just look on the back of whatever you buy and make sure that the only active ingredient is DXM HBr. avoid DXM polistirex and syrups with any other active ingredients besides DXM Hbr. i think the robo cough gels are a DXM-only product but as the above poster mentions, they're more expensive than syrup.
Dxm polistirex isn't bad for you as long as its the only active ingredient and delsym USUALLY only contains dxm polisti polistirex is ana edible plastic designed for ime believe something withthat absorption but tablets containing only dxm 3c's especially off brand 3c's are good too