According to ProFootballTalk.com, Gordon tested positive for alcohol. If Gordon did fail, he could be suspended for the entire 2015 season.
ESPN first reported Gordon's failed test.
The Browns released a statement regarding the reports: "Clearly we are very disappointed to hear the latest report regarding Josh. At this point, due to the confidential nature of the NFL's substance-abuse policy, we have not been made aware by the league of a failed test. We are in the process of gathering more information and will provide further comment at the appropriate time."
Gordon, who led the league in receiving yards in 2013, struggled after returning in November from his 10-game suspension. He recorded 24 catches for 303 yards and no touchdowns in five games. He initially was given a year-long suspension but his punishment was reduced after the NFL adopted a new drug policy.
Gordon was then suspended by the Browns for their season finale against the Baltimore Ravens for an unspecified violation of team rules.
In 2013, Gordon was suspended for the first two games of the season for violating the NFL's substance-abuse policy. He has missed a total of 13 games due to suspensions during his three-year career.
Gordon, 23, remains under contract with the Browns through the end of the 2015 season. He is due a base salary of $1.068 million. However, because he did not appear in six games, this season will not count toward free agency.