Veteran tackle Brentson Buckner of the Carolina Panthers was suspended four games Monday for violating the NFL's steroids abuse policy.

The much-traveled Buckner, in his ninth season in the league, has helped turn Carolina's unit into one of the league's best defensive lines.

Buckner's agent, George Mavrikes, said Buckner took a diet pill before training camp with an ingredient that's on the league's list of banned substances.

"It was all-organic, all-natural, and that's where you get into trouble,'' Mavrikes said. "He didn't really think that by taking a diet pill it would be banned, because it was not a performance enhancer.

"He just wanted to lose a little weight before camp, but unfortunately, the NFL treats diet pills the same as steroids.''

Buckner had started all eight games this season and had 23 tackles, four sacks and three pass deflections. With Sean Gilbert lost for the season because of a fractured hip, the Panthers are perilously thin on the line after enjoying one of the league's top tackle rotations early in the season.

Buckner, 31, will be eligible to return to the team after its Dec. 1 game at Cleveland. During the suspension, Buckner cannot work out at Carolina's facility and cannot have contact with team officials.

The suspension will cost him $164,705. His base salary this season is $700,000.

Buckner has appeared in 127 games in his career, starting 80 of them, in stints with Pittsburgh (1994-96), Cincinnati (1997), San Francisco (1998-2000) and the Panthers (2001-2002). The former Clemson standout has 317 tackles, 25 sacks, three forced fumbles, one interception and 24 pass deflections.

The Panthers had a bye on Sunday.

Shane Burton, who will start in Buckner's place, said Buckner told him during Carolina's bye week that he might be out.

"He gave me the heads-up that he might be out so I've been getting ready for about a week-and-a-half,'' Burton said. "He knew that there was a chance, so he just told me to be ready.''

Carolina punter Todd Sauerbrun complained Monday that the league is too strict about what the players can take, saying the NFL "treats us like babies.''

And defensive end Mike Rucker said even cold medicine has to be checked out by the team before a player takes it.

Len Pasquarelli is a senior writer for ESPN.com. Information from The Associated Press was used in this report.