(CNN) - Charlie Sheen's ex-wife Brooke Mueller is back in rehab.
Mueller's lawyer Yale Galanter says his client checked in Tuesday night, and says her visit is not for any illegal substances.
He says she has a prescription for Adderall and did not like the way it made her feel, so she decided to check into rehab.
Adderall is a stimulant medicine used to treat ADHD, according to the Food and Drug administration.
Brooke Mueller has two children with Charlie Sheen.
TMZ reports this is Mueller's 19th stint in rehab.