According to MedlinePlus, an itching head is a common sign of seborrheic dermatitis, a skin condition that causes itchy scales on the scalp and other areas of the body. While the specific cause of seborrheic dermatitis is unknown, it is linked to weakened immune systems, nutrient deficiencies and conditions of the nervous system. Symptoms include white to yellow-colored scales, itching, redness and hair loss.
The Mayo Clinic explains that dandruff is a condition that causes an itching head and is caused by a variety of factors, including sensitivity to hair products, skin conditions such as eczema, infrequent shampooing and yeast infections of the scalp. Dandruff is easily treatable with over-the-counter and prescription dandruff shampoos.
According to WebMD, intense itching of the scalp is a common symptom of scalp psoriasis, a skin condition that causes raised patches on the scalp and other areas of the body. Scalp psoriasis is not contagious and is believed to be caused by a malfunction of the immune system that speeds up the shedding of skin cells. Symptoms include severe itching, scaly patches on the scalp, flaking skin and a burning sensation. Hair loss is also common with scalp psoriasis, due to intense scratching that causes the hair to break off. Scalp psoriasis is treatable with prescription medications that contain tar and salicylic acid, as well as over-the-counter shampoos and ointments.