Early antibiotic use in childhood appears to carry a measurable risk for later respiratory and allergic outcomes. In this study, which included 1,401 US children, antibiotic exposure during the first six months of life was highly associated with a 1.5 times greater chance of asthma by age six, as well as having similarly increased odds for developing allergies. The authors specifically found that this association persisted even among children without early lower‐respiratory tract infections and among those whose asthma onset occurred after age three, which reduces the likelihood that the association is simply reverse causation. An example of this error would be the early onset of asthma (wheezing) being treated with antibiotics after the fact.
The study centers on this early window (first six months) and suggests that antibiotic exposure during this period of immune system development may disrupt the normal development of the microbiome, impairing the development of immune tolerance and thereby increasing the risk of allergies or asthma later in life. Microbiome studies indicate that broader-spectrum agents may have greater disruptive potential. These findings underscore that when antibiotics are considered for use in very young infants, especially multiple courses or broad-spectrum agents, health care professionals and parents should weigh the risk of long-term immune system function risk alongside the immediate need for treatment. Further studies have suggested that broad-spectrum antibiotics, particularly macrolides and cephalosporins, are most strongly associated with increased asthma and allergy risk. These classes are thought to have greater disruptive effects on gut microbial diversity, which may explain their stronger link to immune-related outcomes.
Early antibiotic exposure is also linked to higher risks of several childhood gastrointestinal disorders, such as inflammatory bowel disease (IBD), and some studies indicate celiac diseases and functional disorders such as IBS as well. This review found that exposures in the first years of life were associated with later IBD diagnoses, with some studies indicating that more courses of antibiotics increase the risk proportionally. Associations for celiac disease and IBS tended to follow the same pattern, especially when antibiotics were given early in life. The authors emphasize that the strongest signal appears when antibiotics are given during the important microbiome development period discussed earlier. The review concludes that early-life antibiotic use may increase later GI disease risk and that, as stated before, medical professionals and parents should exercise caution when giving their young children antibiotic treatments.
Regarding antibiotic types and mechanisms, the review highlights that broad-spectrum agents (those that substantially disturb microbial diversity) are most often implicated in the appearance of these conditions, whereas more narrow-spectrum agents (such as penicillin) do not show a consistent link. The proposed mechanism is microbiome disruption during the previously mentioned critical developmental window, leading to long-term changes in immune regulation and gut barrier function that can predispose to immune-mediated gut disease. It is important to note the limitations of the source studies, as they are mostly observational and may not account for other factors, such as “confounding by indication”. This means that the infections that prompt the use of antibiotics in infants and young children may also themselves increase the chance of disease later in life. In summary, early and repeated broad-spectrum antibiotic exposure is associated with increased risk of later GI disorders, but more studies would need to be conducted to rule out other possibilities
In the United States, a significant proportion of outpatient antibiotic prescriptions for children are unnecessary, particularly for conditions resulting from viral infections. It is estimated that about 90% of otitis media/bronchitis cases are caused by viral infections. The Centers for Disease Control and Prevention (CDC) also estimates that at least 60% of the time, antibiotics are prescribed for these infections. To reduce inappropriate antibiotic prescriptions for viral infections in children, the CDC has implemented outpatient programs that provide guidance on when it is wise to prescribe antibiotics to children. These programs include education, support tools, and feedback systems that track prescribing patterns and encourage adherence to CDC guidelines. Public awareness campaigns also aim to educate parents and caregivers about when antibiotics are necessary, which may act as a second barrier between providers who are financially incentivized to prescribe drugs and the children who take them.
The research described above does indicate that inappropriate antibiotic prescriptions for viral infections in early childhood likely contribute to the problems described above. All of this indicates that unnecessary antibiotic use can disrupt the developing gut and airway microbiomes during crucial periods of immune system development, which is linked to increased risks of asthma, allergies, and GI disorders like IBD or IBS. Broad-spectrum antibiotics seem to cause the greatest disruption to normal development by reducing overall microbial diversity, which may change immune regulation long-term. While observational studies cannot stand on their own to provide a definitive link, the consistency of associations across multiple studies suggests that unnecessary and/or prolonged antibiotic exposure is a significant risk factor. Reducing these prescriptions should be done, not only because it limits immediate side effects and resistance, but may also help prevent chronic immune-mediated conditions that arise later in childhood or adult life.
Microbiology 251 Blog 