I would recommend reading on it if you are planning on doing higher doses.

http://www.third-plateau.org/faq/dxm_faq.shtml

That is a great site with lots of info on it. It is better to be informed when trying things then doing them blindly I think.
rnf232s Reviewed by rnf232s on . Equate Tussin DM Hey, I dont have any robitussin or coricidin. I found a brand new unopen bottle of equate tussin DM cough suppressant expectorant. would this work. The bottle is 4 FL OZ. how much would i take? It says active ingredients Dextromethorphan HBr, USP 10mg **also, at the top it says "Compare to Robitussin DM active ingredients"...if that means anything Rating: 5