After consulting Dr. Jeffrey Benabio, a dermatologist in San Diego, California, and author of the Derm Blog, for general information about itchy scalps. He shared the following:

Itchy scalp can be a frustrating problem. There are several things that can cause it. Dandruff is the most common. Dandruff is caused by overgrowth of yeast on your scalp. The yeast triggers inflammation and itching. It usually causes flaking, but not always. When the scalp is red and flaky from dandruff, we often call it seborrheic dermatitis, but the cause is the same.

Allergic contact dermatitis is also a common cause of itchy scalp. Sometimes, people develop an allergy to their hair color or to their shampoo, conditioner or hair products. This is often intensely itchy and sometimes spreads to the back of your neck or your back (depending on the length of your hair).

Inflammation of the hair follicles or bacterial infection of the scalp can also cause itching. Usually, people with this problem have acne-like bumps or pustules in the affected areas.

Other causes of itchy scalp are uncommon. Inflammatory and hair loss conditions of the scalp are rare but can also cause itching. There are many of them; discoid lupus and hot comb alopecia are two examples. They always have areas of obvious hair loss.

Systemic, or whole body, diseases can sometimes cause scalp itching. Common diseases such as psoriasis and rare conditions such as dermatomyositis can cause itchy scalp. Both also cause redness and flaking.

Sometimes, frankly, we just don't know what causes the itching. Washing your hair too infrequently is more likely a problem than washing too much, as the scalp rarely dries out. Using anti-dandruff shampoos two or three times a week and over-the-counter anti-itching treatments such as Scalpicin usually relieves the problem.