Henderson reportedly fell foul of the NFL's drug policy after using medicinal marijuana to ease discomfort from Crohn's disease.
Henderson, 24, reportedly fell foul of the NFL's drug policy after using medicinal marijuana to ease discomfort from Crohn's disease, an inflammatory condition which affects the bowel.
Henderson had already served a four-game suspension at the start of the season. His latest ban "begins immediately," the NFL said in a statement.
Henderson said in an interview last month he was only using marijuana because it had been recommended by his doctors to help ease pain from the disease and two separate intestinal surgeries.
"I've got doctors telling me this is the No. 1 medicine that would help your disease," Henderson told the Buffalo News last month.
"You try to tell that to the league, and it seems like they didn't care too much."
Henderson's ban comes amid growing calls for the NFL to relax its rules on marijuana.
Both Tennessee Titans linebacker Derrick Morgan and former Baltimore Ravens tackle Eugene Monroe have called for the NFL to allow medical marijuana use.
"I feel like the NFL has a responsibility to look into it, to delegate time and money to research this for its players," Morgan said earlier this year.
NFL Commissioner Roger Goodell has said there are no plans to relax the marijuana ban, defending it as being "in the best interest of our players and the long-term health of our players."