Denver Broncos cornerback Tracy Porter has been held out from football activities because of seizure concerns.

Porter suffered a seizure in August, then experienced the same symptoms -- light-headedness and a racing heart -- before the Broncos flew to face the San Diego Chargers in Week 6.

"I had never had one before, 26 years I've been living," Porter told The Denver Post on Thursday. "Before the San Diego game, I don't know if it was the medication I was taking or it was a setback, but they decided to hold me back."

Porter returned to practice this week, but he still hasn't been cleared to play. He was limited Wednesday and missed Thursday's practice because of a doctor's appointment.

"Right now, Tracy is being evaluated," Broncos coach John Fox said. "When he's cleared to physically be able to practice, he'll be out there. I don't know all the symptoms. When we figure out how to deal with the illness, then he'll be out here."

Porter also tweeted: "I would like to thank EVERYONE for the prayers and wishes. It really means a lot to me."

Fox didn't sound optimistic about Porter's chances for Sunday's game against the New Orleans Saints. And the one thing the Broncos need against the Saints: healthy cornerbacks.