The San Francisco 49ers placed linebacker Aldon Smith on the reserve/non-football injury list Monday.
Smith was arrested Friday on suspicion of DUI. He started Sunday's game against the Indianapolis Colts. He flew to a treatment center Monday, according to NBC Sports' Pro Football Talk. It is not clear where he headed, but he will spend the next several weeks getting treatment.
"Aldon Smith is taking a leave of absence to address a personal matter," general manager Trent Baalke said in a statement. "The 49ers organization both respects and supports Aldon's decision and commends him for taking responsibility for his actions. The long-term well-being of our players is paramount and we will stand by Aldon as he works toward addressing this issue. Due to the private nature of the matter, we will have no further comment."
Smith is out indefinitely, starting with Thursday's game at St. Louis.
"I am taking a leave of absence to address my health," Smith said in a statement. "I am sorry that I have affected my team, my family and the organization. I will do everything in my power to handle this situation the best way possible. I appreciate the support of the 49ers and our fans."
49ers head coach Jim Harbaugh declined to speculate whether Smith will play again this season.
"There's a process," said Harbaugh. "We're going to respect that process."
Team CEO Jed York announced after Sunday's 27-7 loss to the Colts that Smith would enter rehab.
Smith still could be suspended by the league at some point. York said there is no timetable for his return.
San Jose police Sgt. Heather Randol told ESPN that marijuana was not found in Smith's car but unidentified prescription drugs were after Smith crashed his car into a tree. He was arrested after the accident at 7 a.m. Friday. He was not injured.
"We're very fortunate that nobody got hurt, Aldon included and anybody else," York said. "We want to make sure that Aldon's never in a position like this again."
York said he discussed the situation with Smith, and he agreed to seek help.
"In talking with Aldon and knowing what he wants to do, there's not a one-day fix," he said. "This is a long-term fix. We support Aldon. If Aldon's willing to fight for himself and make this right, I will stand here and I will support him."
York was criticized by some for allowing Smith to play in Sunday's game.
"Sitting someone down and paying them to sit down when they're going to seek treatment in the future -- that didn't seem like an appropriate punishment," York said.
On Monday, Harbaugh declined to "rehash" the organization's decision.
"We did what we thought was in the best interest of the team and the best interest of the player long-term," he said.
Going forward, Dan Skuta, Ahmad Brooks and Corey Lemonier were among the players Harbaugh identified who could help fill Smith's pass-rushing role off the right side of the 49ers' defensive line.
"We got a pretty good idea of what we're gonna do," said Harbaugh.