My Friend Has Been Abusing Cough Syrup

my friend has been abusing the cough syrup medicine of choricidin, more commonly known as Triple C. I would like to know the signs of his addiction to look out for. It started as an occasional use for him but lately he has began taking it before school. It is started to scare me. I would also like to know the dangers of such a medication. Please contact me at Jaimacankid@hotmail.com
Thank you for your help
Your friend needs help now, before this gets out of control. Tell an adult what is going on, please.