He will miss the first four regular season games of the 2018 season.
"So, I just want to take a few minutes today to share the news with you guys that I received from the NFL," Davis said in a two-minute video on his Twitter page Friday. "I was informed that I tested positive for a banned substance. I was completely caught off guard by this. I've never in any way done anything to try to intentionally cheat the game. It's one of those situations where the NFL rules are clear; they state that you are responsible for what you put in your body. I've taken the same supplements for the last seven or eight years and never had any issues. Been tested numerous times over the years while taking the same stuff. And, unfortunately, these are some of the things that happens when you take supplements.
"I've never tested positive for a steroid or HGH. It's not one of those situations. It ended up being an estrogen blocker that triggered a positive test for me. I just want you guys to know that in no way would I ever do anything, like I said, to cheat this game or to try to create a competitive advantage over anybody. I've always tried to do things the right way and that's something that I'll continue to do when I'm able to get back to the field. I can honestly tell you guys that my conscious is clear in this situation and as bad as it hurts me to sit here and tell you guys this, I know it's going to hurt a lot of people that have looked up and believed in Thomas Davis over the years. Just know, in no way, in no way, have I done anything intentionally to try to cheat this game. I'm going to serve this four-game suspension and I'll be back ready to go back out there with my teammates. And, you know, who knows? Maybe this isn't my last year."
Davis, the 2014 Walter Payton Man of the Year, has started 15 or more games for the Panthers every year since the 2013 season. In his career, he's logged 13 interceptions, 28 sacks and more than 1,000 tackles. He had planned to make the 2018 season his final one, though he said in his Twitter video that could change in light of his four-game ban.