Hair loss can be related to allergic reactions - this is known as allergic alopecia. Allergies to ingredients in hair care products sometimes cause inflammatory reactions on the skin. As a result, this leads to hair loss and excessive hair breakage. The primary symptoms of allergic diseases of the scalp are dryness and itching. Associated with technological and civilisation advances, increased exposure to unfavourable environmental factors promotes further damage to the skin's protective barrier. Symptoms of excessive epidermal dryness in the scalp take the form of varying degrees of dandruff exfoliation. Both immunological and non-allergic factors play a major role in the course of allergic diseases, such as adverse weather conditions, overexposure to detergents, frequent hot and long baths.