Colon, who began the 2012 season with the Oakland A's, is in the middle of serving a 50-game suspension for violating MLB's banned substances policy after testing positive for heightened levels of testosterone back in August.
The former Cy Young winner was making his second start for Aguilas Cibaenas in the Dominican Winter League on Sunday when a line drive hit him square in the mouth, according to ESPN Radio's Carlos Almanzar.
It was a scary moment, but Colon walked off the field and was taken to a hospital to undergo further tests.
On Monday, Colon's agent said the player was doing well, the San Jose Mercury News reports.
"He took a ball off the chin and needed some stitches, but he's fine," agent Adam Katz said.
The incident is the latest example of how vulnerable pitchers are to line drives. Last Thursday, Detroit Tigers starter Doug Fister continued to pitch after getting hit in the head by a comebacker in Game 2 of the World Series, Bleacher Report notes.
The league is looking for ways to better protect pitchers. Officials are considering using protective cap liners made of Kevlar, "the high-impact material used by military, law enforcement and NFL players for body armor," the Associated Press reports.