👉 Seborrheic dermatitis is a skin condition that causes patches of skin to become rough, red, and scaly. These patches can appear anywhere on the body, but they are most common on the scalp, face, neck, hands, and feet. Seborrheic dermatitis typically starts in childhood, but it can also occur at any age. It is caused by an overproduction of sebum (oil) in the skin, which causes the skin to become too oily