Science and Education Publishing American Journal of Medical Case Reports 2374-216X 3 5 2015 04 23 Facial Herpes Simplex Virus Type 1 Infection in a Patient with Multiple Sclerosis on Fingolimod 144 145 EN Racosta Juan Manuel McEwan Lynn Kremenchutzky Marcelo Carlos Morrow Sarah Anne University of Western Ontario, London, Ontario AJMCR2015357 10.12691/ajmcr-3-5-7 2015 03 18 2015 04 15 2015 04 23 Fingolimod is an oral disease-modifying therapy for relapsing multiple sclerosis widely used in Canada as a second-line therapy. Fingolimod increases the risk of infections given its dose-dependent reduction of peripheral lymphocytes, due to the reversible sequestration in lymphoid tissues. We present a case of disseminated facial Herpes Simplex Virus type I infection in a patient using fingolimod, with an atypical distribution of the eruption, likely due to the concomitant exposure to sunlight and application of sunscreen. This case report provides insight about a novel mechanism of disseminationof Herpes Simplex Virus type I, which generally enters damaged epithelium or mucosal surfaces secondary to abrasions or trauma. Since Herpes Simplex Virus type I infection tends to disseminate and is accompanied by visceral involvement in immunosuppressed patients, close surveillance of viral infections and the prompt administration of full-dose antiviral therapy in this population is advised.