Clinically, two different types of pityriasis are recognized:

1) dry or simple pityriasis, in which the scalp is covered in small, very fine flakes that are easily detached and end up covering clothes with dust, with the presence of normal skin and modest itchiness. It is often provoked by slight seborrheic dermatitis, which is nothing other than an inflammation of the skin. This irritation occurs in areas that are rich in sebaceous glands, which appear reddened and scaly. These symptoms may also be associated with androgenetic alopecia (pattern hair loss).

2) greasy or pityriasis steatoides, in which the scalp is covered in thicker, yellow, greasy flakes, which adhere to the often red and sweaty scalp, with the presence of moderate itchiness and reduced hair loss. It has quite an unsightly appearance. It is almost always caused by a rapid development of some cells of the superficial layer of the epidermis. This type of dandruff is also present in those afflicted by contact eczema or psoriasis. The scalp is easily irritable, which causes the itchiness and correspondent flaking. The size varies from person to person, and usually the condition occurs around the temples, forehead and ears. It is mostly seasonal and occurs with greater intensity in the colder seasons, then abating during the summer.

The main organisms that are found in dandruff are aerobic bacteria, acne bacillus (corynebacterium acnes) and various Pityrospori (Malassezia). The most common is undoubtedly Malassezia and the more serious the flakiness, the greater the number of superficial or follicular microorganisms with free and filamentous forms will be.
In conclusion, we can say that Malassezia is quantitatively the most common microorganism associated with dandruff. A reduction in Malassezia caused by a wide spectrum of antimycotic agents leads to a reduction the clinical aspect of dandruff and the objective measurement of flakiness. On the other hand, a recolonization of the microorganisms leads to the re-appearance of dandruff.

Many anti-dandruff hair treatments, shampoos and ltions are available for sale. These may contain just germicides to combat microorganisms, or keratolytics to eliminate dead cells and reduce subsequent flaking. Prolonged use of keratolytics may however cause a reduction in the corneum layer and increase seborrhea. Acid-based solutions exist that are presented as strong therapies and are not, however, always tolerated. We can confirm that the most practical solution is the increase in frequency of washing and the use of specific antimycotic shampoos combined with lotions.