Drug Abuse Center

I'm Suspicious That My Best Friend Has Been Abusing Lithium. I've Seen Her Acting Funny But I Want To Get The Facts About It Before I Accuse Her. I've Tried Looking Around Online But Am Not Finding What I Would Like To Know About It. How Do You Abuse Lithium? And How Much Do You Have To Take To Mess You Up? I Know She Is Perscribed It And I Don't Want To Accuse Her If She's Just Taking How She's Suposed To But I Know Nothing About The Drug.
Any Help Please?