Answer:
When it comes to alcohol abuse, honestly there are a million consequences for teens who begin to experiment.
For example, for people who drink and drive they can get arrested and in more extreme cases get in an accident.
They can change both physically and mentally - getting actually addicted to the substance and actually end up in rehabilitation.
Another instance is they could lose friends, or even close family because of their alcohol abuse. Could be because of behavioral issues or even because their use is pushing their relationships apart. They can get incredibly dependent and when it comes to chosing - many won't make the right choice.
You can lose your license, or unintentionally hurt someone else mentally or physically - which again, can land you in your own cell in jail.
If you need anymore examples, let me know! (: I hope this helped, and all is well! good luck, rockstar!