OWINGS MILLS, Md. — Baltimore Ravens quarterback Lamar Jackson is sidelined again with an illness.

The reigning NFL Most Valuable Player didn’t practice Friday after returning briefly Wednesday.

“He’s fighting through an illness, working with our doctors and doing even more tests to make sure we got everything covered,” Ravens coach John Harbaugh said after Friday’s practice. “I’m confident he’ll be back pretty soon. It’s just an unpredictable deal. You guys have been sick before. Sometimes it’s not easy. That’s what we’re dealing with.”

Jackson made his camp debut Wednesday but left an hour into practice. He didn’t look like himself, completing one pass in team drills and throwing one interception before exiting midway through practice. Jackson looked weary in walking off the field Wednesday.

“He was just not feeling up to it in terms of all the different things,” Harbaugh said. “You got hydration, and there’s an energy-level thing. It’s part of being sick.”

The Ravens had an off day Thursday before holding their first padded practice of camp Friday. Josh Johnson, Baltimore’s 38-year-old backup, ran the first-team offense.

Jackson has now missed four of the first five practices in training camp. This has been a recurring issue for Jackson, who has missed at least one practice due to illness in each of his first seven NFL seasons.

“It is what it is,” Pro Bowl center Tyler Linderbaum said. “You never know throughout the course of a season what is going to happen. It’s always good to get work in with other people.”

Linderbaum then added with a smile, “But we’ll be excited when Lamar is back. That’s for sure.”