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Magnesium is an element (Mg) with an atomic weight of 24.312 and the atomic number 12. In its elemental form, magnesium is a light, silver-white metal. It is a cation, which means that its ion has a positive charge. Of the cations in the human body, magnesium is the fourth-most abundant. Ninety-nine percent of the body's magnesium is contained within its cells: about 60% in the bones, 20% in the muscles, 19%20% in the soft tissue, and 1% circulates in the blood. Important to both nutrition and medicine, magnesium, like calcium and phosphorus , is considered a major mineral. Magnesium in its carbonate and sulfate forms has been used for centuries as a laxative. The name of the element comes from Magnesia, a city in Greece where large deposits of magnesium carbonate were discovered in ancient times.

Magnesium is an important element in the body because it activates or is involved in many basic processes or functions, including:

  • cofactor for over 300 enzymes
  • oxidation of fatty acids
  • activation of amino acids
  • synthesis and breakdown of DNA
  • neurotransmission
  • immune function
  • interactions with other nutrients, including potassium , vitamin B6, and boron

General use

Magnesium has a number of general uses, primarily in standard allopathic medicine, but also in some alternative therapies.


The Food and Nutrition Board of the National Academy of Sciences has established the following dietary reference intakes (DRIs) and tolerable upper limits (ULs) for magnesium: Infants and children 06 months, 30 mg; 712 months, 75 mg; 13 years, 80 mg; 48 years, 130 mg; 913 years 240 mg. Males 1418 years, 410 mg; 1930 years, 400 mg; over 30 years, 420 mg. Females 1418 years, 360 mg; 1930 years, 310 mg; over 30 years, 320 mg. The ULs apply only to magnesium taken as a dietary supplement or given for medical reasons, since no toxicity from magnesium occurring naturally in foods has been reported. The ULs for magnesium are: 13 years, 65 mg; 48 years, 110 mg; 9 years and over, 350 mg.

Good dietary sources of magnesium include nuts; dried peas and beans; whole grain cereals such as oatmeal, millet, and brown rice; dark green vegetables; bone meal; blackstrap molasses; brewer's yeast ; and soy products. Dark green vegetables are important sources of magnesium because it is the central atom in the structure of chlorophyll. Drinking hard water or mineral water can also add magnesium to the diet.

A severe magnesium deficiency in a healthy person is unusual because normal kidneys are very efficient in keeping magnesium levels balanced. This condition, called hypomagnesemia, is usually caused either by disease (kidney disease, severe malabsorption, chronic diarrhea, hyperparathyroidism , or chronic alcoholism ) or as a side effect of certain medications, most commonly diuretics, cisplatin (a cancer medication), and a few antibiotics. The symptoms of hypomagnesemia include disturbances of the heart rhythm, muscle tremors or twitches, seizures, hyperactive reflexes, and occasional personality changes (depression or agitation). A patient with hypomagnesemia may also produce Chvostek's sign, which is a facial spasm caused when the doctor taps gently over the facial nerve. This condition of painful intermittent muscle contractions and spasms is known as tetany. Hypomagnesemia can be treated with either oral or intravenous preparations containing magnesium.

Magnesium toxicity (hypermagnesemia) is rare because excessive amounts are usually excreted in the urine and feces. Most cases of hypermagnesemia are caused by overuse of dietary supplements containing magnesium. The symptoms of magnesium toxicity include central nervous system depression, muscle weakness, fatigue , and sleepiness. In extreme cases, hypermagnesemia can cause death. It can be treated with intra-venous calcium gluconate along with respiratory support. Severe hypermagnesemia can be treated by hemodialysis or peritoneal dialysis.

Standard medical practice

DIAGNOSIS. The levels of magnesium in a patient's blood or body fluids can help diagnose several illnesses. A high magnesium level in the blood may indicate kidney failure, hypothyroidism , severe dehydration, Addison's disease, or overingestion of antacids containing magnesium. A low blood level of magnesium may indicate hypomagnesemia. Because 99% of the body's magnesium is contained in its cells, blood tests can only measure the approximately 1% of magnesium that is extra-cellular (circulating in the bloodstream). This makes it difficult to diagnose low magenesium levels.

Fortunately, magnesium levels in urine can also aid diagnosis. High levels of urinary magnesium may indicate overconsumption of supplemental magnesium, overuse of diuretics, hypercalcemia (too much calcium in the body), hypophosphatemia (too little phosphate in the body), or metabolic acidosis (high blood acid levels). Low levels of magnesium in the urine may point to hypomagnesemia or hypocalcemia (too little magnesium or calcium in the body), an underactive parathyroid gland, or metabolic alkalosis (high blood alkaline levels).

TREATMENT. Magnesium is used to treat tachycardia (excessively rapid heartbeat) and low levels of electrolytes (chloride, potassium, and sodium ). It helps manage premature labor, and can be given prophylactically to prevent seizures in toxemia of pregnancy . In 2002, a major international study verified the effectiveness of magnesium sulfate in preventing eclampsia, a potentially fatal seizure condition in pregnant women. Not only is it effective, but at a cost of about $5 per patient, it proves less expensive as well.

Magnesium helps control seizures resulting from hypomagnesemia associated with alcoholism, Crohn's disease , or hyperthyroidism . Magnesium injections are also used to treat acute asthma attacks.

Magnesium preparations may be given as antacids in the treatment of peptic ulcers and hyperacidity. They are also given as laxatives for the short-term relief of constipation or to empty the patient's bowel prior to surgery or certain diagnostic procedures. Magnesium hydroxide is used to treat patients who have been poisoned by mineral acids or arsenic.

Magnesium in the form of magnesium sulfate is known as Epsom salts. It can be taken by mouth as a laxative, but is also used externally to reduce tissue swelling, inflammation, and itching from insect bites, heat rash, or other minor skin irritations. Epsom salts can be applied to the affected skin or body part in moist compresses, or dissolved in warm bath water.

Recent research indicates that magnesium deficiency may contribute to atherosclerosis (hardening of the arteries), as well as to necrotizing enterocolitis (NEC), a sometimes-deadly inflammation that destroys the bowel in premature infants. Magnesium may also be useful in treating attention-deficit hyperactivity disorder (ADHD) and migraine headaches.

Alternative medicine

HOMEOPATHY. Phosphate of magnesia is a staple homeopathic remedy, called Magnesia phosphorica (Mag. phos.) It is recommended for symptoms that are relieved by the application of warmth and gentle pressure, such as hiccups accompanied by colic in infants, menstrual cramps that are relieved when the woman bends forward, and abdominal pain without nausea and vomiting . Patients who benefit from Mag. phos. are supposedly less irritable or angry in temperament than those who need Colocynthis or Chamomilla.

NATUROPATHY. Naturopaths emphasize the importance of proper food selection and preparation to obtain an adequate supply of nutrients in the diet. They maintain that modern methods of agriculture promote overcropping and soil depletion, which they believe reduces the amount of magnesium (and other minerals) available from food grown in that soil. The processing and refining of wheat and rice, which discards the magnesium contained in the bran, wheat germ , or rice husks, also reduces the amount of magnesium in these foods. For these reasons naturopaths often recommend organic produce, which they believe contains higher levels of minerals, and suggest that they not be overcooked or boiled in too much water. In addition, this water, or "pot liquor," is often rich in magnesium that cooks out of the vegetables. It should not be discarded but saved for use in soups or stews.

Many naturopaths believe that the official government recommended daily allowance (RDA) of magnesium is too low. They think that it should be doubled to about 600 or 700 mg daily for adults. Most recommend the use of dietary supplements containing magnesium to make up the difference.

Naturopathic practitioners regard magnesium to be important in the relief or cure of the following conditions:

  • Mitral valve prolapse: Magnesium deficiency may lower the body's ability to repair defective connective tissue, including defective mitral valves.
  • Atherosclerosis.
  • Certain psychological conditions, including apathy, decreased ability to learn, memory loss , and confusion.
  • Kidney stones : Magnesium increases the solubility of certain calcium compounds that form kidney stones if they are not excreted in the urine.
  • Hypertension: Hypertensive people often have lower levels of magnesium within their cells than people with normal blood pressure.
  • Angina pectoris: Magnesium is thought to relax spastic arteries and help prevent arrhythmias.
  • Osteoporosis : Many osteoporosis patients have low levels of magnesium in their bodies.
  • Premenstrual syndrome (PMS) and menstrual cramps: Some women report relief from the symptoms of PMS when taking magnesium supplements.
  • Naturopaths also treat asthma, epilepsy, autism , hyperactivity, chronic fatigue syndrome , noise-induced hearing loss, insomnia , and stress-related anxiety with supplemental magnesium.


Dietary supplements

Naturopaths generally recommend supplemental magnesium for people with high blood cholesterol , post-menopausal women, women taking birth control pills, diabetics, people who eat a lot of fast food or other highly processed food, and people who drink alcohol. Many nutrition experts recommend supplements that contain a balanced ratio of calcium to magnesium, usually two parts of calcium to one of magnesium. People who increase their calcium intake should increase their dose of magnesium (and phosphate) as well, because they work together and complement each other.

Some naturopaths recommend taking magnesium in the form of an aspartate or a citrate, arguing that these compounds are more easily absorbed by the body than magnesium carbonate or magnesium oxide. Others prefer magnesium chelated (combined with a metallic ion) with amino acids. Magnesium can also be obtained from herbal sources, such as red raspberries.

Standard medical preparations

Magnesium hydroxide is a common over-the-counter antacid, available as either a tablet or liquid. Most antacid tablets contain about 200 mg of magnesium hydroxide; liquid magnesium hydroxide is sometimes called milk of magnesia. Magnesium carbonate works as a cathartic or laxative when combined with citric acid to produce magnesium citrate; it is often flavored with lemon or cherry to make it more pleasant to swallow. Magnesium sulfate (in the form of Epsom salts) is available over the counter, usually in half-pound or pound boxes. Epsom salts are small whitish or colorless crystals that dissolve easily in water and have a bitter or salty taste.

Magnesium for intravenous dosage is prepared as a sulfate in a 50% solution. In general, intravenous administration of magnesium is reserved for patients with such serious symptoms as seizures, preeclampsia or eclampsia of pregnancy, acute asthma attacks, or severe cardiac arrhythmias. Magnesium sulfate can also be given by intramuscular injection.


Preparations containing magnesium should not be given as laxatives to patients with kidney disease, nausea and vomiting, diarrhea, abdominal pain, rectal bleeding, symptoms of appendicitis , or symptoms of intestinal obstruction or perforation. In addition, these preparations should not be used routinely to relieve constipation, as the patient may become dehydrated, lose calcium from the body, or develop a dependence on them. Antacids containing magnesium should be used with caution in patients with kidney disease.

Side effects

Magnesium preparations taken internally may cause hypermagnesemia, especially with prolonged use; electrolyte imbalance; and abdominal cramps when taken as a laxative. Milk of magnesia occasionally produces nausea or diarrhea. There are no known side effects of Epsom salts when used externally.


Milk of magnesia will decrease the patient's absorption of chlordiazepoxide, digoxin, isoniazid, quinolones, or tetracycline antibiotics. Because it increases the gastrointestinal tract's mobility, magnesium can also decrease the absorption (and thereby the effectiveness) of many other drugs and supplements as well. Magnesium sulfate, if given intravenously, is incompatible with calcium gluceptate, clindamycin, dobutamine, polymyxin B sulfate, procaine, and sodium bicarbonate.



Baron, Robert B., MD, MS. "Nutrition." In Current Medical Diagnosis & Treatment 2000. Edited by Lawrence M. Tierney, Jr., MD, et al. New York: Lange Medical Books/McGraw-Hill, 2000.

Beers, Mark H., MD, and Robert Berkow, MD, eds. The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 1999.

Burton Goldberg Group. Alternative Medicine: The Definitive Guide. Fife, WA: Future Medicine Publishing, Inc., 1995.

Murray, Michael, ND, and Joseph Pizzorno, ND. Encyclopedia of Natural Medicine. Rocklin, CA: Prima Publishing, 1991.

Okuda, Toshihiro, MD, PhD, Kiyoshi Kurokawa, MD, MACP, and Maxine A. Papadakis, MD. "Fluid & Electrolyte Disorders." In Current Medical Diagnosis and Treatment 2000, edited by Lawrence M. Tierney, Jr., MD et al. New York: Lange Medical Books/McGraw-Hill, 2000.

Russell, Percy J., and Anita Williams. The Nutrition and Health Dictionary. New York: Chapman & Hall, 1995.


"Help for Eclampsia." American Medical News (June 17, 2002): 32.


American Association of Naturopathic Physicians. P. O. Box 20386. Seattle, WA 98112.

Committee on the Scientific Evaluation of Dietary Reference Intakes. Institute of Medicine (1997) Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, DC: National Academy Press, 1997.

Homeopathic Pharmacopoeia of the United States. P. O. Box 2221. Southeastern, PA 19399-2221. (610) 783-5124. Fax: (610) 783-5180. Publishes and distributes the Homeopathic Pharmacopoeia of the U.S., which defines the contents of homeopathic remedies and other preparations.

Rebecca J. Frey, PhD

Teresa G. Odle

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Magnesium (revised)


Note: This article, originally published in 1998, was updated in 2006 for the eBook edition.


Magnesium is the second element in Group 2 (IIA) of the periodic table a chart that shows how chemical elements are related to each other. The elements in Group 2 are known as the alkaline earth elements. Other elements in that group include beryllium, calcium, strontium, barium, and radium.

Compounds of magnesium have been used by humans for centuries. Yet, the element itself was not isolated until 1808. The long delay occurred because magnesium forms very stable compounds. That means that such compounds do not break down very easily.

Magnesium is the seventh most abundant element in the Earth's crust. It also occurs in large amounts dissolved in ocean waters.




Group 2 (IIA)
Alkaline earth metal


Large amounts of magnesium are used to make alloys. An alloy is made by melting or mixing two or more metals. The mixture has properties different from those of the individual metals. Magnesium alloys are quite light, yet very strong. This property makes them useful in the construction of airplanes and space-craft.

About 70 percent of the magnesium compounds produced in the United States are used in the manufacture of refractory materials. A refractory material is one that can withstand very high temperatures by reflecting heat. Refractory materials are used to line the ovens that maintain high temperatures. The remaining 30 percent of magnesium compounds are used in agriculture, construction, industrial, and chemical operations.

Discovery and naming

Compounds of magnesium are very abundant in the Earth. Dolomite, or calcium magnesium carbonate (CaMg(CO32, is an example. Dolomite has been used as a building material for centuries.

Another well-known magnesium compound is Epsom salts, or magnesium sulfate (MgSO4. Epsom salts are known for their soothing qualities, most notably when added to a bath. (See accompanying sidebar.)

The allure of Epsom salts

P erhaps the best know magnesium compound is magnesium sulfate (MgSO4). It is popularly known as Epson salts.

One of the earliest stories about Epsom salts dates back to 1618. The town of Epsom, in Surrey, England, was suffering from a severe drought. A farmer named Henry Wicker brought his cattle to drink from a water hole on the town commons (central park). But the cattle would not drink the water. Wicker was surprised because he knew they were very thirsty. He tasted the water himself and found that it was very bitter.

The bitterness was due to magnesium sulfate in the water. This compound became known as Epsom salts.

People soon learned that soaking in the natural waters that contained Epsom salts made them feel better. The salts seemed to have properties that soothed the body. Before long, soaking in these waters became very popular.

Today, Epsom salts are used in bath water. They relax sore muscles and remove rough skin. Many people believe the salts have the same relaxing effect as hot springs. Some gardeners even believe that sprinkling Epsom salts in the garden helps flowers and vegetables grow!

Careful studies of magnesium and its compounds began in the middle 1700s. Scottish physician and chemist Joseph Black (1728-99) carried out some of the earliest experiments on magnesium compounds. He reported on his research in an article that became famous. Black is sometimes given credit for "discovering" magnesium because of his work with the element.

By 1800, chemists knew that magnesium was an element. But no one had been able to prepare pure magnesium metal. Magnesium holds very tightly to other elements in its compounds. No one had found a way to break the bonds between magnesium and these other elements.

In 1808, English chemist Humphry Davy (1778-1829) solved the problem by passing an electric current through molten (melted) magnesium oxide (MgO). The current caused the compound to break apart, forming magnesium metal and oxygen gas:

Davy used this method to discover a number of other elements. (See sidebar on Davy in the calcium entry in Volume 1.) Like magnesium, these elements form compounds that are very difficult to break apart. An electric current provides the energy to break these compounds down into their elements.

The name magnesium goes back many centuries. It was selected in honor of a region in Greece known as Magnesia. The region contains large supplies of magnesium compounds.

Physical properties

Magnesium is a moderately hard, silvery-white metal. It is the lightest of all structural metals. These metals are strong enough to be used to build buildings, bridges, automobiles, and airplanes.

Magnesium is easily fabricated. Fabrication means shaping, molding, bending, cutting, and working with a metal. Metals must be fabricated before they can be turned into useful products. Metals that are strong, tough, or hard are not easily fabricated. They must be converted to an alloy. A metal that is more easily fabricated (such as magnesium) is combined with them.

The melting point of magnesium is 651°C (1,200°F) and its boiling point is 1,100°C (2,000°F). Its density is 1.738 grams per cubic centimeter.

Chemical properties

Magnesium is a fairly active metal. It reacts slowly with cold water and more rapidly with hot water. It combines with oxygen at room temperature to form a thin skin of magnesium oxide. It burns with a blinding white light at higher temperatures. Magnesium reacts with most acids and with some alkalis. An alkali is a chemical with properties opposite those of an acid. Sodium hydroxide (common lye such as Drano) and lime-water are examples of alkalis.

Magnesium also combines easily with many non-metals, including nitrogen, sulfur, phosphorus, chlorine, fluorine, bromine, and iodine. It also reacts readily with a number of compounds, such as carbon monoxide (CO), carbon dioxide (CO2, sulfur dioxide (SO2, and nitric oxide (NO).

Occurrence in nature

The abundance of magnesium in the Earth's crust is estimated to be about 2.1 percent. That makes it the sixth most common element in the earth. It also occurs in seawater. A cubic mile of seawater is estimated to contain up to six million tons of magnesium.

There are many naturally occurring minerals of magnesium. Some of the most important are dolomite; magnesite, or magnesium carbonate (MgCO3; carnallite, or potassium magnesium chloride (KMgCl3; and epsomite, or magnesium sulfate (MgSO4.

The largest producer of magnesium ores is Turkey. Other large producers are North Korea, China, Slovakia, Austria, and Russia. The amount of magnesium produced in the United States is not reported in order to protect trade secrets.

Magnesium produced in the United States comes from three sources: seawater, brine, and mines. Seawater is processed to obtain magnesium by companies in California, Delaware, Florida, and Texas. Magnesium is obtained from brine in Michigan and Utah. Brine is water that is even saltier than seawater. Finally, some magnesium compounds are taken from mines in Nevada, North Carolina, and Washington.


There are three naturally occurring isotopes of magnesium: magnesium-24, magnesium-25, and magnesium-26. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope.

One radioactive isotope of magnesium, magnesium-28, also exists. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. Magnesium-28 has no important commercial uses.


Magnesium is prepared by one of two methods. The first method is similar to the method used by Davy in 1808. An electric current is passed through molten (melted) magnesium chloride:

The second method involves reacting magnesium oxide with ferrosilicon. Ferrosilicon is an alloy of iron and silicon. When magnesium oxide and ferrosilicon react, free magnesium metal is formed.


Although most cameras now use electronic flashes, magnesium metal is often contained in cameras that use flash bulbs. A thin strip of magnesium metal is inside the bulb. When the flash is ignited, the magnesium strip catches fire. It burns with a very bright white light. The light from the bulb illuminates a scene for the photograph.

A common use of magnesium metal is in fireworks. Most firework displays include some brilliant flashes of very white light. Those flashes are produced by the burning of magnesium metal.

Magnesium is commonly alloyed with other metals. Magnesium and aluminum, for instance, are two metals that combine to form alloys that are very strong and resistant to corrosion (rust). But they weigh much less than steel alloys with similar properties.

Strength and low density are important properties in the manufacture of airplanes, automobiles, metal luggage, ladders, shovels and other gardening equipment, racing bikes, skis, race cars, cameras, and power tools. A typical magnesium alloy contains about 90 percent magnesium, 2 to 9 percent aluminum, and small amounts of zinc and manganese.


The largest single use of magnesium compounds is in refractories. Other magnesium compounds are used in the following categories:

medicine: pain killer and fever reducer (magnesium acetylsalicylate); antacid to neutralize stomach acid (magnesium hydroxide; magnesium phosphate; magnesium silicate); laxative to loosen the bowels (magnesium carbonate; magnesium chloride; magnesium citrate; magnesium hydroxide; magnesium lactate; magnesium phosphate); antiseptic to kill germs (magnesium borate; magnesium salicylate; magnesium sulfate); sedative to help one get sleep (magnesium bromide)

production of glass and ceramics: magnesium fluoride; magnesium oxide

mothproofing of textiles: magnesium hexafluorosilicate

fireproofing wood for construction: magnesium phosphate

manufacture of paper: magnesium sulfite

Health effects

Magnesium is essential for good health in both plants and animals. It forms part of the chlorophyll molecule found in all green plants. Chlorophyll is the molecule in green plants that controls the conversion of carbon dioxide and water to carbohydrates, such as starch and sugar. Plants that do not get enough magnesium cannot make enough chlorophyll. Their leaves develop yellowish blotches as a result.

Magnesium is found in many enzymes in both plants and animals. An enzyme is a catalyst in a living organism. It speeds up the rate at which certain changes take place in the body. Enzymes are essential in order for living cells to function properly. It is difficult not to get enough magnesium in one's daily diet. It is found in nuts, cereals, seafoods, and green vegetables. Most people have no problem getting the 300 to 400 milligrams of magnesium recommended in the daily diet.

Magnesium forms part of the chlorophyll molecule found in all green plants.

A lack of magnesium can occur, however. For example, alcoholics and children in poor countries sometimes develop a magnesium deficiency. In such cases, magnesium deficiency may cause a person to become easily upset or overly aggressive.

On the other hand, it is also possible to be exposed to too much magnesium. For example, inhaling magnesium powder can produce irritation of the throat and eyes, resulting in a fever. In large doses, magnesium can cause damage to muscles and nerves. It can eventually result in loss of feeling and paralysis (inability to move parts of the body).

Such conditions are rare. They are likely to occur only among people who have to work with magnesium metal on a regular basis.

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Magnesium Imbalance

Magnesium Imbalance


A mineral found in the fluid that surrounds cells, magnesium (Mg) is an essential component of more than 300 enzymes that regulate many body functions. Imbalances occur when the blood contains more or less magnesium than it should.


Magnesium is necessary for the formation and functioning of healthy bones, teeth, muscles, and nerves. It converts food into energy, builds proteins, and is instrumental in maintaining adequate levels of calcium in the blood. Magnesium helps prevent cardiovascular disease and irregular heartbeat, reduces the risk of bone loss (osteoporosis ), and increases an individual's chance of surviving a heart attack. It may also help prevent stroke and lessen the effects of existing osteoporosis.

Fish, dairy products, leafy green vegetables, legumes, nuts, seeds, and grains are especially good sources of magnesium, but varying amounts of this mineral are found in all foods. Some is stored in the kidneys, and excess amounts are excreted in the urine or stools.

Magnesium deficiency (hypomagnesemia) or excess (hypermagnesemia) is rare, but either condition can be serious.

Causes and symptoms


Magnesium deficiency most often occurs in people who have been fed intravenously for a long time, whose diet does not contain enough magnesium, or who are unable to absorb and excrete the mineral properly.

Secreting too much aldosterone (the hormone that regulates the body's salt-fluid balance), ADH (a hormone that inhibits urine production), or thyroid hormone can cause hypomagnesemia.

Other factors associated with hypomagnesemia include:

  • Loss of body fluids as a result of stomach suctioning or chronic diarrhea
  • Cisplatin (a chemotherapy drug)
  • Long-term diuretic therapy
  • Hypercalcemia (abnormally high levels of calcium in the blood)
  • Diabetic acidosis (a condition in which the body's tissues have a higher-than-normal acid content)
  • Complications of bowel surgery
  • Chronic alcoholism
  • Malnutrition
  • Starvation
  • Severe dehydration.

People who have hypomagnesemia usually experience loss of weight and appetite, bloating, and muscle pain, and they pass stools that have a high fat content. Also, they may be listless, disoriented, confused, and very irritable. Other symptoms of hypomagnesemia are:

  • Nausea
  • Vomiting
  • Muscle weakness
  • Tremor
  • Irregular heart beat
  • Delusions and hallucinations
  • Leg and foot cramps
  • Muscle twitches
  • Changes in blood pressure.

Severe magnesium deficiency can cause seizures, especially in children.

Neonatal hypomagnesemia can occur in premature babies and in infants who have genetic parathyroid disorders or who have had blood transfusions. This condition also occurs in babies born to magnesium-deficient mothers or to women who have:

  • Diabetes mellitus
  • Hyperparathyroidism (overactive parathyroid glands)
  • Toxemia (a pregnancy-related condition characterized by high blood pressure and fluid retention).


Hypermagnesemia is most common in patients whose kidneys cannot excrete the magnesium they derive from food or take as medication. This condition can also develop in patients who take magnesium salts, or in healthy people who use large quantities of magnesium-containing antacids, laxatives, or analgesics (pain relievers).

Magnesium poisoning can cause severe diarrhea in young people, and mask the symptoms of other illnesses. Very high overdoses can lead to coma. The risk of complications of magnesium poisoning is greatest for:

  • Elderly people with inefficient kidney function
  • Patients with kidney problems or intestinal disorders
  • People who use antihistamines, muscle relaxants, or narcotics.

Severe dehydration or an overdose of supplements taken to counteract hypomagnesemia can also cause this condition.

People who have hypermagnesemia may feel flushed and drowsy, perspire heavily, and have diarrhea. Breathing becomes shallow, reflexes diminish, and the patient becomes unresponsive. Muscle weakness and hallucinations are common. The patient's heart beat slows dramatically and blood pressure plummets. Extreme toxicity, which can lead to coma and cardiac arrest, can be fatal.


Blood tests are used to measure magnesium levels.


The goal of treatment is to identify and correct the cause of the imbalance. Oral magnesium supplements or injections are usually prescribed to correct mild magnesium deficiency. If the deficiency is more severe or does not respond to treatment, magnesium sulfate or magnesium chloride may be administered intravenously.

Doctors usually prescribe diuretics (urine-producing drugs) for patients with hypermagnesemia and advise them to drink more fluids to flush the excess mineral from the body. Patients whose magnesium levels are extremely high may need mechanical support to breathe and to circulate blood throughout their bodies.

Intravenously administered calcium gluconate may reverse damage caused by excess magnesium. Intravenous furosemide (Lasix) or ethacrynic acid (Edecrin) can increase magnesium excretion in patients who get enough fluids and whose kidneys are functioning properly.

In an emergency, dialysis can provide temporary relief for patients whose kidney function is poor or who are unable to excrete excess minerals.


Because imbalances may recur if the underlying condition is not eliminated, monitoring of magnesium levels should continue after treatment has been completed.


Most people consume adequate amounts of magnesium in the food they eat. Dietary supplements can be used safely, but should only be used under a doctor's supervision.


Hypermagnesemia An abnormally high concentration of magnesium in the blood.

Hypomagnesemia An abnormally low concentration of magnesium in the blood.



"Mineral Guide." CNN Page. May 2, 1998.

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magnesium (măgnē´zēəm, –zhəm), metallic chemical element; symbol Mg; at. no. 12; at. wt. 24.3050; m.p. about 648.8°C; b.p. about 1,090°C; sp. gr. 1.738 at 20°C; valence +2. In 1808, Sir Humphry Davy discovered magnesium in its oxide, although it is not certain that he isolated the metal. Pure magnesium was isolated substantially by A. A. B. Bussy in 1828 by chemical reduction of the chloride. Magnesium was first isolated electrolytically by Michael Faraday in 1833.


Magnesium is a ductile, silver-white, chemically active metal with a hexagonal close-packed crystalline structure. It is malleable when heated. Magnesium is one of the alkaline-earth metals in Group 2 of the periodic table. It reacts very slowly with cold water. It is not affected by dry air but tarnishes in moist air, forming a thin protective coating of basic magnesium carbonate, MgCO3·Mg(OH)2. When heated, magnesium powder or ribbon ignites and burns with an intense white light and releases large amounts of heat, forming the oxide, magnesia, MgO. A magnesium fire cannot be extinguished by water, since water reacts with hot magnesium and releases hydrogen. Magnesium reacts with the halogens and with almost all acids. It is a powerful reducing agent and is used to free other metals from their anhydrous halides.


Magnesium forms many compounds. The oxide, hydroxide, chloride, carbonate, and sulfate are commercially important. They are used in ceramics, cosmetics, fertilizers, insulation, leather tanning, and textile processing. Epsom salts (magnesium sulfate heptahydrate, MgSO4·7H2O), milk of magnesia (magnesium hydroxide, Mg(OH)2), and citrate of magnesia are used in medicine. Magnesium reacts with organic halides to form the Grignard reagents of organic chemistry.

Natural Occurrence

Magnesium is the eighth most abundant element in the earth's crust but does not occur uncombined in nature. It is found in abundance in the minerals brucite, magnesite, dolomite, and carnalite. It is also found (as the silicate) in asbestos, meerschaum, serpentine, and talc. Magnesium chloride is found in seawater, brines, and salt wells. Mineral waters often contain salts of magnesium; the magnesium ion imparts a bitter flavor. Magnesium is a constituent of the chlorophyll in green plants and is necessary in the diet of animals and humans.

Commercial Preparation

Two methods of producing magnesium commercially are used. The principal method is the electrolysis of fused magnesium chloride, which is used in the extraction of magnesium from seawater (the principal source) and from dolomite. In recovery from seawater, the magnesium is precipitated as magnesium hydroxide by treatment with lime (calcium oxide) obtained from oyster shells. The hydroxide is collected and treated with hydrochloric acid to form the chloride. The chloride is fused and electrolyzed, forming magnesium metal and chlorine gas. The molten metal is cast into ingots for further processing; the chlorine gas is made into hydrochloric acid and is reused to form magnesium chloride. About 1 lb of magnesium is recovered from each 100 gal of seawater; the oceans are a virtually inexhaustible source of this metal. A second method of magnesium production, called the ferrosilicon process, involves the reduction of magnesium oxide (prepared by calcining dolomite) with an iron-silicon alloy.


Magnesium is a commercially important metal with many uses. It is only two thirds as dense as aluminum. It is easily machined, cast, forged, and welded. It is used extensively in alloys, chiefly with aluminum and zinc, and with manganese. Magnesium alloys were used as early as 1910 in Germany. Early structural uses of magnesium alloys were in aircraft fuselages, engine parts, and wheels. They are now also used in jet-engine parts, rockets and missiles, luggage frames, portable power tools, and cameras and optical instruments. Duralumin and magnalium are alloys of magnesium. The metal is also used in pyrotechnics, especially in incendiary bombs, signals, and flares, and as a fuse for thermite. It is used in photographic flashbulbs and is added to some rocket and missile fuels. It is used in the preparation of malleable cast iron. An important use is in preventing the corrosion of iron and steel, as in pipelines and ship bottoms. For this purpose a magnesium plate is connected electrically to the iron. The rapid oxidation of the magnesium prevents the slower oxidation and corrosion of the iron.

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melting point: 651°C
boiling point: 1,107°C
density: 1.738 g/cm
3 at 20°C
most common ions: Mg

Magnesium was first recognized as an element by Joseph Black in 1755. In 1808 Sir Humphry Davy isolated the element, and in 1831 H. Bussy devised a method for producing it. Magnesium, in its combined states, is readily abundant and is the eighth most common element in Earth's crust. Magnesium metal is silvery white in color.

The most common method for producing elemental magnesium is in fused salt electrolytic cells, wherein magnesium chloride (MgCl2) is decomposed by applying a voltage to elemental magnesium and chlorine gas. The magnesium chloride feed is obtained directly from seawater or from magnesium oxide deposits containing magnesite or dolomite. In these cases, the oxide is first chlorinated prior to electrolysis. Another method is to produce magnesium directly from the oxide by reducing the oxide with silicon under vacuum. The resultant Mg vapor is condensed to recover Mg metal. This process is carried out in vacuum retorts and is known as the Pidgeon process.

The principal uses of Mg are for alloying with aluminum, for desulphurizing steel and pig iron, and for nodularizing the graphite in cast irons. Recently, researchers have focused on using Mg alloys to produce lightweight components in automobiles. As a result, Mg usage in vehicles is steadily increasing.

Compounds of magnesium, including the hydroxide, the chloride, the citrate, and the sulfate, are used in the medical field. Magnesium is an important element in both animal and plant life. On average, adults require a daily intake of about 300 milligrams (0.011 ounces) of magnesium.

see also Alkaline Earth Metals; Black, Joseph; Davy, Humphry; Inorganic Chemistry.

Frank Mucciardi


Kramer, Deborah A. (2001). "Magnesium, Its Alloys and Compounds." U.S. Geological Survey Open-File Report 01-341. Also available from <>.

Raloff, J. (1998). "Magnesium: Another Metal to Bone up On." Science News. 154(9):134.

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magnesium (mag-nee-ziŭm) n. a metallic element essential to life. Magnesium is necessary for the proper functioning of muscle and nervous tissue. Symbol: Mg. m. carbonate a weak antacid used (usually in combination with other compounds) to relieve indigestion. m. hydroxide a magnesium salt used as an osmotic laxative and also as an ingredient in antacid preparations. m. sulphate a magnesium salt used in the form of mixtures or powders for rapid evacuation of the bowel (see laxative). It is also administered intravenously to treat magnesium deficiency and serious arrhythmias and to prevent recurrent convulsions in eclampsia. m. trisilicate a compound of magnesium with antacid and absorbent properties, used in the treatment of indigestion.

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"magnesium." A Dictionary of Nursing. . 12 Dec. 2017 <>.

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magnesium (symbol Mg) Silvery-white metallic element, one of the alkaline-earth metals. Magnesium's chief sources are magnesite and dolomite. Magnesium burns in air with an intense white flame, and is used in flashbulbs, fireworks, flares, and incendiaries. Magnesium alloys are light, and are used in aircraft fuselages, jet engines, missiles, and rockets. Chemically, the element is similar to calcium. Hydrated magnesium sulphate is called Epsom salts. Properties: 12; r.a.m. 24.312; r.d. 1.738; m.p. 648.8°C (1200°F); b.p. 1090°C (1994°F); most common isotope Mg24 (78.7%).

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"magnesium." World Encyclopedia. . 12 Dec. 2017 <>.

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mag·ne·si·um / magˈnēzēəm; -zhəm/ • n. the chemical element of atomic number 12, a silver-white metal of the alkaline earth series. It is used to make strong lightweight alloys, esp. for the aerospace industry, and is also used in flashbulbs and pyrotechnics because it burns with a brilliant white flame. (Symbol: Mg)

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"magnesium." The Oxford Pocket Dictionary of Current English. . 12 Dec. 2017 <>.

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magnesium An essential mineral; present in all human tissues, especially bone. Involved in the metabolism of ATP. Present in chlorophyll and so in all green plant foods, and therefore generally plentiful in the diet. Deficiency in human beings leads to disturbances of muscle and nervous system; in cattle, to grass tetany. Magnesium‐deficient plants are yellow (or chlorosed).

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"magnesium." A Dictionary of Food and Nutrition. . 12 Dec. 2017 <>.

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magnesium (Mg) An element that is found in high concentrations in plants. It plays an important role in the chemical structure of chlorophyll and of membranes and is involved in many enzyme reactions, especially those catalysing the transfer of phosphate compounds. Deficiency can produce various symptoms, including chlorosis and the development of other pigments in leaves.

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"magnesium." A Dictionary of Plant Sciences. . 12 Dec. 2017 <>.

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magnesium(Mg) An element that is found in high concentrations in plants. It plays an important role in the chemical structure of chlorophyll and of membranes and is involved in many enzyme reactions, especially those catalysing the transfer of phosphate compounds. Deficiency can produce various symptoms, including chlorosis and the development of other pigments in leaves.

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"magnesium." A Dictionary of Ecology. . 12 Dec. 2017 <>.

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magnesium Symbol Mg. A silvery metallic element that is an essential element for living organisms. It functions as a cofactor for various enzymes and is a constituent of chlorophyll in plants. In animals it is involved in the transmission of nerve impulses.

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"magnesium." A Dictionary of Biology. . 12 Dec. 2017 <>.

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magnesium •columbium •erbium, terbium, ytterbium •scandium • compendium •palladium, radium, stadium, vanadium •medium, tedium •cryptosporidium, cymbidium, idiom, iridium, rubidium •indium •exordium, Gordium, rutherfordium •odeum, odium, plasmodium, podium, sodium •allium, gallium, pallium, thallium, valium •berkelium, epithelium, helium, nobelium, Sealyham •beryllium, cilium, psyllium, trillium •linoleum, petroleum •thulium • cadmium •epithalamium, prothalamium •gelsemium, premium •chromium, encomium •holmium • fermium •biennium, millennium •cranium, geranium, germanium, Herculaneum, titanium, uranium •helenium, proscenium, rhenium, ruthenium, selenium •actinium, aluminium, condominium, delphinium •ammonium, euphonium, harmonium, pandemonium, pelargonium, plutonium, polonium, zirconium •neptunium •europium, opium •aquarium, armamentarium, barium, caldarium, cinerarium, columbarium, dolphinarium, frigidarium, herbarium, honorarium, planetarium, rosarium, sanitarium, solarium, sudarium, tepidarium, terrarium, vivarium •atrium •delirium, Miriam •equilibrium, Librium •yttrium •auditorium, ciborium, conservatorium, crematorium, emporium, moratorium, sanatorium, scriptorium, sudatorium, vomitorium •opprobrium •cerium, imperium, magisterium •curium, tellurium •potassium • axiom • calcium •francium • lawrencium • americium •Latium, solatium •lutetium, technetium •Byzantium • strontium • consortium •protium • promethium • lithium •alluvium, effluvium •requiem • colloquium • gymnasium •caesium (US cesium), magnesium, trapezium •Elysium • symposium

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