TL;DR
Antibiotics can disrupt the gut microbiome, which may increase the risk of asthma by altering immune development. Modern human studies show that repeated or early-life antibiotic exposure is associated with a higher likelihood of asthma later on. Supporting the microbiome—through diet, lifestyle, and careful use of antibiotics—may help maintain healthier immune responses.
Early Animal Study Linking Antibiotic Use to Changes in Bowel Flora
Researchers from the University of Michigan Medical School found that, in mice, antibiotics may be responsible for changing the makeup of the bowel flora. A change in bowel flora could affect the way the immune system responds to common allergens in the lungs. According to one of the researchers, antibiotics eliminate bacteria in the GI tract. The destruction of the normal bacteria enabled fungi to take control.
In earlier experiments, researchers have found that fungi produce oxylipins. Oxylipins are molecules that are associated with the level of immune responses. Oxylipins in the GI tract help prevent the production of regulatory T cells (a type of white blood cell) for ingested allergens. The result is that T cells in the respiratory system can become sensitive to allergens, leading to allergy symptoms and, in some cases, asthma.
The University of Michigan researchers tested this idea on mice. The mice were given Candida albicans (a yeast) orally after being given antibiotics for five days. The Candida served to inoculate the GI tract with yeast—in other words, change the makeup of the intestinal flora. Another group of mice received no antibiotics or oral Candida albicans. The mice were then injected with common mold spores. The mice that were given antibiotics and exposed to C. albicans displayed higher rates of hypersensitivity to mold, as opposed to the mice that weren’t given any antibiotics.
Newer Research Links Antibiotic Use to Allergies and Asthma
2019: A retrospective chart review of data found that the administration of antibiotics within the first 12 months of life was significantly associated with lifetime asthma [1].
2020: A review of 100 studies found that antibiotic exposure prenatally and during the first 2 years of life significantly impacts the risk of developing atopic and metabolic disorders. Exposure during the first 6 months of life appears most critical, consistent with this being the time when the microbiome is most vunerable [2].
2022: In a meta-analysis of 18 studies, the authors stated, “In conclusion, this meta-analysis suggests that antibiotics in early life might be associated with allergic rhinitis. Even though antibiotics can be necessary for early life, these results highlight that the use of antibiotics in infants should be carefully weighed to avoid the inappropriate use of antibiotics and cause health issues in later life.” [3]
2023: By linking prescription records with a large Australian study following children from birth to age 15, researchers were able to track asthma over time and see whether taking antibiotics early in life was connected to different asthma patterns, even after adjusting for other factors [4].
2023 (antibiotic use in adults): Researchers analyzed data from nearly 249,000 adults aged 40+ in Korea’s NHIS health screening program. They reviewed each person’s antibiotic use over five years and then tracked new asthma cases from 2007–2019. In total, 42,452 people developed asthma. Statistical models were used to determine whether higher antibiotic use increased asthma risk. Subjects using antibiotics for more than 90 days were more likely to develop asthma as an adult [5].
FAQ
Does taking antibiotics increase asthma risk?
Recent large-scale human studies suggest that repeated or early-life antibiotic exposure is associated with a higher likelihood of developing asthma. The proposed mechanism involves disruption of gut flora, which plays a key role in immune development.
Why would gut bacteria affect the lungs?
The gut and lungs communicate through the “gut–lung axis.” When gut flora is disrupted, it can change immune signaling and increase sensitivity to allergens that affect the lungs.
Are all antibiotics equally risky?
Evidence shows the risk appears to increase with total exposure (more courses and more antibiotic classes). No single antibiotic has been identified as the only driver.
Does taking probiotics with antibiotics help?
Some research suggests probiotics may help preserve microbial balance, but results are mixed.
Does this mean people should avoid antibiotics?
Not at all. Antibiotics are important when clearly needed. The issue is unnecessary or repeated use, especially in children.
Can adults develop asthma after antibiotic use?
Yes. Newer research shows that even adults with significant antibiotic exposure may have a higher risk of later asthma diagnoses, although the link is stronger in children.
What can support a healthy microbiome?
A diverse, whole-food diet rich in fiber, limiting unnecessary antibiotics, spending time outdoors, and avoiding excessive sanitizing all contribute to microbial diversity.
References:
- BMC Pediatr. 2019 Jul 5;19:225. doi: 10.1186/s12887-019-1594-4 Early antibiotic exposure and development of asthma and allergic rhinitis in childhood
- Evol Med Public Health. 2020 Oct 24;2020(1):279–289. doi: 10.1093/emph/eoaa039 The impact of early life antibiotic use on atopic and metabolic disorders
- Open Med (Wars). 2022 Nov 4;17(1):1760–1772. doi: 10.1515/med-2022-0459 Meta-analysis of early-life antibiotic use and allergic rhinitis
- Antibiotics (Basel). 2023 Feb 3;12(2):314. doi: 10.3390/antibiotics12020314 Early-Life Antibiotic Exposure and Childhood Asthma Trajectories: A National Population-Based Birth Cohort
- BMJ Open Respir Res. 2023 Nov 1;10(1):e001643. doi: 10.1136/bmjresp-2023-001643 Association between antibiotics and asthma risk among adults aged over 40 years: a nationally representative retrospective cohort study
