Best Magnesium for Migraine Prevention: Ranked by Form, Absorption, and Clinical Evidence

Magnesium functions as a gatekeeper at the NMDA glutamate receptor. Under normal physiological conditions, magnesium ions sit inside the receptor channel and block excessive calcium influx. When intracellular magnesium is depleted — a state that appears more common in people with frequent migraines — this block weakens, allowing glutamate-driven excitatory cascades to proceed more easily. The result is a lower threshold for cortical spreading depression, the slowly propagating wave of neuronal depolarization that underlies migraine aura and is now believed to be involved in non-aura attacks as well. Magnesium also plays a role in stabilizing serotonin receptors, regulating platelet aggregation, and influencing substance P release — all pathways implicated in migraine pathophysiology. Supplementation with highly bioavailable forms may help restore intracellular magnesium levels over weeks to months, gradually raising the neurological threshold needed to trigger an attack. This is why the timeline matters: magnesium doesn't work acutely the way a triptan does. It operates upstream, shifting the baseline biology that makes the brain migraine-prone in the first place.

The single most important variable in choosing a magnesium supplement for migraine prevention is form. Magnesium oxide — the version filling most pharmacy shelves — has a bioavailability of roughly 4%, meaning nearly all of what you swallow passes straight through. Glycinate, bisglycinate, and citrate forms absorb meaningfully better in most people. The glycinate chelates (including bisglycinate, which is just a name for the fully chelated version) bind magnesium to glycine molecules that survive stomach acid intact and are taken up through amino acid transport pathways in the small intestine. Citrate forms are absorbed through a different organic acid pathway and have the clinical trial precedent of the Peikert study behind them. Dosage is the second variable. Most published migraine trials used 400–600mg of elemental magnesium daily, usually split into two doses. When reading labels, the number that matters is elemental magnesium — not the total weight of the compound. A product listing 500mg of magnesium glycinate delivers less than 100mg of elemental Mg, because the glycine molecules make up most of the compound weight. Always check the "Amount Per Serving" of elemental magnesium, not the compound weight. Third-party testing matters more here than people realize. The supplement industry is largely self-regulated, and independent audits by organizations like NSF or USP verify that what's on the label is actually in the bottle — and that contamination with heavy metals or undisclosed ingredients is absent. For a supplement you'll be taking daily for six months, that's not a premium luxury. It's a reasonable expectation. Finally, think about the practical reality of a six-month trial. A format that's inconvenient — hard to travel with, unpleasant to take, or too expensive to maintain — will fail through non-adherence before you ever know whether the magnesium was working. Matching the format to your lifestyle is as clinically important as matching the form to the evidence.