The US Food and Drug Administration does a poor job of monitoring drug companies’ promotion of unapproved or “off-label” uses of their drugs, says a report by the US Government Accountability Office, the investigative arm of Congress.

Charles Grassley, an Iowa senator who is the senior Republican member of the Senate Committee on Finance, asked the accountability office to review the FDA’s effectiveness in monitoring drug companies’ efforts to promote off-label uses. He said he was concerned about the possible effects of such promotion on doctors’ prescribing practices and on patients’ safety.

Although doctors may prescribe drugs off label for indications that have not been approved by the FDA, drug companies are forbidden from promoting such unapproved uses.

The accountability office’s report said the FDA’s …