Donald Stephenson will be sitting out the first four games of the 2014 season. (USATSI)
Donald Stephenson will be sitting out the first four games of the 2014 season. (USATSI)

Kansas City Chiefs offensive lineman Donald Stephenson has been suspended for the first four games of the 2014 season after violating the NFL policy on performance-enhancing substances, the league announced on Friday. 

"Obviously losing Donald is disappointing, but we are in full compliance with the league's policy," the Chiefs said in a statement. "We will have no further comment on the situation."

The loss of Stephenson, who was expected to be the team's starting right tackle, is a big blow to a Chiefs' offensive line that was already lacking depth. Stephenson's suspension will likely mean a move to the starting lineup for Ryan Harris, but J'Marcus Webb could also play his way into the conversation. 

In a statement, Stephenson said he failed to get a 'therapeutic use exemption.'

"I'm extremely sorry that I failed to check with the NFL, NFLPA or Chiefs medical team before I took a medication that requires a therapeutic use exemption. The rules are strict and without a therapeutic use exemption, the consequence is a four-game suspension...

It is not a mistake I will ever make again."

The offensive lineman has played in all 32 regular season games for the Chiefs since the team selected him in the third round of the 2012 NFL Draft. Stephenson has started a total of 14 games for Kansas City, getting seven starts in both 2012 and 2013. 

Besides Stephenson, the Chiefs will also be missing Dwayne Bowe for one game. The wide receiver will miss the season opener after being given a one-game suspension last week for violating the league's substance-abuse policy.

Stephenson is eligible to play Kansas City's final two preseason games, he's also allowed to practice with the team from now until the preseason's over. The 25-year-old's suspension will begin just before Week 1 in September and Bailey will be eligible to return to the Rams' active roster on Sept. 30.