There are a LOT of kids doing this. It is not 'normal', and it's definitely not safe, but it is commonplace.
I know literally 80-100 young people who regularly smoke cannabis or skunk - all my friends' kids as well as my son and his less 'respectable' friends. I know dozens who use m-cat, and more who have tried it once or twice.
My DS1 was similarly taking anything he could get his hands on at 15. Cannabis, skunk, m-cat, mushrooms, speed, cocaine, ecstasy, random pills... Tbh I am grateful I didn't know about most of it at the time, because just knowing about the skunk he was smoking - and then the m-cat at 17 - was worrying enough. He didn't care about school or his GCSEs, so underachieved, and spent a year or two messing about, getting stoned, and getting into trouble - including getting arrested on suspicion of burglary, because the police know that many young people who regularly take drugs are stealing to fund it. :(
I smoked cannabis myself and have tried other things, and have friends that use or have used various 'party drugs' without ruining their lives - so I was (am) quite pragmatic about drug use, and well informed and able to talk openly with my son (I recognise he doesn't always talk openly to me) and ask friends for advice when I've needed it.
My own DS has passed safely through a period of heavy use, thank goodness. The only hospital trip he's needed was for alcohol. He still smokes cannabis, but not daily, and rarely uses skunk. He doesn't use m-cat any more. He'd probably take other things if they were offered to him at a party...
I now have a few key thoughts...
Openness is safer than secrecy. (On the 2 occasions he has frightened himself, he has told me, so I have been able to help him).
Young people know drugs are dangerous. They just think they are invulnerable. And they think that drugs like cannabis are safer/less often dangerous than alcohol, or other accepted risks like driving motorbikes.
There are two types of users: those who take drugs to wind down from busy lives, and those who take drugs to switch off from lives they hate. Most of the young people in the first group keep themselves safe and are f