in the blood. Moreover, the body tries to keep the level of magnesium in the blood constant, even if that means other parts of the body aren’t getting enough.  

Another reason that detecting a magnesium deficiency is challenging is that symptoms can be vague and easy to attribute to other causes [4]. Early signs of a magnesium deficiency include nausea, vomiting, muscle weakness, fatigue, and loss of appetite. As a magnesium deficiency gets worse, physical symptoms can include numbness, tingling, muscle contractions, seizures, abnormal heart rhythms, and coronary spasms. Muscle contractions and seizures are probably the result of an abnormally high level of calcium flowing into nerve cells, which stimulates them excessively. Those with very low magnesium levels might suffer from hypocalcemia (low serum calcium) or hypokalemia (low serum potassium) because a severe magnesium deficiency can disrupt the body’s ability to regulate mineral levels [2, 4, 5]. Finally, some animal studies have shown a link between magnesium deficiency and high blood pressure [10, 11], and at least one observational study has suggested the same link in humans [12].

In addition to physical symptoms, magnesium deficiencies can also cause mental issues or disorders. These can involve apathy, delirium, depression, or even a coma [6, 7]. Although some scientists believe that a magnesium deficiency might cause anxiety, and thus magnesium supplements might help some people with anxiety disorders, more studies are needed to confirm whether this is true [8, 9].

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1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride.” Washington, DC: The National Academies Press, 1997, 190-240. Available at:
2. Jahnen-Dechent, W., Ketteler, M. “Magnesium Basics.” Clinical Kidney Journal 5, 3-14 (2012).
3. Riley, P. Thomas. “Magnesium.” University of Mary Washington Student Health Center. July 2011.
4. Magnesium: Fact Sheet for Health Professionals.” National Institutes of Health, Office of Dietary Supplements. February 2016.