Magnesium deficiency is widespread but often unrecognized due to limitations of standard testing. Serum magnesium reflects only a small fraction of body stores and may be normal even with significant deficiency. The signs of magnesium deficiency are often subtle and varied. This guide covers symptoms and considerations. Discuss with your healthcare provider.
Common symptoms
- Muscle cramps and twitches
- Fatigue
- Anxiety, irritability
- Insomnia
- Headaches, migraines
- Restless legs
- Tingling or numbness
- High blood pressure
- Heart palpitations
- Constipation
Risk factors
- Inadequate dietary intake
- GI losses (diarrhea, malabsorption)
- Diuretic use (loop and thiazide)
- Alcohol use
- Diabetes
- Long-term proton pump inhibitor use
- Refeeding syndrome
The testing problem
Only ~1% of body magnesium is in blood. Serum magnesium is tightly regulated and may be normal despite significant total body deficiency. RBC magnesium is more reflective but less commonly available. Many clinicians treat empirically based on symptoms. See our magnesium test guide.
Dietary sources
- Dark leafy greens
- Nuts and seeds (almonds, pumpkin seeds)
- Whole grains
- Legumes
- Dark chocolate
- Avocados
Supplementation
Common forms:
- Magnesium glycinate (well-absorbed, gentle on GI)
- Magnesium citrate (good absorption, mild laxative)
- Magnesium oxide (cheaper but poor absorption)
- Magnesium L-threonate (claims of brain bioavailability; limited evidence)
Typical dose: 200-400 mg daily. See our magnesium types guide.
Frequently Asked Questions
Can magnesium really cause anxiety?
Deficiency may contribute. Supplementation helps some patients with anxiety symptoms.
Why do I get muscle cramps?
Magnesium deficiency is one cause among many.
Should I supplement without testing?
Reasonable for symptoms suggesting deficiency. Testing has limitations.
Can I overdose on magnesium?
Difficult with oral supplementation. GI side effects (diarrhea) typically occur first.
What’s the best form?
Glycinate or citrate for most uses.
The bottom line on magnesium deficiency
Magnesium deficiency is common but underdiagnosed. Multiple symptoms possible. Testing has limitations. Empirical supplementation is reasonable for symptoms.