The perpetrator of dandruff is the fungus Pityrosporum ovale (also known as Malassezia furfur) that is not visible to the naked eye and is totally harmless under normal circumstances. It is in fact present on the scalp of every human being.
The problem occurs when the fungus excessively replicates. This leads to the formation of white scaly flakes, which are usually accompanied by severe itching.
The reason for the excessive multiplication of the fungus can be overactive sebaceous glands, hormonal disorders, stress, adverse weather conditions, allergies and excessive sweating.
As have already been said the reproduction of fungus Pityrosporum ovale can be triggered by various external (nutrition, climate, headgear…) and internal (hormonal changes, increased sebum production, stress…) factors. Excessive propagation of fungi most often occurs when entering puberty and disappears during the mid-thirties.
Oilier the scalp is, more excessively will the fungus propagate. The result will be oily and slightly yellowish flakes, which can be relatively large. Greasy flakes are very favorable environment for the fungus Pityrosporum ovale and bacteria that cause inflammation and skin itching.