Doan's Pills, a backache remedy that has held a place in America's medicine cabinets for decades, does not live up to its advertising, the government said Wednesday. "If nothing seems to help, try Doan's," ads for the pills have said for years. But when it comes to back pain, the Federal Trade Commission said, Doan's helps no more than products costing half as much. The agency said it even may require Doan's current owner, the $4-billion Swiss pharmaceutical giant Ciba-Geigy Corp., to run "corrective" advertisements. "We categorically disagree with the FTC's ruling and we plan on fighting the issue in court," said Eric Jackson, a Ciba spokesman. "Millions of consumers have chosen this product over the years and those purchasing actions speak volumes." In radio's heyday, Doan's became widely known through incessant advertising, but its history is obscure _ and no one could be found to say whether there even was a Doan who made the pill. The brand was rescued from oblivion in 1981, when the late marketer Martin Richard Himmel licensed it _ along with Ayds appetite suppressants and Cuticura medicated soap _ from the Purex Corp. Martin poured half of his company's revenues back into advertising, and it paid off. In 1986, he sold his company to Dep Corp. for $73-million. Six years later Ciba acquired Doan's from Dep. Ciba declined to give sales figures, but an advertising directory said it spent $5.5-million promoting the pills in one recent year. By a 4-1 vote, the FTC commissioners decided to compel Ciba to back up its advertising claims before an administrative law judge. The case then could take a year to argue. Doan's ads do not directly assert superiority, but imply it, FTC lawyer Joel Winston said. The ads carry such messages as, "If nothing seems to help, try Doan's. It relieves back pain no matter where it hurts. Doan's has an ingredient these pain relievers don't have," or "Back pain is different. Why use these pain relievers? Doan's is just for back pain." "Through these and similar statements," the FTC said, "Ciba claimed that Doan's analgesic products are more effective than other analgesics, including Advil, Aleve, Bayer, Motrin and Tylenol, for relieving back pain." The active ingredient in Doan's is magnesium salicylate, one of a class of chemicals that reduces inflammation. Winston said Doan's price _ $10.29 for 48 pills, compared with $4.37 for 50 Tylenol pills in a Washington drugstore _ amounted to a "price signal" implying the product's superiority. Jordan, McGrath, Case & Taylor Inc., Ciba's advertising agency, which made some of the ads challenged by the FTC, signed a consent agreement promising to stop making those assertions without acknowledging wrongdoing. Corrective ads could be required if the judge found that the ads had been both deceptive and so persistent that they created "false beliefs about a product that would linger on after the advertising ends," the commission said.