Fremanezumab-associated injection site alopecia.

Calcitonin gene-related peptide (CGRP) inhibitors, in the form of injectable monoclonal antibodies, are a newer class of drugs for the prevention of migraine headaches. In clinical trials, they have been found to be effective with good tolerance and few adverse effects. Alopecia has been increasingly noted as a post-marketing event associated with CGRP inhibitor injectables. Of the case reports available on this topic, alopecia has commonly been localised to the scalp and associated with erenumab use; however, not as much has been reported for fremanezumab nor for injection site-related alopecia. We report an occurrence of persistent lower extremity localised injection site alopecia in a patient within our headache clinic who used fremanezumab. The possible mechanism of alopecia may be related to the failure of hair follicle immune privilege in the absence of CGRP immunomodulatory effects.