Reid did not show up for his normal Monday media availability, but is expected to rejoin the team later Monday or Tuesday.
Reid left Arrowhead Stadium in an ambulance after Sunday's loss to the Los Angeles Chargers. The Chiefs announced Sunday evening that Reid "fell ill" at the game's conclusion and was in stable condition at a local hospital. The team didn't expound on what type of illness Reid suffered.
Reid, 63, coached the entirety of Sunday's game and didn't show any outward signs of illness. Players were surprised to hear that he wasn't well, according to NFL Network's James Palmer, who reported that Reid's absence at Sunday's postgame media conference was due to "caution."
Defensive coordinator Steve Spagnuolo addressed reporters in Reid's absence Monday.
"The most important thing is coach Reid, so we're glad that he's feeling better," Spagnuolo said.