Dandruff is the most common head problem! But it is not contagious and besides this is the natural ability of the scalp. Dead cells that were previously part of the scalp make up dandruff. Slight dandruff is inevitable. The problem only arises when the presence of dead cells in the form of flakes suddenly increases. Doctors are still debating the cause of dandruff. Many researchers believe this is due to the overgrowth of the bacteria Pityrosporum Ovale, which commonly live on the scalp. They make up the main part of the skin flora. You suffer from dandruff when the normal limit of 46% of Pityrosporum is increased to 74%. Factors such as emotional and physical stress cause dandruff to grow. Also, the growth of dandruff increases during winter compared to summer for most people. Hair gels increase dandruff.