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Deficiency Guide

Magnesium deficiency

Symptoms, at-risk groups, and clinical context for magnesium deficiency. Sourced from NIH Office of Dietary Supplements and StatPearls.

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Subclinical magnesium inadequacy is common — an estimated 48% of Americans consume less than the EAR. Severe deficiency (hypomagnesemia, serum <0.75 mmol/L) is less common but significant in hospitalized patients and those on certain medications. Symptoms are often nonspecific, making it easy to miss.

Common symptoms

  • Muscle cramps, twitches, or spasms
  • Muscle weakness
  • Fatigue and low energy
  • Loss of appetite, nausea, or vomiting
  • Irritability, anxiety, or restlessness
  • Sleep disturbances
  • Headaches or migraines
  • Numbness or tingling
  • Abnormal heart rhythms (in severe deficiency)
  • Tremors

At-risk groups

  • Long-term proton pump inhibitor users (omeprazole, esomeprazole, lansoprazole)
  • People taking diuretics (furosemide, hydrochlorothiazide)
  • Older adults (decreased absorption, increased renal loss)
  • People with type 2 diabetes (urinary magnesium losses)
  • People with GI conditions (Crohn's, celiac, chronic diarrhea)
  • People with alcohol use disorder
  • Endurance athletes (sweat losses)
  • People eating predominantly processed foods (low magnesium intake)
When to see a doctorPersistent muscle cramps, unexplained anxiety with sleep problems, or symptoms in any at-risk group warrants a serum magnesium test. Note: serum levels reflect only ~1% of body magnesium and can be normal even when tissue stores are depleted; RBC magnesium or magnesium loading tests are more sensitive.
Sources: NIH ODS — Magnesium Health Professional Fact Sheet · Hypomagnesemia — StatPearls (NCBI Bookshelf NBK500003)
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Related deficiencies

Nutrients with overlapping symptoms — useful when investigating an unclear clinical picture.

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