Experts say that many people in the U.S. aren’t eating enough foods with magnesium. Adults who get less than the recommended amount of magnesium are more likely to have elevated inflammation markers. Inflammation, in turn, has been associated with major health conditions such as heart disease, diabetes, and certain cancers. Also, low magnesium appears to be a risk factor for osteoporosis.
There’s some evidence that eating foods high in magnesium and other minerals can help prevent high blood pressure in people with prehypertension.
Intravenous or injected magnesium is used to treat other conditions, such as eclampsia during pregnancy and severe asthma attacks. Magnesium is also the main ingredient in many antacids and laxatives.
Serious magnesium deficiencies are rare. They’re more likely in people who:
- Have kidney disease
- Have Crohn’s disease or other conditions that affect digestion
- Have parathyroid problems
- Take certain drugs for diabetes and cancer
- Are older adults
- Abuse alcohol
Health care providers sometimes suggest that people with these conditions take magnesium supplements.
Proton pump inhibitors (PPIs), a common type of medicine used to treat acid reflux, have also been tied to low magnesium levels. Examples of PPIs include dexlansoprazole (Dexilant), esomeprazole (Nexium), lansoprazole (Prevacid), omeprazole (Prilosec, Zegerid), pantoprazole (Protonix), and rabeprazole (Aciphex). If you take any of these medicines on a long-term basis, your health care provider may check your magnesium level with a blood test.
Magnesium Recommended Daily Allowance
The recommended dietary allowance (RDA) includes the magnesium you get from both the food you eat and any supplements you take.
Uses & Effectiveness
- Constipation. Taking magnesium by mouth is helpful as a laxative for constipation and to prepare the bowel for medical procedures.
- Indigestion (dyspepsia). Taking magnesium by mouth as an antacid reduces symptoms of heartburn and indigestion. Various magnesium compounds can be used, but magnesium hydroxide seems to work the fastest.
- Seizures in women with pre-eclampsia. Administering magnesium intravenously (by IV) or as a shot is considered the treatment of choice for eclampsia. Administering magnesium reduces the risk of seizures in women with this condition.
- Low levels of magnesium in the blood (hypomagnesemia). Taking magnesium is helpful for treating and preventing magnesium deficiency. Magnesium deficiency usually occurs when people have liver disorders, heart failure, vomiting or diarrhea, kidney dysfunction, and other conditions.
- A pregnancy complication marked by high blood pressure and protein in the urine (pre-eclampsia). Administering magnesium intravenously (by IV) or as a shot is considered the treatment of choice for preventing seizures in women with pre-eclampsia. But taking magnesium by mouth doesn’t seem to reduce the risk for pre-eclampsia in healthy women.
- Foot sores in people with diabetes.
- Hay fever.
- Lyme disease.
- Skin infections.
- Urinary incontinence.
- Other conditions.
Side Effects & Safety
When taken by mouth: Magnesium is LIKELY SAFE for most people when taken by mouth appropriately. Doses less than 350 mg daily are safe for most adults. In some people, magnesium might cause stomach upset, nausea, vomiting, diarrhea, and other side effects. When taken in very large amounts (greater than 350 mg daily), magnesium is POSSIBLY UNSAFE. Large doses might cause too much magnesium to build up in the body, causing serious side effects including an irregular heartbeat, low blood pressure, confusion, slowed breathing, coma, and death.
When given as a shot or by IV: Magnesium is LIKELY SAFE for most people when the prescription-only, injectable product is used correctly by a healthcare provider.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Magnesium is LIKELY SAFE for pregnant or breast-feeding women when taken by mouth in doses less than 350 mg daily. Magnesium is POSSIBLY SAFE when the prescription-only, injectable product is given by IV or as a shot for up to 5 days before delivery. But prescription-only magnesium is given only to pregnant women with certain serious health conditions. There is evidence that using magnesium to suppress early labor might cause serious problems in the infant. Magnesium is POSSIBLY UNSAFE when taken by mouth in high doses or when the prescription-only, injectable product is given by IV or as a shot for longer than 5 days. Taking magnesium by mouth in high doses can cause diarrhea and too much magnesium in the blood. Receiving prescription-only magnesium by IV or as a shot for longer than 5 days might cause bone and brain problems in the infant.
Children: Magnesium is LIKELY SAFE for most children when taken by mouth appropriately or when the prescription-only, injectable product is used correctly. Magnesium is safe when taken by mouth in doses less than 65 mg for children 1-3 years, 110 mg for children 4-8 years, and 350 mg for children older than 8 years. Magnesium is LIKELY UNSAFE when taken by mouth in higher doses.
Alcoholism: Alcohol abuse increases the risk for magnesium deficiency.
Bleeding disorders: Magnesium seem to slow blood clotting. In theory, taking magnesium might increase the risk of bleeding or bruising in people with bleeding disorders.
Diabetes: Diabetes increases the risk for magnesium deficiency. Poorly controlled diabetes reduces how much magnesium the body absorbs.
Elderly: The elderly are at risk for magnesium deficiency due to reduced magnesium absorption by the body and often the presence of diseases that also affect magnesium absorption.
Heart block: High doses of magnesium (typically delivered by IV) should not be given to people with heart block.
Diseases that affect magnesium absorption: How much magnesium the body absorbs can be reduces by many conditions, including stomach infections, immune diseases, inflammatory bowel disease and others.
A condition called myasthenia gravis: Magnesium given intravenously (by IV) might worsen weakness and cause breathing difficulties in people with a condition called myasthenia gravis.
Kidney problems, such as kidney failure: Kidneys that don’t work well have trouble clearing magnesium from the body. Taking extra magnesium can cause magnesium to build up to dangerous levels. Don’t take magnesium if you have kidney problems.
A disorder that causes a strong urge to move ones legs (restless legs syndrome; RLS): People with restless legs syndrome might have high magnesium levels. But it’s not clear if magnesium is the cause for this condition, as people with restless legs syndrome have also had magnesium deficiency.
The following doses have been studied in scientific research:
- General: The daily Recommended Dietary Allowances (RDA) for elemental magnesium are: 19-30 years, 400 mg (men) and 310 mg (women); 31 years and older, 420 mg (men) and 320 mg (women). For pregnant women age 14-18 years, the RDA is 400 mg; 19-30 years, 350 mg; 31-50 years, 360 mg. For lactating women age 14-18 years, the RDA is 360 mg; 19-30 years, 310 mg; 31-50 years, 320 mg. The daily upper intake level (UL) for magnesium is 350 mg for anyone over 8 years old, including pregnant and breast-feeding women.
- General: The daily Recommended Dietary Allowances (RDA) for elemental magnesium are: Age 1-3 years, 80 mg; 4-8 years, 130 mg; 9-13 years, 240 mg; 14-18 years, 410 mg (boys) and 360 mg (girls). For infants less than one year of age, adequate intake (AI) levels are 30 mg from birth to 6 months and 75 mg from 7 to 12 months. The daily upper intake level (UL) for magnesium is 65 mg for children age 1-3 years, and 110 mg for 4-8 years.