“She looked like she had been dragged through a briar bush for several miles,” said Dr. Owen M. Lander, an emergency room doctor at Ruby Memorial Hospital in Morgantown, W.Va.

Bath salts contain manmade chemicals like mephedrone and methylenedioxypyrovalerone, or MDPV, also known as substituted cathinones. Both drugs are related to khat, an organic stimulant found in Arab and East African countries that is illegal in the United States.

They are similar to so-called synthetic marijuana, which has also caused a surge in medical emergencies and been banned in a number of states. In March, the Drug Enforcement Administration used emergency powers to temporarily ban five chemicals used in synthetic marijuana, which is sold in the same types of shops as bath salts.

Shortly afterward, Senator Bob Casey, Democrat of Pennsylvania, asked the agency to enact a similar ban on the chemicals in bath salts. It has not done so, although Gary Boggs, a special agent at D.E.A. headquarters in Washington, said the agency had started looking into whether to make MDPV and mephedrone controlled Schedule I drugs like heroin and ecstasy.

Mr. Casey said in a recent interview that he was frustrated by the lack of a temporary ban. “There has to be some authority that is not being exercised,” he said. “I’m not fully convinced they can’t take action in a way that’s commensurate with the action taken at the state level.”

Senator Charles E. Schumer, Democrat of New York, introduced federal legislation in February to classify bath salts as controlled Schedule I substances, but it remains in committee. Meanwhile, the drugs remain widely available on the Internet, and experts say the state bans can be thwarted by chemists who need change only one molecule in salts to make them legal again.

And while some states with bans have seen fewer episodes involving bath salts, others where they remain fully legal, like Arizona, are starting to see a surge of cases.