This article is from the Mariah Carey FAQ, by Kade Hansson firstname.lastname@example.org with numerous contributions by others.
Most people assume not, and that assumption is true. However, a more
pertinent question is "Has she ever smoked?" This is a question that appears
only have ever been asked of Mariah by the public, and the answer is yes.
Mariah smoked during her teenage years, until the age of 18 when she gave up
in one day. Legend has it (and it is probably as good as any other
explanation) that just before she quit, Mariah lost her voice and promised
God she wouldn't smoke if she got it back. She did, so she doesn't.