Antibiotic use and risk of multiple sclerosis

Alvaro Alonso, Susan S. Jick, Hershel Jick, Miguel A. Hernán

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Some reports suggest that bacteria, including Chlamydophila pneumoniae, could be involved in the etiology of multiple sclerosis. If that is true, persons who used antibiotics active against these bacteria, compared with nonusers, might be at lower risk of multiple sclerosis. Using a 1993-2000 case-control study nested in the United Kingdom-based General Practice Research Database cohort, the authors identified 163 multiple sclerosis cases who were followed up for at least 3 years before their first symptoms (the index date). Up to 10 controls matched to the cases by age, sex, general practice, and time in the cohort were selected. Exposure to antibiotics was assessed through computerized medical records. Overall antibiotic use or use of antibiotics against C. pneumoniae was not associated with multiple sclerosis risk. However, use of penicillins in the 3 years before the index date decreased the risk of developing a first attack of multiple sclerosis (odds ratio = 0.5, 95% confidence interval: 0.3, 0.9 for those who used penicillins for ≥15 days compared with no use). In conclusion, use of antibiotics active against C. pneumoniae was not associated with a decreased risk of short-term multiple sclerosis. The observed lower risk of multiple sclerosis for penicillin users needs to be confirmed in other populations.

Original languageEnglish (US)
Pages (from-to)997-1002
Number of pages6
JournalAmerican journal of epidemiology
Issue number11
StatePublished - Jun 2006

Bibliographical note

Funding Information:
This work was funded by the National Multiple Sclerosis Society (grant RG 3236A1/1). Dr. Alonso was supported by a Fulbright fellowship and an MMA Foundation grant.


  • Anti-bacterial agents
  • Chlamydophila pneumoniae
  • Multiple sclerosis
  • Prospective studies


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