Dandruff is a skin condition on the scalp where there is rapid flaking. A typical feature of this condition is an itchy feeling on areas of the scalp. The condition is not an infection and cannot spread from one person to another. Although dandruff does not cause any long-term damage, it can become uncomfortable and lower self-esteem.

Dandruff is a common scalp condition that affects around one in two people worldwide. Some people believe that dandruff is the result of poor hygiene, but this is not true.


Dandruff appears when the renewal rate of our epidermis (the most superficial layer of our skin) is altered. A healthy epidermis normally renews itself every 21 days. But if this renewal occurs in less time (in about 7 days), dandruff appears. The cells of our epidermis do not have enough time to mature, so they end up falling off irregularly, causing those small particles or flakes that we call dandruff.

There are two types of dandruff:​

Dry dandruff: This is caused by hyperactivity in the renewal of the epidermis of the scalp in the form of small flakes that fall easily and are deposited on the shoulders, giving rise to an unsightly and unkempt appearance. It does not usually present with redness on the scalp, although there may be a feeling of tightness and itching.

Oily dandruff or seborrheic dermatitis: formed by larger, yellowish sheets that stick to our scalp. In these cases, it is important to treat it as soon as possible, because if it is not corrected it can lead to major problems at the hair level.

​Dandruff and psoriasis on the scalp can seem very similar since both produce flakes of skin on and under the hair. However, there are significant differences between these two conditions that can help a person get a prompt diagnosis and treatment.

Psoriasis is a chronic inflammatory condition that affects multiple body systems, including the skin, immune system, and musculoskeletal system. Key features of psoriasis are thick, itchy scales and plaques.

These skin problems often develop on the scalp. Unlike dandruff, psoriasis plaques on the scalp have a silvery sheen and look like dry flakes on the scalp. Dandruff is a less serious, chronic scalp condition. Dry skin flakes off the scalp and may fall onto a person's shoulders and clothing.

Signs and symptoms of dandruff may include:

 

• Skin flakes on the scalp, hair, eyebrows, beard or mustache, and shoulders.

• Itchy scalp.

• Scaly, crusty scalp in babies with cradle cap.

• Signs and symptoms may be more severe if you are stressed and often appear during cold, dry seasons.

https://www.news-medical.net/health/What-is-Dandruff-(Spanish).aspx

https://www.mayoclinic.org/es-es/diseases-conditions/dandruff/symptoms-causes/syc-20353850

https://www.medicalnewstoday.com/articles/es/psoriasis-o-caspa