Some of the responses in this thread are just fucking asinine. Who are you all to critique his choice of drug? If you're going to say the "highest safe dose" of DXM is 60-100mg, then by that logic it makes just as much sense to say that the highest safe dose of DXM is 0mg. Harm reduction doesn't mean giving silly, trite answers to questions. It means you acknowledge the fact that the OP
will take more than the "medically appropriate" dose, because it is his INTENTION to get fucked up. Therefore, according to harm reduction, we should give him the average dose to achieve what he wants to achieve that will not kill him. /rant
DXM does not follow a standard dose/response curve where the effects are always the same, but get stronger when you take more. DXM has plateaus of effect based on dose that are vastly different from one another. The dose you want to take depends on the effects you want. First and second plateau doses are similar to intoxication from alcohol. Third plateau doses are intensely psychedelic, with intensity depending on where you dose in the third plateau "window" of dosage. The fourth plateau typically leads to a sort of unconsciousness where you are tripping inside your own head, and not really aware of the outside world. Above that is dissociative anesthesia, where you are pretty much in a coma, and above that is overdose and death.
Section 5 of the DXM FAQ on Erowid describes each of the plateaus in detail, so you can pick the one that appeals most to you. I really enjoy third plateau doses, and now take them exclusively if I'm going to use DXM. Different people enjoy different things. I would not recommend charging right into a fourth plateau dose or a plateau sigma dose (read the FAQ for details) without first getting some experience with lower doses. The very first part of that FAQ also lists suggested doses for each plateau.
DXM dosage varies according to your weight. For example, the recommended third plateau dose is 7.5-15mg/kg, which I'm sure you can see is a very broad dosage window. If you wanted to try 8mg/kg then start by converting your body weight to kilograms. 200 pounds ~= 90 kg. 90 * 8 (mg/kg) = 720mg.
This is pretty close to what you'd get from 1 355ml bottle of syrup containing DXM at 2mg/ml, which is common for preparations containing Guaifenesin. Guaifenesin is an expectorant that can make you sick to your stomach at high doses. You can either try to soldier through it, or (recommended!) perform a simple extraction on the syrup. You can get more info on this by searching for "dxm agent lemon" or "agent lemon extraction". If you have any questions feel free to PM me.
Mods might consider a move to BDD...
