Isolated Bell's Palsy Associated with Ustekinumab in Crohn's Disease: Clinical Case and Review of Neurological Safety

Ustekinumab is widely used in Crohn’s disease with a favourable safety profile, and neurological adverse events are rarely reported. We report a 58-year-old man with perianal fistulising Crohn’s disease who developed acute isolated lower motor neuron facial nerve palsy one week after sixth maintenance dose of ustekinumab. Extensive evaluation excluded infectious, autoimmune, structural, and otolaryngological causes. Ustekinumab was withheld, and the patient was treated conservatively with steroids and antivirals, with complete recovery over 12 weeks. This case highlights Bell’s palsy as a rare neurological adverse event temporally associated with ustekinumab and underscores the need for vigilance and continued post-marketing surveillance.