Unilateral facial paralysis after treatment of secondary syphilis.

Bell's palsy is an acute facial paralysis of unknown etiology. Infections including syphilis have been implicated as causes for peripheral facial paresis. The Jarisch-Herxheimer reaction is an acute worsening of skin manifestations and systemic symptoms occurring after administration of antimicrobial therapy for spirochetal infections. Although rare, neurological signs can present as part of the Jarisch-Herxheimer reaction. The authors report a case of Bell's palsy experienced by a patient shortly after treatment with penicillin for secondary syphilis and propose that this acute unilateral peripheral facial paralysis was a Jarisch-Herxheimer reaction in response to therapy.