He was admitted Monday, after turning up ill Sunday at the team's training camp. Patten suffered vomiting and severe headaches and was isolated from teammates, The Washington Post reported.
The eight-year veteran -- who was undrafted out of Western Carolina and spent most of his career with New England -- missed much of the 2005 season because of injury.
The hospitalization does not bode well for his future with the club. When he did play, he had 22 catches for 217 yards and no touchdowns.
Patten signed with the Redskins as a free agent last off-season.
In his career, he has 258 receptions for 3,736 yards and 20 touchdowns.