Erowid has good info. Check out the web links there too. There is a dosage chart somewhere on there. Best to get Robotussin Extra Strength Cough or other containing only DXM. Keep in mind that this shit is very strong. Last time I drank (2) 4oz. bottles. I weigh 225lbs. I was debilitated for several hours. At one point had semi-paralysis, couldn't walk or talk. I suggest (1) 4oz. bottle for a good trip. 8oz. was too strong for me, stronger than acid, and I used to do alot of that. Be safe on that stuff and in a good mood when you do it.