Johnson said he was experiencing severe withdrawal symptoms after he stopped taking an SSRI medication, a type of antidepressant that works by increasing levels of serotonin within the brain. He likened the symptoms to having the flu -- "a lot of nausea, a lot of vomiting" -- except the illness does not go away.
He said he had been dealing with the situation for close to two months, but it worsened during the week leading up to the game against the Kansas City Chiefs on Oct. 3.
"Football wasn't even a question at the time. It was something that I felt even before the season," he said. "I told a few close friends but really kept it bottled up because I felt ashamed of it, I felt like it was a crutch. But coming back, the support I've had from the team, from my friends, from my family, I couldn't ask for nothing better. And getting out here and playing football again, you're reminded of how lucky you are to be in the position that you are in. So, taking it day by day."
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On the day of the Chiefs game, Johnson decided to drive back to his home state of Oklahoma.
"I told my mom and told my dad where I was at [mentally and physically]. It wasn't an enjoyable thing," he said. "A lot was going through my head really for a duration of time. A lot was talked about. ...They were behind me, they were concerned."
Johnson returned to the Philadelphia area that week, but missed three games total while he waited for his symptoms to subside. He returned against the Las Vegas Raiders on Oct. 24 and said he feels "stable" now.
Johnson, 31, said he first started dealing with anxiety in junior college and was officially diagnosed with it when he got to the University of Oklahoma. He has a similar condition to right guard Brandon Brooks, who has missed multiple games over his career as a result of anxiety. The two revealed that they would both vomit before games and talk to one another about it.
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Johnson credits the Eagles coaches, staff and players, especially Brooks, for supporting him.
"The real message is, just don't bottle it up. It's easy to do that," Johnson said. "The bad news is that I think a lot more people have it than what meets the eye. I think it's easy to put on a poker face. ... I remember hearing a stat at the combine that 40-50% of people in the NFL have some sort of condition. [The game] can do a lot of things for you but a lot of times it can be detrimental."