What Is Hypomagnesemia?

Medically Reviewed by Dan Brennan, MD on February 20, 2024
Written by Susan Adcox
3 min read

Hypomagnesemia means you have a low level of magnesium in the blood. 

Magnesium is a mineral that is very important for health. Your body contains about 25 grams of magnesium. Most of it is in your bones and soft tissues. Only about 1% is in your blood. The easiest way to measure magnesium in the body is to test the blood. If the level of magnesium in your blood falls below 0.75 mmol/L, you have low magnesium or hypomagnesemia.

Hypomagnesemia can be caused by a low intake of magnesium. It can also happen when too much magnesium is lost through the kidneys or intestines. The following groups are at high risk for losing too much magnesium in this way:

  • People with gastrointestinal problems such as Crohn's disease or celiac disease
  • People with type 2 diabetes, whose kidneys typically excrete more urine
  • Those who overuse alcohol, causing problems with the kidneys and digestive system

Hypomagnesemia may also result from the use of certain medications:

  • Some diuretics, which are used to help the body get rid of excess fluid and salt
  • Proton pump inhibitors, which treat acid reflux
  • A class of antibiotics known as aminoglycosides
  • Amphotericin B, a medicine used to treat fungal infections
  • Digitalis, a heart medication
  • Certain chemotherapy drugs

Symptoms of hypomagnesemia include:

  • Nausea and/or vomiting
  • Weakness and sleepiness
  • Personality changes
  • Muscle spasms or tremors
  • Loss of appetite 

Doctors may also suspect hypomagnesemia if a person has low levels of calcium and potassium in the blood.

When magnesium is so low that it causes symptoms, doctors give magnesium intravenously. They may prescribe oral magnesium as a follow-up treatment. Hypomagnesemia treatment should also include addressing the underlying cause.

When magnesium levels are slightly low and do not cause symptoms, treatment may not be necessary. In hospitalized patients, low magnesium levels should be addressed as part of total nutrition management. Those who are being fed through a vein may need magnesium supplements.

It's unclear whether treatment is necessary for those with diabetes who have mild hypomagnesemia. At least one study found that those with low magnesium are at greater risk of diabetes complications, such as foot ulcers, vision problems, and a decrease in kidney function. Some experts believe hypomagnesemia worsens insulin resistance, which in turn worsens hypomagnesemia, creating a downward spiral.

Food is the best way to meet the body's need for magnesium. The following foods are rich in magnesium:

If you choose to take magnesium supplements, stay below the upper limit for magnesium supplementation, which is 350 mg for most adults. High doses of magnesium can be dangerous. 

For most people, the risk of hypomagnesemia is about 2%. The risk is higher for certain groups. Hospitalized patients have a 10% to 20% chance of hypomagnesemia. That risk rises to about 50%-60% for people in hospital intensive care units. People with diabetes have about a 25% chance of hypomagnesemia, and those who overuse alcohol have a 30%- 80% risk.

If left untreated, hypomagnesemia can cause the heart to beat irregularly. You could be especially at risk for torsades de pointes, a type of arrhythmia (uneven heartbeat).  

Low levels of magnesium could also increase your risk of:

  • Heart disease. Some studies show that people who have enough magnesium in their diets are at a lower risk of heart disease and stroke. 
  • Type 2 diabetes. People with higher levels of magnesium have a lower risk of insulin resistance, which can lead to type 2 diabetes.
  • Osteoporosis (thinning bones). Magnesium is important for bone density. Low magnesium is related to osteoporosis, which can increase your risk of bone fractures.
  • Migraine headaches. Those who have migraine headaches sometimes have low magnesium. They may be able to reduce their headache frequency by taking magnesium supplements under the supervision of a doctor.