If you can heat the active components enough to become aerosolized without starting a combustion reaction with the other compounds, then you theoretically get fast effects without the damage of smoke inhalation.
In the case of marijuana, the active component THC is aerosolized and follows the same pathway into your body, but with different effects which we explain in our video" Your Brain on Marijuana" here.
It can be spread by vomiting and because it can aerosolize to some extent, people can pick up enough that way, it can be spread through the stool if you accidentally get a little bit of feces on something.