The Connection Between Magnesium and Headaches...
"Magnesium deficiency is believed to be present in 50% to 60% of people who suffer from migraines. However, a good 85% to 90% of migraine sufferers can often find immediate relief once they start taking supplements."
Office Of Dietary Supplements - Magnesium...
"Early signs of magnesium deficiency include loss of appetite, nausea, vomiting, fatigue, and weakness. As magnesium deficiency worsens, numbness, tingling, muscle contractions and cramps, seizures (sudden changes in behaviors caused by excessive electrical activity in the brain), personality changes, abnormal heart rhythms, and coronary spasms can occur [1,3-4].
Severe magnesium deficiency can result in low levels of calcium in the blood (hypocalcemia). Magnesium deficiency is also associated with low levels of potassium in the blood (hypokalemia) [1,19-20]."
Magnesium supplements, - to avoid,- how to take it and -safety:
http://www.medhelp.org/posts/Heart-Rhythm/Magnesium-supplements----to-avoid---how-to-take-it-and--safety/show/1002415