It is against the law to knowingly breathe, inhale, or drink a vapor-releasing toxic substance. Common things that fit this definition are glue, spray paint, gasoline, etc.
There are regulations regarding the sale of inhalants. Using or selling these substances is regarded as a class 5 felony or a class 1 misdemeanor depending on the seriousness of the offense (A.R.S. § 13-3403).
Laws may have changed since the last time this article was updated. The current and most up-to-date laws can be accessed here.