First of all, it’s about understanding what dandruff is. So, it seems that every 20-30 days the scalp skin renews itself. Dander, which is small pieces of dead skin, appear at the hairline. But sometimes this cycle can be shortened to 5 days, and in this case the dead skin is not eliminated quickly enough, which causes the formation of dandruff. The imbalance in this cycle is caused by a microorganism called pityriasis. This kind of infection is common because it affects about one in two people¹. It does not present any risk for the affected person, but is not very aesthetic. Next, we must differentiate between oily dandruff and dry dandruff. Dry dandruff, which appears on dry, dehydrated scalps, is easier to treat than oily dandruff. The latter cling to the roots and form large yellowish patches, promoting the development of bacteria. Sometimes dandruff is very itchy², caused by inflammation. Finally, it seems that men and adolescents are the most affected by the appearance of dandruff.³.

French Society of Dermatology. Dandruff. Dermato-info.fr. 2014 James R. Schwartz, Yvonne M. DeAngelis, Thomas L. Dawson. Dandruff ans seborrheic dermatitis: a head scratcher. Chapter 12. Elewski BE. Clinical diagnosis of common scalp disorders. J Investig Dermatol Symp Proc. 2005 Dec; 10 (3): 190-3.