E! News reports that the comedian recently cancelled all of his stand-up tour appearances and has been missing from his slot on Howard Stern's radio show.
In a statement, Lange's spokesperson said: "We can confirm that Artie is in the hospital. Artie has chosen to keep all information on this matter between him and his doctor. There will be no further comment."
Lange, who has reportedly struggled with substance abuse in the past, pleaded guilty to driving under the influence in October.