Dandruff is flakes of dead skin that form on the scalp. As it is normal for skin cells to die and flake off, a small amount of dandruff is normal and in fact quite common. Some people, however, either chronically or as a result of certain triggers, experience an unusually large amount of flaking, which can be not only a visual nuisance, but is also often accompanied by redness and irritation. Most cases of dandruff can be treated with the proper shampoo.
Signs and symptoms
For most people, the symptoms of dandruff are unmistakable: white, oily-looking flakes of dead skin that dot your hair and shoulders and an itchy, scaling scalp.
But it’s not quite that simple – many conditions cause excessive skin scaling, including:
Dry skin. Simple dry skin – the kind you get in winter when the air is cold and rooms are overheated – is by far the most common cause of itchy, flaking skin. But flakes from dry skin are generally smaller and less oily than those caused by dandruff.
Seborrheic dermatitis. This condition, a frequent cause of dandruff, is marked by red, greasy skin covered with flaky white or yellow scales. Seborrheic dermatitis affects not only your scalp but also other areas rich in oil glands, such as your eyebrows, the sides of your nose and the backs of your ears, your breastbone, your groin area, and sometimes your armpits.
Psoriasis. This skin disorder causes an accumulation of dead skin cells that form thick silvery scales. In severe cases, your skin cracks, bleeds and may be quite painful. Psoriasis commonly occurs on your knees, elbows and trunk, but it can also extend from your scalp onto your forehead and neck.
Cradle cap (seborrheic dermatitis of the scalp). This disorder, which causes a scaling, crusty scalp, is most common in newborns, but it can occur anytime during infancy. Although it can be alarming for parents, cradle cap isn’t dangerous and usually clears up on its own by the time a baby is a year old.
Scalp ringworm (tinea capitis). This highly contagious fungal infection occurs primarily in children younger than age 10. Ringworm starts as a red sore around a hair shaft – usually on the scalp but sometimes in the eyebrows or eyelashes. Within a few days, the sore turns scaly and spreads outward in the ring pattern that gives the infection its name. The hair in the affected area usually breaks off just above the surface. Unlike dandruff, ringworm usually causes a red, inflamed scalp as well as hair loss.
Contact dermatitis. Sometimes sensitivities to certain hair-care products or hair dyes can cause a red, itchy, scaling scalp.