WASHINGTON (Reuters) -
Bad reactions to antibiotics, mostly
allergic ones, send people to U.S. emergency rooms more than
140,000 times each year, government researchers reported on
Wednesday.

The findings offer another reason for doctors to limit
their use of the drugs, which are overused in the United
States, the team at the U.S. Centers for Disease Control and
Prevention said.

“This number is an important reminder for physicians and
patients that antibiotics can have serious side effects and
should only be taken when necessary,” said the CDC's Dr. Daniel
Budnitz, who led the study.

For the first report ever done on adverse reactions to
antibiotics in the United States, the researchers used the
National Electronic Injury Surveillance System-Cooperative
Adverse Drug Event Surveillance project, a sample of 63 U.S.
hospitals, between 2004 and 2006.

They found more than 6,600 emergency visits were due to an
adverse reaction to an antibiotic. They used formulas to
extrapolate this to the whole country and estimated that
142,000 such emergency visits are made every year.

“Systemic antibiotics (pills or injections as opposed to
creams) were implicated in 19.3 percent of all emergency
department visits for drug-related adverse events,” they wrote
in the September 15 issue of Clinical Infectious Diseases.

Penicillin and related antibiotics such as amoxicillin,
widely prescribed and widely seen as safe, accounted for half
the emergency visits. Other classes of antibiotics such as
cephalosporins, fluoroquinolones and newer antibiotics
accounted for the rest.

“Persons aged 15-44 years accounted for an estimated 41.2
percent of ED visits. Infants accounted for only an estimated
6.3 percent of ED visits,” they wrote.

Budnitz and colleagues said 78 percent of the adverse
events in the study were allergic reactions, ranging from rash
to a serious reaction known as anaphylaxis, and the remaining
22 percent were caused by errors and overdoses.

Many studies have suggested that half of the estimated 100
million antibiotic prescriptions written for respiratory tract
infections in the United States are unnecessary. Most such
infections are caused by viruses, and antibiotics are useless
against them.

But, Budnitz and colleagues said, doctors still often
believe their patients are exceptions to the rule and continue
to write the prescriptions.

“Because antibiotics are frequently used, both
appropriately and inappropriately, if doctors would reduce the
number of antibiotics they prescribe to their patients by even
a small percentage, we could significantly reduce the number of
emergency visits for antibiotic adverse events,” Budnitz said
in a statement.

“Antibiotics are among the most frequently used medications
in the United States. Annually, antibiotics are prescribed to
an estimated 16 percent of patients during ambulatory care
visits, and pharmaceutical manufacturers spend $1 billion
promoting antibiotics,” Budnitz wrote.

(Reporting by Maggie Fox, editing by Will Dunham and Vicki
Allen)