I think she meant she wants to try warning her friend herself - not that she wants to try inhalants herself! Simple misunderstanding.

She is doing permanent damage to both her respiratory system and central nervous system - see http://www.inhalants.org/damage.htm - which doesn't mention acetone specifically, but its links may. Just by inhaling that stuff she is damaging the delicate tissue in her nasal passages, which is probably why she's coughing - her nose can no longer act as a "filter" for things the way it normally would.