One in five elderly Americans has had an adverse reaction to a prescription drug, from nausea to serious breathing difficulties, a study indicates.

Two of five people who claimed an adverse reaction said it was serious or very serious, said gerontologist Beverly Lowe of the University of Southern California.Lowe was principal researcher in the survey of 1,002 men and women over 60. The survey was part of a project examining the usefulness of various services offering information about prescription drugs to the elderly.

About 87 percent of the respondents said they relied on their doctor for such information. But only 28 percent said their doctor told them which foods to avoid when taking the drug, and only 29 percent said they were advised of side effects.

Eight percent said they were given no information about prescription drugs they took daily.

Thirty-six percent said they received information about their prescriptions from a pharmacist; 30 percent said they read leaflets enclosed with the drugs.