The exact cause of Fox-Fordyce disease is unknown.

The apocrine glands (sweat glands) are the site of the Fox-Fordyce disease.

In Fox-Fordyce disease abnormalities affecting the apocrine sweat glands causes inflammation, and enlargement of the glands and the characteristic intense itching.

White, Stephen MD, William, James MD. "Fox-Fordyce Disease."

Fox-Fordyce disease, or apocrine miliaria, is a chronic blockage of the sweat gland ducts with a secondary, non-bacterial inflammatory response to the secretions and cellular debris in the cysts.

When seen as a streak of individual glands along the interface between the skin of the lip and the vermilion border, the terms Fox-Fordyce disease and Fordyce's condition have been used.

Although Fox-Fordyce disease is relatively uncommon in the United States, it is exacerbated by heat, humidity, and areas of friction (arm pits), thus it is more prevalent in tropic-like conditions.