Many antacids or laxatives also contain magnesium. It is sometimes given IV during pregnancy to control eclamptic seizures and to inhibit uterine motility during premature labor. Large doses can lower blood pressure and cause depression of the central nervous system. Recently magnesium supplements have gained popularity for several unapproved uses. Many patients with migraine headaches have been found to have low levels of magnesium ions.
Magnesium supplements appear to decrease the incidence of migraine attacks in certain people.
Oral magnesium may be helpful in preventing premenstrual or menstrual migraines. It may also minimize premenstrual mood changes and fluid retention. When used IV under medical supervision, magnesium may be used to treat cluster migraines. Magnesium supplements should only be used under medical supervision in the presence of heart disease or kidney impairment. A deficiency of magnesium is rare.