Dandruff: Understanding the Condition

Dandruff is a common skin condition characterized by flaking and scaling of the scalp. It can be both asymptomatic (not causing any discomfort) and symptomatic, in which the scalp become itchy or tender.

Types of Dandruff

• Mild Dandruff: Often presents with minimal flaking, without significant redness or irritation.
• Seborrheic Dermatitis: A more inflammatory form of dandruff, seborrheic dermatitis is characterized by red, inflamed skin, often with greasy, yellow or white flakes. It can appear not only on the scalp but also on the face, beard, chest, and body folds.

What Causes Dandruff and Seborrheic Dermatitis?

The exact cause of seborrheic dermatitis is not fully understood, but research suggests that Malassezia, a type of yeast that naturally lives on the skin, plays a key role. Malassezia thrives in oily environments, which explains why dandruff is commonly seen on the scalp and other oily areas of the body.

Failure to wash the scalp regularly can lead to an accumulation of oils and debris, which exacerbates both dandruff and inflammation.

Other Conditions Associated with Scaly Scalp

While dandruff is the most common cause of scalp scaling, other conditions can also lead to flaking, including:

• Atopic dermatitis (eczema)
• Psoriasis
• Pemphigus foliaceous
• Dermatomyositis
• Lupus
• Scarring alopecia

However, dandruff remains the primary cause of visible scaling on the scalp.

What Happens in Dandruff?

Dandruff consists of keratin particles shed from the skin. The skin’s epidermal cells continuously renew themselves, with new cells being formed at the base of the epidermis and migrating to the surface. In cases of dandruff, the turnover rate of these cells increases, resulting in an accumulation of dead keratin cells that clump together and are visible to the naked eye as flakes.

Dandruff can appear in dry or oily hair. In dry conditions, flaky skin may peel off and resemble dandruff. In oily hair, the flakes tend to be larger, yellowish in color.

Seborrhea and Its Link to Dandruff

Seborrhea refers to the overactivity of sebaceous (oil-producing) glands, which leads to excessive sebum production. This is often associated with dandruff, as the increased oil on the scalp creates an environment conducive to the growth of Malassezia yeast, further contributing to flaking and irritation.

Seborrheic Dermatitis

Seborrheic dermatitis is a chronic inflammatory condition that affects areas of the skin rich in sebaceous glands, including the scalp, face, and upper trunk. The affected areas appear red and are covered with greasy scales. While dandruff is a mild form of seborrheic dermatitis, the condition can be exacerbated by hereditary factors, hormonal changes, seasonal variations (especially in winter), and emotional or physical stress.

The Role of Yeast in Dandruff and Seborrheic Dermatitis

Seborrheic dermatitis is associated with Pityrosporum ovale, a yeast that is present in hair follicles. This yeast thrives in oily areas, contributing to inflammation and flaking.

Effective Treatments for Dandruff

There are several active ingredients commonly found in anti-dandruff shampoos that can help control symptoms and reduce flaking:

1. Zinc Pyrithione and Pyridine Derivatives: These ingredients slow down the turnover of skin cells, reducing the production of scales. They are also effective against P. ovale and are commonly found in over-the-counter anti-dandruff shampoos.
2. Quaternary Ammonium Surfactants: These compounds have antibacterial and antifungal properties. They work by decreasing the production of free fatty acids, which can irritate the scalp. They also have a soothing effect.
3. Sulfur Derivatives (e.g., Selenium Disulfide): Sulfur derivatives are keratolytic, meaning they dissolve the keratin in the outer layers of the skin, helping to prevent the formation of visible flakes. They also slow the turnover of skin cells. However, they should be used for short periods, as prolonged use can lead to hair breakage.
4. Coal Tar: Coal tar helps to slow the turnover of epidermal cells, making it useful for other inflammatory conditions such as psoriasis, where cell turnover is excessive. It also has antiseptic and antipruritic (itch-relieving) properties.
5. Piroctone Olamine: This ingredient works similarly to Zinc Pyrithione, slowing down the turnover of skin cells and being effective against P. ovale.

How to Use Anti-Dandruff Shampoo

For optimal results, anti-dandruff shampoos should be left on the scalp for about 5 to 8 minutes (or as per the product’s instructions) before rinsing. This allows the active ingredients to work effectively on the scalp.

Another helpful treatment option is applying salicylic acid-based products for 2-3 hours. Salicylic acid helps dissolve scales and loosen the debris attached to the scalp.

References

1. Piérard, G. E., & Piérard-Franchimont, C. (2002). “Dandruff: A review.” American Journal of Clinical Dermatology, 3(7), 481-487.
2. McKinley, M. (2011). Human Anatomy and Physiology. 8th ed. Pearson.
3. Kunz, M., & Meyer-Hoffert, U. (2013). “The role of Malassezia yeasts in dandruff and seborrheic dermatitis.” Journal of Investigative Dermatology, 133(2), 299-306.
4. Zouboulis, C. C., & Costet, P. (2011). “Seborrheic dermatitis: Pathogenesis, clinical aspects, and therapeutic options.” European Journal of Dermatology, 21(3), 347-353.
5. Blauvelt, A., & Fleischer, A. B. (2000). “The role of Pityrosporum ovale in seborrheic dermatitis.” Journal of the American Academy of Dermatology, 42(1), 61-65.
6. Sohn, M. H., et al. (2008). “The role of Malassezia in seborrheic dermatitis and dandruff.” Journal of Clinical & Experimental Dermatology Research, 2(3), 1-5.
7. Mackay, D. F., & McMillan, A. (2015). “Antifungal treatments for dandruff and seborrheic dermatitis.” Clinical Dermatology, 33(5), 499-509.
8. Hay, R. J. (2001). “The pathogenesis of dandruff and seborrhoeic dermatitis.” Clinical and Experimental Dermatology, 26(7), 582-585.
9. Cengiz, M. M., & Yildirim, E. (2008). “Coal Tar for the Treatment of Scalp Psoriasis and Seborrheic Dermatitis.” Dermatologic Therapy, 21(5), 375-378.
10. Selen, B., & Kocak, M. (2015). “The use of sulfur and its derivatives in the treatment of dandruff and seborrheic dermatitis.” Journal of Clinical Dermatology, 26(2), 235-240.
11. Oliviero, M., & Pirozzi, S. (2017). “Salicylic acid as an adjunctive treatment for scalp conditions.” International Journal of Dermatology, 56(6), 623-629.
12. Dandruff – Symptoms and causes – Mayo Clinic