Coleman's agent, Robert Malcolm, says the 41-year-old actor was doing promotional work at a hotel Wednesday morning and went to his room to rest.
Malcolm says Coleman then began feeling unwell, although he doesn't have any details.
The Los Angeles Fire Department says an ambulance was sent to the hotel shortly after 8 a.m.
Malcolm says Coleman was taken to a hospital for tests. He says the actor is doing well but he doesn't know when Coleman will be released.
Coleman played Arnold Jackson on the popular 1980s sitcom "Diff'rent Strokes."
He's had two kidney transplants.