WASHINGTON — The Obama administration said on Tuesday that it would ask Congress to spend an additional $1.1 billion next year to combat a growing epidemic of prescription painkiller and heroin abuse.

Almost half of the new money would be used to expand treatment facilities, which are in short supply in much of the nation.

“Opioid abuse and overdoses have hurt families from across this nation,” Sylvia Mathews Burwell, the secretary of health and human services, said in a news conference. “My home state of West Virginia has felt the cost almost more than any other.”