The Tampa Bay Buccaneers' running back announced the suspension in a statement on Wednesday. Martin said he plans to enter a treatment facility.
NFL Network Insider Ian Rapoport reported that Martin is being suspended for violating the league's performance-enhancing drugs policy. Per Rapoport, the violation is for Adderall, which is one of the issues the running back is battling.
"I was notified last week of a four-game suspension for violating the league's drug policy," Martin said in the statement. "My initial instinct was to appeal the suspension and finish the season with my teammates. However, after numerous discussions with people close to me -- including Coach (Dirk) Koetter -- I am starting the suspension immediately so I can enter a treatment facility and receive the help I truly need.
"On the field, I must be strong and determined to push through both pain and injuries to become an elite NFL running back. Off the field, I have tried that same approach in my personal life. My shortcomings in this area have taught me both that I cannot win these personal battles alone and that there is no shame in asking for help.
"I sincerely apologize to the Glazer family, General Manager Jason Licht and the entire Tampa Bay organization, my teammates and our tremendous fans. This was not the season I envisioned and I have let everyone down, including myself. However, adversity yields opportunity and I ask for your support in my battle to overcome these personal issues."
Martin missed practice Wednesday. The team said the absence was excused.
The starting running back was a healthy scratch in last week's loss to the Saints that all but dashed the Bucs' playoff hopes. Koetter told reporters Monday that the decision to bench Martin was tied to "trying to put the Bucs in the best position to win games."
Koetter never mentioned a potential suspension or off-field issue as the reason for Martin being scratched.
Rapoport reported the suspension starts this week -- not Week 16.
Martin missed six games after injuring his hamstring in Week 2. He struggled to find space in his return, averaging 2.77 yards per carry from Weeks 10-15. For the season, Martin averaged 2.9 yards per carry, lowest in the NFL for backs with at least 70 carries, per NFL Research. While he continued to run hard, Martin's production didn't live up to expectations.
The 27-year-old signed a five-year, $35.75 million contract, with $15 million guaranteed, in the offseason after finishing second in the NFL in rushing in 2015 with 1,402 yards.
"Doug has been a valued member of our organization for the past five seasons and we respect and support his decision to seek help," general manager Jason Licht said in a statement. "Right now, he is working through issues that are much larger than the game of football. Our primary concern is that he takes this time to focus on getting the help that he needs in order to move forward with his personal and professional life."
With one game left in the Bucs' season -- unless a miracle situation unfolds for Tampa to squeak into the playoffs -- Martin's suspension will wrap into the 2017 season.