Background Monoclonal antibodies targeting the calcitonin gene-related peptide (CGRP) pathway represent a paradigm shift in migraine prevention, with generally favorable safety profiles. However, CGRP's widespread distribution and immunoregulatory functions raise theoretical concerns about potential off-target effects. Case presentation A 41-year-old woman with chronic migraine developed interstitial pneumonia seven weeks after initiating galcanezumab therapy. Extensive diagnostic workup excluded infectious, autoimmune, and implant-related causes. Bronchoalveolar lavage revealed marked lymphocytosis (73%) with inverted CD4/CD8 ratio. Complete radiological resolution occurred three months after drug discontinuation. Discussion To our knowledge this is the first documented case of interstitial lung disease associated with galcanezumab therapy. Despite methodological limitations, the temporal relationship, the distinctive immunological pattern, and resolution after cessation suggest a causal association. This finding emphasizes the need for vigilance regarding rare but potentially serious respiratory adverse events with anti-CGRP therapies.
Munafò et al. (2026) studied this question.