Dandruff results from the abnormal proliferation of a micro-organism from the Malassezia family, which is a yeast. This phenomenon causes skin cells in the epidermis to renew much too quickly. They appear in clumps on your scalp, forming large dandruff or patches that fall off or become sticky. They look oily and yellowish-grey.
This can be accompanied by an extremely irritated scalp and intense itching. Dandruff is visible in your hair and, in most cases, falls onto your neck and shoulders, particularly during styling. Fatigue, stress, pollution and the winter are factors that can promote or increase malassezia furfur proliferation and thus the appearance of dandruff.