The ex-MadTV comedian is suffering from an as-yet-unknown ailment, his camp told E! Online.
"We can confirm that Artie is in the hospital," Lange's rep said. "Artie has chosen to keep all information on this matter between him and his doctor.
There will be no further comment," the rep said.
Lange, 42, has dealt with health problems including substance abuse in the past. He was also busted in 2009 for a DUI, under the influence of prescription sleeping pills.
The comedian has been absent from his gig on Howard Stern's Sirius show for the past month and has canceled his stand-up tour until February, his Web site said.