What is the recommended dosage and formulation of magnesium (magnesium oxide or magnesium citrate) for a patient with migraines and headaches?

Magnesium for Migraine Prevention

For migraine prevention, prescribe oral magnesium 600 mg daily (as trimagnesium dicitrate or magnesium oxide), taken continuously for at least 2-3 months before assessing efficacy. 1

Dosing and Formulation

• The recommended dose is 600 mg (24 mmol) of elemental magnesium daily, typically given as trimagnesium dicitrate, which has the strongest evidence from randomized controlled trials 2, 3
• Magnesium oxide is an acceptable alternative formulation when trimagnesium dicitrate is unavailable 1
• Continue treatment for a minimum of 2-3 months at therapeutic dosing before declaring treatment failure, as clinical benefits may not become apparent immediately 1

Evidence for Efficacy

• In a prospective, multicenter, double-blind, placebo-controlled trial of 81 patients, oral magnesium 600 mg daily reduced attack frequency by 41.6% compared to 15.8% with placebo (p < 0.05) 2
• The number of migraine days and symptomatic medication consumption also decreased significantly with magnesium supplementation 2
• The VA/DoD guidelines suggest oral magnesium for migraine prevention with a weak recommendation based on consistent evidence 1

Position in Treatment Algorithm

• The American College of Physicians recommends starting oral magnesium for patients with ≥2 migraine attacks per month producing disability lasting ≥3 days per month 1
• Magnesium ranks among other preventive options including topiramate, propranolol, and valproate, but sits below stronger recommendations for CGRP antagonists 1
• Magnesium offers unique advantages for use during pregnancy, in patients with cardiovascular disease, and provides a low-cost option with minimal side effects 1

Side Effects and Tolerability

• The most common adverse effects are diarrhea (18.6%) and gastric irritation (4.7%), which are generally mild and well-tolerated 2
• The side effect profile is considerably more favorable than many other migraine preventive medications 2, 3

Critical Clinical Pitfalls to Avoid

• Do not discontinue magnesium prematurely—allow the full 2-3 month trial period at therapeutic dosing before declaring treatment failure, as benefits may take time to manifest 1
• Do not use magnesium hydroxide liquid formulations (like Milk of Magnesia) for migraine prevention, as these are laxative preparations with different pharmacokinetics and are not the studied formulation 4
• For acute migraine treatment, IV magnesium sulfate 1 g may be effective, but only in patients with low serum ionized magnesium levels (<0.54 mmol/l); non-responders often have normal or elevated levels and should receive alternative acute treatments like triptans or NSAIDs 1, 5, 6

Prescription Example

• Magnesium oxide 400-500 mg tablets: Take 1-2 tablets daily (total 600 mg elemental magnesium) for migraine prevention 2
• Alternatively: Trimagnesium dicitrate 600 mg daily 2, 3