pure dxm has same effects as as dxm found in cough meds. id say one 500mg pill will do the trick, and all the info and precautions at erowid applies also to pure dxm powder as well as the dxm found in cough meds.

*also make sure the dxm is in pill form, dont put the powder in your mouth it tastes like pure shit and it stays in your mouth for a while.