WASHINGTON — Taxpayers have shelled out at least $200 million since 2004 for medications that have never been reviewed by the government for safety and effectiveness but are still covered under Medicaid, an Associated Press analysis of federal data has found. Millions of private patients are taking such drugs, as well.

The availability of unapproved prescription drugs to the public may create a dangerous false sense of security. Dozens of deaths have been linked to them.

The medications date back decades, before the Food and Drug Administration tightened its review of drugs in the early 1960s. The FDA says it is trying to squeeze them from the market, but conflicting federal laws allow the Medicaid health program for low-income people to pay for them.

The AP analysis found that Medicaid paid nearly $198 million from 2004 to 2007 for more than 100 unapproved drugs, mostly for common conditions such as colds and pain. Data for 2008 were not available but unapproved drugs still are being sold. The AP checked the medications against FDA databases, using agency guidelines to determine if they were unapproved. The FDA says there may be thousands of such drugs on the market.

Medicaid officials acknowledge the problem, but say they need help from Congress to fix it. The FDA and Medicaid are part of the Health and Human Services Department, but the FDA has yet to compile a master list of unapproved drugs, and Medicaid — which may be the biggest purchaser — keeps paying.

"I think this is something we ought to look at very hard, and we ought to fix it," said Medicaid chief Herb Kuhn. "It raises a whole set of questions, not only in terms of safety, but in the efficiency of the program — to make sure we are getting the right set of services for beneficiaries."

At a time when families, businesses and government are struggling with health care costs and 46 million people are uninsured, payments for questionable medications amount to an unplugged leak in the system.

Sen. Charles Grassley, R-Iowa, has asked the HHS inspector general to investigate.

That unapproved prescription drugs can be sold in the United States surprises even doctors and pharmacists. But the FDA estimates they account for 2 percent of all prescriptions filled by U.S. pharmacies, about 72 million scripts a year. Private insurance plans also cover them.

The roots of the problem go back in time, tangled in layers of legalese.

It wasn't until 1962 that Congress ordered the FDA to review all new medications for effectiveness. Thousands of drugs already on the market were also supposed to be evaluated. But some manufacturers claimed their medications were "grandfathered" under earlier laws, and even under the 1962 bill.