You've probably seen a million ads dramatizing the “repulsive” appearance of these small white flakes on dark hair, a dark blouse, or shirt. Dandruff flakes represent scales from the scalp. The word dandruff probably originates from the combination of "dander," which refers to skin scales on animal fur or bird feathers and the word "hurf," which originates from a 500-year-old English word for crust. A few particles of dandruff go unnoticed. Too much, though, can cause embarrassment. As much as 50% of the population is troubled by the dandruff nuisance.
Not all white flakes are dandruff. White specks can arise from dried hair mousses, sprays, or nourishers that flake off your hair and then fall on your shoulders.
And contrary to popular belief, most people with dandruff don't actually have a "dry scalp." Some people avoid shampooing regularly, believing regular washing leads to a dry scalp. They believe that such washing damages their hair, or that washing will destroy their hairdo. But scale from an unwashed scalp can collect and then appear as excessive dandruff. The scalp skin is full of follicles with active sebaceous glands producing large quantities of grease. So regular shampooing is a must if you want to fight dandruff.
Probably the most common cause of dandruff is a skin disease called "seborrheic dermatitis." This condition can produce an itchy, scaling red rash on the scalp, in the ears, on the upper eyelids, brows, forehead, in the folds that extend from the nose to the corners of the mouth, and occasionally on the mid-chest and mid-back.
Many people can control their underlying dandruff (seborrheic dermatitis) with medicated shampoos available without a prescription. These anti-seborrhea shampoos contain a variety of chemicals that are beneficial in diminishing the inflammation and scaling of seborrhea. They include ketoconazole (Nizoral), salicylic acid, selenium sulfide (Dandrex, Exsel, Selsun Blue), tar extract (T/Gel), and zinc pyrithione (Head and Shoulders, Clear). Exactly how they work is speculative.
The idea that botanical organics are superior over so-called synthetic substances is a creation of popular culture and the Internet. The idea that a plant recently harvested from a personal garden might cure a real ailment and is perfectly safe does have a romantic appeal. There is minimal evidence to support the notion, though many plants contain pharmacologically potent chemicals that when purified and standardized become FDA-approved medications. Beware of backyard amateur pharmacy.
Using a medical shampoo is not that complicated. Place a modest amount of shampoo in the palm of one hand and vigorously rub it into your wet hair. Then carefully massage the scalp with your fingertips. The shampoo should remain on the scalp for about five minutes and then get completely rinsed out. Since some of these shampoos may have a trace of unpleasant odor, it would be a good idea to apply a favorite conditioner afterward. Tar shampoos can stain gray or bleach hair a brownish-yellow hue, which some may find undesirable.
There is very little evidence that sunlight affects dandruff one way or the other. Unless your scalp is balding, it is doubtful ultraviolet light could reach the skin. There is at least one report of mountain guides having more seborrheic dermatitis than expected. It was presumed that there might be a causal relationship between ultraviolet exposure and the disease. Sun exposure, therefore, should not be recommended for controlling dandruff.
Scalp dermatitis should be seen by a doctor if it is not improved by nonprescription medicated shampoos. Since seborrheic dermatitis is the most common cause of dandruff, it may be necessary to supplement shampooing with topical steroids, lotions, or antifungals. Both seem to work well to control seborrheic dermatitis, yet a permanent cure for this condition is unavailable. Treatment often continues indefinitely but at gradually decreasing frequency.
The cause (or causes) of seborrheic dermatitis remains obscure. The role of Malassezia yeasts appears essential, but since they are normal components of the skin's microbiome, the mechanism of disease is unclear.
There may be a seasonal relationship to the severity of seborrheic dermatitis. In one study in Japan, it was found that seborrhea was correlated with lower humidity.
Seborrheic dermatitis can be confused with contact dermatitis, atopic dermatitis, and psoriasis. In order to differentiate these conditions, a patient's entire skin would need to be evaluated and, rarely, a piece of skin might need to be obtained surgically (skin biopsy) and submitted for a pathological evaluation. Seborrheic dermatitis seems more severe in those with significant central nervous system problems, including dementia, trauma, and stroke. Immunosuppressed patients often have severe seborrhea.
An itchy scalp can be due to many reasons. Patients with head lice characteristically itch. Visualization of the six-legged louse or its egg case attached to a hair shaft is sufficient to confirm the diagnosis. Contact dermatitis caused by allergies to hair coloring, permanent wave solutions, or shampoo preservative can occasionally cause confusion with seborrheic dermatitis because it often is associated with excess scaling on the scalp. Rarely, fungal infections can cause a non-inflammatory scaling dermatitis of the scalp most often seen in the third world that looks very similar to seborrheic dermatitis. A microscopic examination of the scale using potassium hydroxide will demonstrate the fungus.
Seborrheic dermatitis in infants is called cradle cap. It can affect other parts of the body as well, including the creases in the diaper area. It almost always spontaneously remits by 6 months of age. Treatment with mild shampoos usually is sufficient. Topical antifungals and weak topical steroids prescribed by a physician may rarely be required to treat it.
The bottom line is that dandruff can be a sign of scalp inflammation, most often seborrheic dermatitis, which is not contagious, is easily treated and incurable.
IMAGES PROVIDED BY:
- Don Hammond / Design Pics Inc
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- Noel Hendrickson / Stockbyte
- Peter Frank / Fancy
- CHASSENET / BSIP
- Le Studio / Brand X Pictures
- B BOISSONNET / BSIP
- Janice Carr / BSIP
- Dr. Hercules Robinson / Phototake
- Don Hammond / Design Pics Inc
- Biophoto Associates / Photo Researchers
- Acta Dermato-Venereologica
- American Academy of Dermatology Association: "How to Treat Dandruff." "Seborrheic Dermatitis: Overview."
- Archives of Disease in Childhood 2004
- Clinics in Dermatology
- Dermatology: "High Prevalence of Seborrheic Dermatitis on the Face and Scalp in Mountain Guides"
- DermNet NZ: "Skin conditions associated with Malassezia."
- International Journal of Cosmetic Science
- Journal of Clinical Aesthetic Dermatology
- Journal of Dermatology
- Skin Therapy Letter: "Therapeutic Update on Seborrheic Dermatitis"
- wikiHow: "How to Shampoo Your Hair"