The six-time Gold Glove winner, out since late February with pain in his lower back, was treated by Dr. Robin Dennings on Thursday after consulting with team orthopedist Dr. John Frazier earlier this week.
Chavez will need a minimum of two-to-three weeks of rehabilitation at the team's spring training facility in Phoenix before resuming baseball activities.
"At least (that long)," Oakland trainer Steve Sayles said before the A's game against Cleveland on Friday night. "He's returning to Phoenix and will go back into rehab. We're just going to take it from there."
Sayles said the second epidural was for spasms in the lower left side of Chavez's back. The first was for spasms on the right side.
"The right side had totally cleared up," Sayles said. "The left side then started acting up and so we wanted to address that. Once we're sure that the spasm hasn't returned then we'll start his baseball activities."
Chavez received his first epidural on Feb. 29, less than two weeks into spring training. He did not accompany the A's to Japan for their season-opening two-game series against Boston and has been relegated to getting therapy on his back.