Is this what your doctor looks like?

Harmful reactions to some of the most widely used medicines — from insulin to a common antibiotic — sent more than 700,000 Americans to emergency rooms each year, landmark government research shows.

Accidental overdoses and allergic reactions to prescription drugs were the most frequent cause of serious illnesses, according to the study, the first to reveal the nationwide scope of the problem. People over 65 faced the greatest risks.

“This is an important study because it reinforces the really substantial risks that there are in everyday use of drugs,” said patient safety specialist Bruce Lambert, a professor at the University of Illinois at Chicago’s college of pharmacy.

Even so, the study authors and other experts agreed that the 700,000 estimate was conservative because bad drug reactions are likely often misdiagnosed.

The study found that a small group of pharmaceutical warhorses were most commonly implicated, including insulin for diabetes; warfarin for clotting problems; and amoxicillin, a penicillin-like antibiotic used for all kinds of infections.

“These are old drugs which are known to be extremely effective. We could not and would not want to live without them. But you’ve got to get the dose exactly right. Variations, especially on the high side, are really dangerous,” Lambert said. He was not involved in the research.

Complications included diabetics on insulin passing out from low-blood sugar, excessive bleeding in patients on warfarin, and severe skin rashes in patients taking amoxicillin. Drug reactions were severe enough to require hospitalization in about 17 percent of patients. The study did not include information on whether any of the reactions were fatal.

Listening to the side effects roster during pharmco commercials is scary enough to keep half the Web in business with folks checking out what-the-hell their doctor really has prescribed for them.