Herpes 1 is a childhood illness. Most children experience there first herpes infection before their third birthday. During the primary illness, the child can have a high fever and multiple canker sores on the tongue and gums. The children can feel miserable, and not want to eat. Most children are treated at home, but on occasion a child needs IV hydration. The canker sores start to heal after about a week. As with any viral illness, many children have a version of 'primary' herpes 1 illness. There might be a non-specific fever and decreased appetite. The parents might not have brought them to the doctor and realized that they had a canker sore in the back of the throat.

The first herpes 1 illness is usually acquired from a playmate or relative with a cold sore. This is an illness that can pass from mother to child through the generations.

Cold sores are a form of recurrent herpes. The virus, which was acquired years before, reappears, usually on the lip, but sometimes on the cheek, behind the ear, or other part of the body. Stress, fatigue, or an intercurrent viral illness can all act as triggers for the reappearance of a cold sore.