A four-game suspension falls under Stage 2 of the NFL's policy, which means Scott has tested positive before. He will not be paid during the suspension.
Scott, a former fifth-round pick by Pittsburgh, was a backup guard who started eight games for Carolina in 2013. He was re-signed to a one-year deal earlier this year.
Scott will be eligible to return to the active roster Monday, Oct. 3, the day after Carolina faces the Atlanta Falcons.