MgSO4·7H2O

Toxicity
Dust may irritate eyes or upper respiratory tract. May be harmful if swallowed. May act as an irritant. Adverse reactions include hypotension, ECG changes, diarrhea, urinary retention, CNS depression and respiratory depression, flushing, sweating, muscle weakness, dizziness, drowsiness, slowed/shallow breathing or other breathing trouble.
http://redpoll.pharmacy.ualberta.ca/drugbank/cgi-bin/getCard.cgi?CARD=APRD01080.txt

a.k.a.
Epsom salt, Magnesium sulfate heptahydrate, Magnesium sulfate, Magnesium hydroxide

 

Documentation