I took 500 mg magnesium 12 hours ago. my heart is starting to have palpitations. is it dangerous? my hr is 62 also.

Magnesium safe but:: Magnesium is not dangerous and usually helps prevent palpitations. You don't say what form of Mag.; some forms like mag. oxide are very poorly absorbed and thus may have a laxative effect. Mag. taurate and glycinate are best absorbed. The palpitations are likely a coincidence. As for if they are dangerous, most are benign but can not tell for sure without an EKG. See http://tinyurl.com/78l5mvm