Falwell, 71, was taken Sunday to Lynchburg General Hospital after falling ill at a church service. He had battled a severe cold last week and saw a doctor Friday.
"It's not considered dangerous," said Falwell, a television evangelist and chancellor of Liberty University in Lynchburg. "It is just troublesome. I am going to be here a few days."
Falwell said doctors planned to keep him at the hospital "until my lungs clear."
Falwell, a Christian fundamentalist minister, is best known for his political activism.
In 1979, he founded the Moral Majority - a group focused, in his words, on mobilizing "religious conservatives around a pro-life, pro-family, strong national defense and pro-Israel platform, designed to return America to her Judeo-Christian heritage."
Falwell led the group for ten years before moving on to other projects but last year returned to the political battlefield, establishing the Moral Majority Coalition, whose purpose is described as using "the momentum of the November 2 elections to maintain an evangelical revolution of voters who will continue to go to the polls to "vote Christian."
On board with Falwell for the new Moral Majority are his son, Jonathan Falwell, as executive director, and Tim LaHaye, the fundamentalist author of the "Left Behind" novels which weave fictional stories around Biblical scenarios of the end of the world.