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Magnesium deficiency

5-minute read

Key facts

  • Magnesium deficiency is when your body does not get enough magnesium in your diet to function normally.
  • Magnesium is a mineral essential for healthy muscles, nerves, bones and blood sugar levels.
  • Health problems linked to magnesium deficiency are rare, but they can occur if you have low levels of magnesium in your body for a long time.
  • Symptoms of magnesium deficiency include low appetite, nausea or vomiting, muscle spasms or tremors and abnormal heart rhythms.
  • Magnesium deficiency is usually treated with supplements.

What is magnesium?

Magnesium is a mineral that is essential for healthy muscles, nerves, bones and blood sugar levels.

What is magnesium deficiency?

Magnesium deficiency is when your body does not get enough magnesium in your diet to function normally.

Read more on magnesium and your health.

What are the symptoms of magnesium deficiency?

Magnesium deficiency can cause:

What causes magnesium deficiency?

Magnesium deficiency is rare in healthy people.

In some people, it can be caused by:

How is magnesium deficiency diagnosed?

Magnesium deficiency can be diagnosed with a blood test and/or a urine test. If you have symptoms of magnesium deficiency or abnormal calcium or potassium levels, your doctor may refer you for a blood or urine test.

How is magnesium deficiency treated?

Magnesium deficiency is usually treated with magnesium supplements. Sometimes these can give you diarrhoea, so your doctor may need to adjust your dose. If your levels are very low, you may need magnesium through an intravenous (IV) drip in hospital.

If you are considering taking a magnesium supplement, speak to your doctor or pharmacist first, to make sure it's right for you.

Read more on the role of foods high in magnesium and how supplements can prevent magnesium deficiency.

Magnesium poisoning

Rarely, people experience magnesium poisoning, or toxicity, which is when they have too much magnesium. Symptoms of magnesium toxicity include vomiting, diarrhoea and abdominal (stomach) cramps. In extreme cases, too much magnesium can cause an irregular heartbeat and cardiac arrest (when the heart stops beating).

Magnesium toxicity usually only happens if you take large quantities of magnesium in the form of magnesium supplements, antacids or laxatives. You can reduce the chance of this happening by taking medicines exactly as directed by your doctor or pharmacist.

How is magnesium deficiency prevented?

To prevent magnesium deficiency, eat a healthy, balanced diet containing magnesium-rich foods. These include:

  • leafy green vegetables
  • legumes
  • nuts and seeds
  • whole grains

What are the complications of magnesium deficiency?

Health problems linked to magnesium deficiency are rare. If your magnesium levels are low for a long period of time, you may be at greater risk. This could be because of health conditions such as alcoholism or because you are taking certain medicines.

In the short-term, severe magnesium deficiency can lead to:

  • muscle spasms
  • abnormal heart rhythms (arrhythmias)
  • cardiac arrest

Long-term magnesium deficiency can increase your chance of developing health problems, including:

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Last reviewed: June 2023

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