Otitis media, antibiotics, and risk of autism spectrum disorder.
Huge Danish cohort shows only a small, likely non-causal uptick in autism after ear infections or antibiotics.
01Research in Context
What this study did
Wimberley et al. (2018) tracked every child born in Denmark for up to 15 years. They asked: do kids who get ear infections or take antibiotics early in life get an autism diagnosis more often?
The team used national registries. They counted 780,547 children. They noted who had otitis media and who filled antibiotic prescriptions. Then they watched who later got an ASD diagnosis.
What they found
Kids with ear infections or antibiotic use had a slightly higher chance of later autism. The increase was tiny in real numbers. There was no extra risk when both factors happened together.
The authors warn: other reasons, not the drugs or infections, could explain the link. They say do not jump to causal claims.
How this fits with other research
Yanai et al. (2025) used the same registry style and also saw a small rise in ASD after serious brain infections. Together, the two papers show that many early medical events, not just ear problems, show the same weak signal.
Bottema-Beutel et al. (2015) found kids with autism are twice as likely to have food allergies. This shifts focus from cause to comorbidity: once autism is present, immune issues keep piling up.
Njardvik et al. (1999) showed hearing loss is common in autistic children. Theresa’s ear-infection data fit this picture: ear trouble and autism travel together, but we still do not know which comes first.
Why it matters
You will meet kids with repeated ear infections. This study says you do not need to fear antibiotics as an autism trigger. Keep treating infections as usual. Do keep an eye on hearing status, because Njardvik et al. (1999) reminds us one in five autistic clients may have undetected loss. When parents worry about past antibiotics, share the real numbers: the risk increase is tiny and probably not causal.
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02At a glance
03Original abstract
Otitis media infections and antibiotic treatment have been linked to the risk of developing autism spectrum disorder. Broad-spectrum antibiotics may alter the composition of the gut flora microbiota, which is hypothesized to be involved in the regulation of the immune system. This study examines the interplay among otitis media, antibiotics, and the subsequent risk of developing autism. Based on the entire Danish population, 780,547 children were followed from birth (January 1, 1997 to December 31, 2008) until December 31, 2012. We calculated adjusted hazard ratios and absolute risks of autism with 95% confidence intervals (CIs) related to previous otitis media diagnoses and antibiotic prescriptions redeemed at Danish pharmacies. The absolute risk of autism before age 10 was increased among children with otitis media (1.2% for females and 3.3% for males) and in children who had redeemed an antibiotic prescription (0.6% and 2.7% for females and males) compared to children without a history of otitis media and antibiotics usage (0.4% for females and 1.9% for males). Similarly, we found an increased hazard ratio of autism associated with otitis media (1.83 95% CI 1.71-1.95) and antibiotics usage (1.29 95% CI 1.17-1.43). A history of both otitis media and antibiotic treatment did not further increase the risk of autism. Although the risk of autism was associated with otitis media and treatment with antibiotics, we found little evidence of a synergistic effect between otitis media infections and treatment with antibiotics. Autism Res 2018, 11: 1432-1440. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We investigated whether otitis media ear infections and antibiotic treatment were associated with autism spectrum disorder. Autism was more common in children who had had an otitis media infection or who had been treated with antibiotics. Given the observational nature of our data, our study cannot be used to conclude that otitis media or use of antibiotics cause autism, as our findings may be subject to unobserved confounding.
Autism research : official journal of the International Society for Autism Research, 2018 · doi:10.1002/aur.2015