"Sometimes you don't feel it coming on for two hours, and you end up eating more. And sometimes the dose with these edibles is half a cookie, or a quarter of a cookie. And I don't know too many people who can eat only half a cookie," says Holland.
Part of it is the difficulty of gauging the dose; part of it is simple metabolism, she adds. "Your liver metabolizes THC into 11-hydroxy-THC, and 11-hydroxy-THC is very psychedelic. It's very altering."
Of course, for many people, getting "altered" is the whole point. A growing number of young people eschew joints and even Cannabis Cup-quality buds to get high inhaling the smoke from concentrated oils with a THC content of 50% or more.
"Some people are just interested in smoking gigantic amounts of marijuana," says Simunek.
The trend is hard to quantify, but there are countless YouTube videos of people smoking concentrates, and Thurstone says it's common among young people who enter his clinic.
"Most people are going to be fine," says Gitlow, the addiction specialist, "but there still will be that 10% of people who are going to get as high as they possibly can."