@Peatful honestly, I can’t tell you what to say. My parents tried to stop me but I was hardheaded about it and just became deceitful. I thought it was perfectly safe and ignored their loving attempts to correct my behavior. (“its like… a natural plant mannnn”)
I had to learn the hard way when I became too sick, lazy, and retarded to function.
From a place of full sincerity, I think the teenage urge towards psychoactive drugs is just a desire for novelty. I don’t know how open-minded you are, but one option would be trying to redirect her desire for such novelty onto a different, less harmful substance such as psilocybin or other mild psychedelic. Which would be self-limiting as they only “work” for a few hours once every several weeks. She’ll still feel “cool” but it won’t interfere with her schooling or brain development.
Ray spoke positively about similar substances, and I actually made good use of them to help my autism and I would even say they helped me reverse some of the damage done by THC…
If that’s out of the question, (reasonable), there’s really nothing you can do short of impressing the hormonal impact. I’m sure a teenage girl might receive poorly the information that THC damages your metabolism and could make her gain weight. She might also not like the potential long term fertility effects if she has any inclination towards being a mother. (Weed babies come out a bit retarded)
On nicotine/vapes, just impress the reality that these things are totally new tech and have untested ingredients, and potential for heavy metal exposure (and all the associated diseases).
Also just coming from a regular nicotine user due to dependence, holy shit is it an expensive fucking habit.