Section 02 · Monograph
Magnesium
Reviewed Nov 2026FDA label
supplementMineral supplement
- Forms
- Tab/Cap: 250-500mg elemental
- Dose
- 400-600mg/day elemental (prevention)
- MOA
- NMDA modulation; ↓cortical spreading depression
Indications
- Dietary supplement used for migraine prevention (supported by AAN/AHS evidence; not an FDA-approved drug)FDA-labeled
Mechanism of Action
- NMDA receptor modulation and reduced cortical spreading depression; correction of low magnesium levels reported in some migraine patients
Full Dosing
Adult / usual
- 400-600mg/day elemental magnesium (e.g., magnesium oxide 400-500mg/day, or glycinate/citrate) in divided doses with food
- Allow 2-3 months to assess benefit
Contraindications
- Severe renal impairment
- Myasthenia gravis (magnesium can worsen weakness)
- Heart block
Drug Interactions
- Reduces absorption of tetracyclines, fluoroquinolones, bisphosphonates and levothyroxine — separate by 2-4 hours
- Additive with magnesium-containing antacids and laxatives
Adverse Effects
- Diarrhea (dose-limiting)
- Abdominal cramping
- Hypermagnesemia in renal failure
Monitoring Parameters
- Renal function; serum magnesium if renal disease
Pregnancy & Lactation
- Considered safe at recommended dietary doses
- Compatible with breastfeeding