Dandruff

DEFINITION
A person's entire body surface continuously sheds dead skin cells. The skin itself sheds every twenty-four days. Dandruff, the shedding of dead skin cells from the scalp at an excessive rate, is the result of the normal growing process of the skin cells of the scalp.

CAUSES
Dandruff is seasonal. It is most severe during the winter and mildest during the summer. 
The most common symptom of dandruff is scaling; itching is occasionally present. 
Dandruff scales usually occur as small, round, white-to-gray patches on the top of the head; however, scaling can occur anywhere on the scalp. 
The following factors may make the flaking of dandruff worse:

Excessive use of hairsprays and gels.
Improper use of hair-colouring products or excessive use of electric hair curlers
Cold weather and dry indoor heating.
Tight fitting hats and scarves.
Infrequent shampooing of the hair or inadequate rinsing.
Stress, anxiety and tension

TREATMENT
Since dandruff is a natural process, it cannot be eliminated; it can only be controlled.

Very Mild dandruff may be controlled by regularly shampooing the scalp with a very mild, non-medicated shampoo. If shampooing with a gentle shampoo does not control the dandruff, a medicated anti-dandruff shampoo can be used. Below is a list of the active ingredients, & how they act help alleviate dandruff & the products that contain them

Zinc Pyrithione
This is known as a cytostatic agent. Cytostatic agents reduce the rate of growth and multiplication of the top layer of skin on the scalp (horny cells). This slows down the scaling and dandruff. Shampoos that contain Zinc Pyrithione include Head & Shoulders.

Coal tar has been used for a long time in preparations for the skin for itchiness and dry flaky conditions. It works by reducing itching, acting as a mild antiseptic & having a keratolytic action. Keratin is a protein that forms part of the skin structure and can cause thickening of the skin when in excess. Keratolytic agents, such as coal tar, act by breaking down keratin and therefore help to reduce the excessive hardening, thickening and consequent scaling of the skin. Through its antiseptic, anti-itching & keratloytic properties it helps in cases of dandruff. Salicylic acid is also a Keratolytic and is also used in many anti-dandruff preparation such as T-Sal.

Shampoos that contain Coal Tar are T-Gel, Polytar amongst others.

Selenium Sulphide
Selenium sulphide specifically destroys a certain type of fungus called dermatophyte which causes symptoms of itchy, dry and flaky scalp. It is known as a cytostatic agent. Cytostatic agents reduce the rate of growth and multiplication of the top layer of skin on the scalp (horny cells). This slows down the scaling and dandruff. Products that contain Selenium include Selsun Suspension.
Ketoconazole
Ketoconazole is an antifungal. A fungus has been implicated in causing scalp conditions such as dandruff. The anti-fungal will actually destroy the fungus. A product that contains it is Nizoral Shampoo.