WEDNESDAY, Oct. 1, 2003 (HealthDayNews) -- Doctors already know excessive use of antibiotics in children is a bad idea. Now there's another reason to prescribe with caution: Researchers have linked antibiotic prescriptions in infancy to the development of allergies and asthma later in life.
While it's not clear whether consumption of the bacteria fighters directly causes allergies, experts are almost certain there's a connection. Babies who got antibiotics were at especially high risk for allergy problems if they lived in homes without at least two pets or had a family history of allergies.
But experts cautioned against antibiotic phobia. "This doesn't mean don't give your children antibiotics," says Dr. Stanley Goldstein, a fellow of the American Academy of Allergy, Asthma and Immunology.
According to Goldstein, an estimated 20 percent to 25 percent of American children suffer from allergies, while 5 percent to 7 percent have asthma. Both allergies and asthma are signs the body's immune system is overreacting to foreign invaders.
Over the past couple of decades, researchers have developed a theory that human immune systems are more likely to develop properly if exposed to germs and pet dander at a young age. "We now grow up in a more sterile environment," Goldstein says. "We're not stimulating that immune system with bacteria, and there's a higher incidence of allergies."
In Europe, research has shown that East Germans, who lived in a more rural environment than their counterparts to the West, actually developed a higher rate of allergies after living standards rose in the wake of the unification of the two countries, Goldstein says.
Antibiotic use in infants, meanwhile, may contribute to allergies by killing off bacteria in the intestine that appears to play a role in the development of a healthy immune system, Goldstein says.
In the new study, researchers examined an earlier research project that followed 448 Michigan-area children from infancy to the age of about 7 in the late 1980s and early 1990s. At the older age, the children all had allergy testing.
The results of the study were released Sept. 30 at a conference of the European Respiratory Society in Vienna.
The researchers, from the Henry Ford Health System, found that about 38 percent of the older children showed signs of allergies to pets, ragweed, grass and dust mites and 5 percent had asthma. Those children who had taken antibiotics in the first six months of life -- almost half of those surveyed -- were 1.5 times more likely to develop allergies and 2.5 times more likely to develop asthma.
The allergy rates rose even higher for children given antibiotics who didn't live in houses with at least two pets (cats or dogs), who had a mother with a history of allergies, and who were breast-fed for more than four months.
Researchers don't know why the children took antibiotics as infants. "We didn't look at whether they were prescribed appropriately or inappropriately," says study researcher Dr. Keoki Williams, a clinical epidemiologist at Henry Ford Health System.
Worries about the overuse of antibiotics, which appears to strengthen some bacterial disease, have risen in recent years. During the years of the study, however, the risk wasn't as well known as it is now.
In light of the new research, "there's now potentially more than one reason to use antibiotics judiciously in young children," Williams says.
To learn more about allergies and asthma, visit the American Academy of Allergy, Asthma and Immunology or the National Institute of Allergy and Infectious Diseases.