"As a professional, you're supposed to be aware of what you put in your body and take precautions," Johnson said. "That's something I didn't do, and now I pay the price."
Johnson was evasive about which prescription drug he took, and what condition it was prescribed for. Johnson said he met with Kelly on Friday morning, and Kelly did not want him to offer details. But that invites skepticism about the source of the failed test, as many players busted for PEDs have prescription drugs as an alibi. Johnson understood that a seven-pound weight increase also raised eyebrows.
"People's opinion, it's nothing I can stop or prevent," Johnson said. "It's ultimately my mistake, something I brought on myself and I got to deal with. Let my teammates down, Chip down, and Howie, everyone in the Eagles organization."
Johnson later tweeted the following: "To clarify my interview - I wanted to keep the details of my medical condition private. Chip simply supported me in MY decision."
The mistake Johnson confessed to was not checking with Eagles trainer Chris Peduzzi. Veterans on the Eagles said that is what players are taught to do, and Kelly told Johnson on Friday that the team has resources to help a player avoid this result.
Johnson became the second Eagles player suspended for PEDs this offseason. Second-year linebacker Jake Knott was the other. The Eagles had only one drug suspension in coach Andy Reid's 14 years in Philadelphia. Johnson did not think the Eagles' oversight was lacking, and linebacker Connor Barwin said inexperience contributed to the poor decisions.
"An older guy wouldn't make that mistake," Barwin said. "Any doctor you see, whether it's a foot doctor or dermatologist, you just use an Eagles doctor. And I think the young guys have learned that and definitely won't make that mistake again."
Johnson said the team facility has a list of more than 100 substances not to take. He took the drug away from the facility. Guard Evan Mathis, who has trained with Johnson, said it's "not a good situation" and conceded that Johnson was not smart to take the prescription drug.
"It's not like he was taking something for an extended period of time," Mathis said. "He got caught in a small window doing it, thinking he could take it OK because he had a prescription. And if he went through the proper channels, he wouldn't have done that."
Johnson said the toughest part of the suspension is that he cannot be around the team during the four-week absence. So he must find a place to train and someone with whom he can do one-on-one offensive-line drills.
The No. 4 overall pick in the 2013 draft, Johnson started all 16 games last season. He was encouraged by the way he played toward the end of the season and in minicamps, generating optimism about his second season. It will be more difficult to pick up at a high level in Week 5.
Allen Barbre, who is expected to replace Johnson, received a three-year contract extension a few weeks after management learned of Johnson's suspension.
Johnson would not compare his four-week suspension to Ray Rice's two-week ban in an assault case. He said he's in a situation similar to that of other players who have failed drug tests, and he faces a similar consequence.
"It's all my fault," Johnson said. "I have no one to blame but me."