Seborrheic dermatitis, also known as seborrheic eczema, is a chronic inflammatory skin disease that occurs in areas with excessive sebum secretion, such as the face, chest, and back. Seborrheic dermatitis is not the same as seborrheic hair loss, although some patients with seborrheic dermatitis may also experience hair loss. Generally, seborrheic dermatitis starts on the face and then spreads downwards to other areas, accompanied by varying degrees of itching, and is commonly seen in adults and newborns. Seborrheic dermatitis is associated with factors such as psychological stress, dietary habits, deficiencies in B vitamins, alcohol consumption, and sleep deprivation. As it often starts or is primarily localized on the scalp, symptoms can worsen and spread to other areas. The disease tends to occur in areas that are oily, hairy, and sweaty. As the sebaceous glands open into the hair follicles, the initial skin lesions of seborrheic dermatitis are usually small, red papules around the hair follicles. As the condition progresses, these papules can develop into red patches. Some patients may also have oily scales or crusts, as well as varying degrees of hair loss.