Early Antibiotics May Raise
Studies Suggest Risk Is Double for
March 13, 2006 -- Babies treated with even one course of antibiotics during
their first year of life may have twice the risk of developing asthma later
in childhood as unexposed babies, an analysis of past research shows.
The findings bolster the theory that an increase in the use of antibiotics
early in life may be a factor in the epidemic rise in childhood asthma. They
also suggest that greater exposure to antibiotics is associated with greater
Approximately one in eight children in the U.S. has asthma, and asthma rates
among children under age 5 have increased especially between 1980 and the
mid-1990s, according to figures from the CDC.
While results from the pooled studies point to a link between early
antibiotic exposure and asthma, they fall short of proving the association,
says Carlo A. Marra, PhD, PharmD, of the University of British Columbia.
"Antibiotic exposure during the first year of life does appear to be a risk
factor for the development of childhood asthma, but because of limitations
in the studies we reviewed we have to conclude that bigger and better
studies are still needed," he tells WebMD.
Different Studies, Different Findings
The association between early antibiotic use and childhood asthma was
significantly stronger in studies that relied on parent recall than in those
that followed children over time.
Marra says the recall, or retrospective, studies may have been compromised
by bias. Specifically, the parents of the children with asthma may have been
more likely to report early antibiotic exposures than parents of children
An analysis of five studies that examined the effect of treating infants
with multiple courses of antibiotics showed that greater exposure to the
drugs was associated with greater asthma risk. But this association was
again seen in the retrospective studies.
The study is published in the March issue of the journal Chest
While not conclusive, Marra says the findings offer some of the strongest
supporting evidence yet in favor of the so-called 'hygiene hypothesis,'
which suggests that increasingly sterile environments may be making children
more susceptible to allergies and asthma.
Early use of antibiotics has been implicated because the drugs kill good
bacteria in the gut, which may, in turn, weaken the immune system.
Allergist Clifford W. Bassett, MD, FAAAAI, says the analysis illustrates the
potential importance of early environmental exposures in future health.
He adds that it is up to pediatricians and other doctors who treat babies
and children to educate parents about when antibiotics are beneficial and
when they are not.
Traditional antibiotics are useful for the treatment of bacterial infections
but are of no use in the treatment of viral infections such as colds and
Bassett is with The Long Island College Hospital in Brooklyn, N.Y. He is
also vice chairman of the public education committee of the American Academy
of Allergy, Asthma, and Immunology.
"Clearly, you wouldn't want to withhold an antibiotic when it is needed
because of a theoretical risk of asthma," he says. "But this research does
underscore the importance of not overusing these drugs, especially early in
SOURCES: Marra, F. Chest, March 2006; vol 129: pp 610-618. Carlo A.
Marra, PharmD, PhD, assistant professor of pharmaceutical sciences,
University of British Columbia, Vancouver. CDC Surveillance for Asthma,
Morbidity and Mortality Weekly Report, 1998; vol 47 (SS-1). Summary
Health Statistics for US Children, 2004, NCHS, CDC. Clifford W. Bassett, MD,
FAAAAI, allergist, The Long Island College Hospital, Brooklyn, N.Y.; vice
chairman for public education, American Academy of Allergy, Asthma, and