The infection is caused by Herpes Simplex virus and often occurs in children. Blisters, erosions and crusting may be seen on the lips and buccal mucosa. Commonly, the child also has fever, malaise and enlarged lymph nodes. It is infectious. Severe attacks may require oral antiviral agent. It usually takes 2 weeks for the blisters and erosions to clear. Recurrent attacks can occur but the skin lesions are usually less severe.