I take over a 1000mg a day. But you can't start at this dose. it takes time to work up to it. it's also important to use the right type- I like mag glycinate and mag malate.
Are You Suffering From Magnesium Deficiency?
When I first started Rogaine it made my head itch like crazy. Hubby said I scratched in my sleep too. Thankfully it stopped after a couple months.