The Aerosmith frontman, who was thought to have been clean and sober after beating drug addiction 20 years ago, issued a statement last month saying he entered the California rehab facility for a "safe environment" in which to recover from foot surgery.
Now the 60-year-old singer has said that he was really fighting dependency on painkillers and sleep medication.
"To have your feet done, to have your leg done, you have to be on narcotics," Tyler told the Associated Press. "You have to be on sleep aids at night. I don't know about (guitarist) Joe (Perry) but I was off and running and I didn't like the me that was me.
"This was a month ago, so I just put the brakes on and checked into detox and just pulled the plug on all of it," Tyler added.
Aerosmith wrapped up a world tour last year and intend begin recording a new album this year.

nme.com