Susac syndrome (SS) is a central nervous system vasculitis characterized by the clinical triad of encephalopathy, sensorineural hearing loss, and visual disturbance caused by branch retinal artery occlusion. It is considered as an inflammatory disorder, and an autoimmune etiology is suggested. A 29-year-old man with a history of recent cocaine abuse developed the clinical features of SS. Toxicological analysis including hair testing revealed that cocaine had been adulterated with levamisole. After an initial clinical improvement following corticosteroid therapy, the introduction of mycophenolate mofetil was justified a few weeks later by the progression (or relapse) of the retinal injury, followed by complete recovery. The presence of levamisole has been documented in patients with multifocal inflammatory leukoencephalopathy (MIL). Further investigations are needed to determine if levamisole as an adulterant of cocaine could also play a role in the development of rapidly progressive leukoencephalopathy in young men, with Susac or Susac-like syndromes as possible variants of MIL.