"I've had two separate illnesses," Ziegler said before Sunday's game against Toronto. "I had the flu. That took away my strength and zapped my energy a little bit. This week, I had an asthma attack Tuesday night, and I've had major lung trouble all week and been coughing real bad. So that's been the biggest thing I've been dealing with."
Ziegler said team doctors believe the flu probably triggered the asthma attack.
"I'm still probably two weeks away from being 100 percent," Ziegler said. "I'm to the point now where I feel like I can pitch in the game and be effective. I think they'll have me in there the first chance they get."
Ziegler returned to action from the flu on Tuesday, throwing a scoreless inning against the Angels. On Thursday, though, he gave up four hits and a career-high three runs in one-third of an inning against Texas. That ended his six-game, 8 1/3-inning scoreless streak.
Ziegler, who's listed at 6-foot-4 and 205 pounds, said he lost about eight pounds because of the flu. He hasn't even stepped on the scale the past few days.
"I know I'm not where I was before," Ziegler said. "When I know that I feel better, I'll check it and see where I'm at."
Eric Gilmore is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.