Overview

Magnesium is a mineral that is important for normal bone structure in the body. People get magnesium from food, but sometimes supplements are needed.

Magnesium is needed for many bodily functions. Low levels in the body have been linked to diseases such as osteoporosis, high blood pressure, and stroke. An easy way to remember foods that are good magnesium sources is to think of fiber. Foods that are high in fiber are generally high in magnesium.

People commonly use magnesium for constipation, as an antacid for heartburn, for low magnesium levels, for pregnancy complications called pre-eclampsia and eclampsia, and for a certain type of irregular heartbeat (torsades de pointes). It's also used for many other conditions, but there is no good scientific evidence to support many of these other uses.

Uses & Effectiveness

Effective for

  • Bowel preparation. Taking magnesium by mouth is helpful for preparing the bowel for medical procedures such as a colonoscopy.
  • Constipation. Taking magnesium by mouth is helpful as a laxative for short-term constipation.
  • 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 people with high blood pressure during pregnancy (eclampsia). Taking magnesium by IV or as a shot is considered the treatment of choice for eclampsia. Magnesium reduces the risk of seizures in people with this condition. But IV products can only be given by a healthcare provider.
  • Low levels of magnesium in the blood (hypomagnesemia). Taking magnesium supplements by mouth can treat and prevent magnesium deficiency.
  • A pregnancy complication marked by high blood pressure and protein in the urine (pre-eclampsia). Taking magnesium by IV or as a shot is considered the treatment of choice for preventing seizures from pre-eclampsia. But taking magnesium by mouth doesn't seem to reduce the risk of developing pre-eclampsia. IV products can only be given by a healthcare provider.

Likely Effective for

  • Cerebral palsy. Taking magnesium by IV when pregnant can reduce the risk of cerebral palsy in preterm infants. IV products can only be given by a healthcare provider.
  • Seizures. Taking magnesium by IV is helpful for treating various types of seizures. IV products can only be given by a healthcare provider.
  • A type of irregular heartbeat (torsades de pointes). Taking magnesium by IV is helpful for treating a certain type of irregular heartbeat called torsades de pointes. IV products can only be given by a healthcare provider.

Possibly Effective for

  • Irregular heartbeat (arrhythmias). Taking magnesium by IV or by mouth seems to help treat irregular heartbeat, also called arrhythmias. But it's not clear if taking magnesium helps reduce irregular heartbeat after heart surgery. IV products can only be given by a healthcare provider.
  • Asthma. Taking magnesium by IV seems to help treat sudden asthma attacks. But inhaling magnesium or taking magnesium by mouth doesn't seem to work. IV products can only be given by a healthcare provider.
  • Colon cancer, rectal cancer. Eating more foods with magnesium in them might reduce the risk of colon cancer, but not rectal cancer.
  • Diabetes. Eating a diet with more magnesium might reduce the risk of developing diabetes in adults and overweight children. But it's not clear if taking magnesium supplements helps.
  • High cholesterol. Taking magnesium by mouth appears to slightly decrease low-density lipoprotein (LDL or "bad") cholesterol levels and total cholesterol levels, and slightly increase high-density lipoprotein (HDL or "good") cholesterol levels in people with high cholesterol.
  • A grouping of symptoms that increase the risk of diabetes, heart disease, and stroke (metabolic syndrome). People with low magnesium levels are 6-7 times more likely to have metabolic syndrome than people with normal magnesium levels. Higher magnesium intake from diet and supplements is linked with a lower risk of developing metabolic syndrome.
  • Weak and brittle bones (osteoporosis). Eating more magnesium in the diet and taking magnesium supplements by mouth seems to prevent bone loss in older females with osteoporosis.
  • Pain after surgery. Taking magnesium with anesthesia or by IV after surgery seems to increase the amount of time before pain develops and might decrease the need to use pain relievers after surgery. IV products can only be given by a healthcare provider.
  • Premenstrual syndrome (PMS). Taking magnesium by mouth seems to relieve symptoms of PMS, including mood changes and bloating.
  • Chest pain due to blood vessel spasms (vasospastic angina). Taking magnesium by IV seems to prevent blood vessel spasms in people with chest pain caused by this condition. IV products can only be given by a healthcare provider.

Possibly Ineffective for

  • Altitude sickness. Taking magnesium citrate by mouth doesn't reduce the risk of altitude sickness.
  • Athletic performance. Taking magnesium by mouth doesn't increase energy or endurance during athletic activity.
  • Swelling (inflammation) of small airways in the lung (bronchiolitis). Giving magnesium by IV does not help and might even worsen bronchiolitis in infants. IV products can only be given by a healthcare provider.
  • Nerve damage in the hands and feet caused by cancer drug treatment. Taking magnesium does not prevent nerve damage caused by the cancer drug oxaliplatin.
  • Limb pain that usually occurs after an injury (complex regional pain syndrome). Taking magnesium by IV does not improve pain in people with chronic pain after an injury. IV products can only be given by a healthcare provider.
  • Confusion and agitation after surgery. Taking magnesium by IV does not seem to reduce delirium after surgery. IV products can only be given by a healthcare provider.
  • Symptoms of menopause. Taking magnesium oxide by mouth doesn't reduce hot flashes.
  • Muscle cramps. Taking magnesium supplements by mouth does not seem to decrease the frequency or intensity of muscle cramps.
  • Sickle cell disease. Giving magnesium sulfate by IV does not benefit children with sickle cell disease who are in the hospital. IV products can only be given by a healthcare provider.
  • Stillbirth. Taking magnesium supplements by mouth during pregnancy does not seem to decrease the risk of a stillbirth.
  • A hormonal disorder that causes enlarged ovaries with cysts (polycystic ovary syndrome or PCOS). Taking magnesium by mouth does not improve blood sugar, cholesterol, or hormone levels in people with PCOS.
  • A serious infection caused by Clostridium bacteria (tetanus). Taking magnesium by IV does not seem to reduce the risk of death in people with tetanus. IV products can only be given by a healthcare provider.
  • A sudden injury that causes damage to the brain (traumatic brain injury). Treatment with magnesium does not improve the outcome or reduce the risk of death for people with a traumatic brain injury. It's not clear if taking magnesium by mouth is helpful in people with a concussion.

There is interest in using magnesium for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Side Effects

When taken by mouth: Magnesium is likely safe for most people. 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 doses 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.

Special Precautions and Warnings

Pregnancy and breast-feeding: Magnesium is likely safe for those pregnant or breast-feeding when taken by mouth in doses less than 350 mg daily. Magnesium is possibly unsafe when taken by mouth in doses greater than 350 mg daily. High doses can cause diarrhea and too much magnesium in the blood.

Children: Magnesium is likely safe when taken by mouth in daily doses of 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.

Alcohol use disorder: Alcohol abuse increases the risk for magnesium deficiency.

Bleeding disorders: Magnesium seems to slow blood clotting. Taking magnesium might increase the risk of bleeding or bruising in people with bleeding disorders.

Diabetes: Diabetes increases the risk for magnesium deficiency.

Kidney conditions: 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.

Interactions

    Moderate Interaction

    Be cautious with this combination

  • Antacids interacts with Magnesium

    Antacids might reduce the laxative effects of magnesium. People taking magnesium as a laxative might require a higher dose.

  • Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs) interacts with Magnesium

    Magnesium might slow blood clotting. Taking magnesium along with medications that also slow blood clotting might increase the risk of bruising and bleeding.

  • Digoxin (Lanoxin) interacts with Magnesium

    Digoxin helps the heart beat more strongly. Magnesium might decrease how much digoxin the body absorbs. This might decrease the effects of digoxin.

  • Antibiotics (Aminoglycoside antibiotics) interacts with Magnesium

    Some antibiotics can affect the muscles. These antibiotics are called aminoglycosides. Magnesium can also affect the muscles. Taking these antibiotics and getting a magnesium shot might cause muscle problems.

  • Antibiotics (Quinolone antibiotics) interacts with Magnesium

    Magnesium might decrease how much antibiotic the body absorbs. Taking magnesium along with some antibiotics might decrease the effectiveness of some antibiotics. To avoid this interaction, take these antibiotics at least 2 hours before, or 4 to 6 hours after, magnesium supplements.

  • Antibiotics (Tetracycline antibiotics) interacts with Magnesium

    Magnesium might decrease how much antibiotic the body absorbs. Taking magnesium along with some antibiotics might decrease the effectiveness of some antibiotics. To avoid this interaction, take these antibiotics at least 2 hours before, or 4 to 6 hours after, magnesium supplements.

  • Bisphosphonates interacts with Magnesium

    Magnesium can decrease how much bisphosphate the body absorbs. Taking magnesium along with bisphosphates can decrease the effectiveness of bisphosphate. To avoid this interaction, take bisphosphonate at least 2 hours before magnesium or later in the day.

  • Medications for high blood pressure (Calcium channel blockers) interacts with Magnesium

    Some medications for high blood pressure work by blocking calcium from entering cells. Magnesium might also block calcium from entering cells. Taking magnesium with these medications might cause blood pressure to go too low.

  • Muscle relaxants interacts with Magnesium

    Magnesium seems to help relax muscles. Taking magnesium along with muscle relaxants can increase the risk of side effects of muscle relaxants.

  • Water pills (Potassium-sparing diuretics) interacts with Magnesium

    Some "water pills" can increase magnesium levels in the body. Taking some "water pills" along with magnesium might cause too much magnesium to be in the body.

  • Bictegravir/Emtricitabine/Tenofovir Alafenamide (Biktarvy) interacts with Magnesium

    Magnesium can decrease how much bictegravir/emtricitabine/tenofovir alafenamide the body absorbs from the stomach. To avoid this interaction, take bictegravir/emtricitabine/tenofovir alafenamide at least 2 hours before or 6 hours after magnesium containing products.

  • Levodopa/Carbidopa (Sinemet) interacts with Magnesium

    Levodopa/carbidopa is used for Parkinson disease. Taking magnesium oxide along with levodopa/carbidopa might decrease the effectiveness of levodopa/carbidopa. Do not take magnesium oxide if you are taking levodopa/carbidopa.

  • Ketamine (Ketalar) interacts with Magnesium

    Ketamine is used for severe pain and depression. Taking large doses of magnesium along with ketamine might increase the effects and side effects of ketamine.

    Minor Interaction

    Be watchful with this combination

  • Gabapentin (Neurontin) interacts with Magnesium

    Magnesium might decrease how much gabapentin the body absorbs. This might decrease the effects of gabapentin. Take gabapentin at least 2 hours before, or 4 to 6 hours after, taking magnesium supplements.

  • Sevelamer (Renagel, Renvela) interacts with Magnesium

    Sevelamer can increase magnesium levels in the body. Taking sevelamer with a magnesium supplement might cause magnesium levels to get too high.

  • Medications for diabetes (Sulfonylureas) interacts with Magnesium

    Magnesium hydroxide might increase how much sulfonylurea the body absorbs. By increasing how much sulfonylurea the body absorbs, magnesium hydroxide might increase the risk of low blood sugar in some patients.

Dosing

Magnesium is an important nutrient. The amount that should be consumed on a daily basis is called the recommended dietary allowance (RDA). The RDA depends on age and gender for both adults and children, and is also different when pregnant or breast-feeding. For adult males, the RDA is 400-420 mg daily, depending on age. For adult females, the RDA is 310-320 mg daily, depending on age.

Magnesium supplements vary depending on the particular salt form used (magnesium aspartate, magnesium citrate, magnesium oxide, etc.). It's also available in many multivitamin products. Speak with a healthcare provider to find out what type of product and dose might be best for a specific condition.
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