Low magnesium (serum)

Written to our editorial standards · reviewed against published research· Updated 2 Jun 2026

Low magnesium is linked to muscle cramps, poor sleep, anxiety, and palpitations, and the standard serum test often misses it because most magnesium sits inside cells.

Magnesium is involved in hundreds of reactions, including muscle relaxation, the stress response, and the GABA pathway that supports sleep. A serum magnesium can read normal even when body stores are low, so symptoms plus risk factors matter as much as the number. Glycinate is the gentle, well-absorbed form.

Common causes

  • Low intake of greens, nuts, and whole grains
  • Heavy alcohol use
  • Gut losses or diuretics
  • High stress
  • Type 2 diabetes

Associated symptoms

  • Muscle cramps and twitches
  • Poor sleep
  • Anxiety or feeling on edge
  • Palpitations
  • Headaches

Nutrients that can help

Magnesium Glycinate
See the guide →
What to do

Take magnesium glycinate in the evening, where it doubles as sleep support, and eat more magnesium-rich foods. Most people tolerate it well; citrate is more laxative.

When to see a doctor

Significant symptoms or known kidney disease should be reviewed by a doctor, since magnesium handling changes with kidney function.

Full marker
Magnesium (serum): ranges, what it measures & both directions
Read the Magnesium (serum) guide →

Common questions

What does low magnesium mean?
Low magnesium is linked to muscle cramps, poor sleep, anxiety, and palpitations, and the standard serum test often misses it because most magnesium sits inside cells. Magnesium is involved in hundreds of reactions, including muscle relaxation, the stress response, and the GABA pathway that supports sleep. A serum magnesium can read normal even when body stores are low, so symptoms plus risk factors matter as much as the number. Glycinate is the gentle, well-absorbed form.
What causes low magnesium (serum)?
Low intake of greens, nuts, and whole grains; Heavy alcohol use; Gut losses or diuretics; High stress; Type 2 diabetes.
How do I raise my magnesium (serum)?
Take magnesium glycinate in the evening, where it doubles as sleep support, and eat more magnesium-rich foods. Most people tolerate it well; citrate is more laxative.
When should I see a doctor?
Significant symptoms or known kidney disease should be reviewed by a doctor, since magnesium handling changes with kidney function.

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Educational use only, not medical advice or diagnosis. Reference ranges vary by lab, age, sex, and medication, and a single result is read in context. Always review your results with a qualified clinician.