​What are dandruff and seborrheic dermatitis?

Dandruff and seborrheic dermatitis are chronic skin conditions that cause scaling of the skin, which may or may not be accompanied by itching. Dandruff is a milder form of seborrheic dermatitis, affecting only the scalp, whereas seborrheic dermatitis also affects other parts of the body.​^1,2,3,4

What are the symptoms?

Seborrheic dermatitis appears as irregular inflammed patches with dull, yellowish, greasy large scales, often with itching. It occurs mainly in areas with more oil-producing glands, including the scalp, face, upper chest and upper back. The armpits and groin area may also be affected.^1,5

Seborrheic dermatitis in infants is known as cradle cap. This appears as thick yellow crusts on the face and neck, behind the ears, in the folds of skin, and also as a stubborn diaper rash. Cradle cap does not usually cause itching.³

Dandruff on the scalp is diffuse and appears as smaller dry or greasy, white or grey scales with little to no inflammation. Itching is usually present.^1,6

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What are the causes?

The cause is not clear, but is linked to a type of yeast that is normally found on human skin. Symptoms come and go, and may worsen with emotional or physical stress, cold weather (during winter months), hormonal changes and illness.^2,3,4

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Who are affected?

Dandruff is uncommon in children, begins to appear at puberty and becomes more common until the early twenties, then begins to decline. It is uncommon in the middle-aged and elderly.⁴

Cradle cap mainly affects infants from birth to 3 months old, and usually resolves by the time the infant is 8 to 12 months old.^1,3

Seborrheic dermatitis is more common in men and occurs between 30 to 70 years old, with more cases happening between 30 to 40 years old.^2,5 Individuals with oily skin, personal or family history of seborrheic dermatitis, rosacea or psoriasis, history of organ transplant, infected with the human immunodeficiency virus, certain neurological and psychiatric disorders including Parkinson's disease, stroke or heart attack, alcohol abuse and those using certain medications including lithium, interferon and psoralen have higher risk of developing dandruff and seborrheic dermatitis.^5,6,7,8,9

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How are dandruff and seborrheic dermatitis diagnosed?

There is no specific test for diagnosing dandruff or seborrheic dermatitis. Diagnosis is usually based on the person's history and physical examination. Rarely, a skin biopsy may be done to rule out other similar skin conditions.³

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How do i treat dandruff and seborrheic dermatitis?

Dandruff and seborrheic dermatitis are long-term conditions that cannot be cured. However, there are many effective treatments available over-the-counter and from the pharmacy to keep the symptoms under control.

Self-treatment is not recommended if the person affected is less than 2 years old, except in the case of cradle cap. If symptoms do not improve or worsen after 2 weeks of using over-the-counter and pharmacy medicines, see a doctor for further treatment.⁶

Cradle cap

Cradle cap can be treated by washing the scalp daily with a non-medicated baby shampoo. Apply a small amount of baby oil or olive oil to loosen the scales. Gently ​massage the scalp with a soft toothbrush to remove the scales, then shampoo again with a non-medicated baby shampoo. Repeat daily until the thick scale disappears.^2,3

Topical medications

Dandruff and seborrheic dermatitis can be treated with medicated shampoos. After massaging the shampoo into the scalp, leave on for 5 minutes before rinsing thoroughly and repeating the process. Leaving the shampoo in contact with the scalp for the recommended period of time is important to ensure that the treatment is effective. If one type of shampoo does not improve the condition after 4 to 6 weeks, a different medicated shampoo may be used. ^3,10

Medicated shampoos may contain one or a combination of the following medications: zinc pyrithione, selenium sulphide, coal tar, salicylic acid and ketoconazole. Steroid creams may also be applied to relief the itch and inflammation in seborrheic dermatitis. Besides ketoconazole, the other medications may be used in children from 2 years old and above.

Follow closely the instructions of use as stated on the product. Avoid applying medicated shampoos on broken or abraded skin. If the shampoo gets into the eye, flush immediately with plenty of water. If significant skin irritation occurs while using any product, stop using and consult a doctor. 

Side effects

Selenium sulphide may discolour hair, especially blond, grey or dyed hair. Rinse thoroughly after use to avoid this effect. Frequent use may also result in a residual odour and an oily scalp.⁶

Coal tar has an odour that may be considered unpleasant. It can stain the skin and hair, especially light-coloured and artificially bleached hair. It may also stain clothing and jewelry. Avoid sun exposure to the scalp and other parts of the body where coal tar has been applied. There is a small risk that coal tar may increase the risk of skin cancer. Avoid using over a large area of the body or for prolonged periods unless instructed by your doctor.^1,4,11,12

When large amounts of a product containing salicylic acid is used, significant absorption into the body may occur, causing toxicity with symptoms including nausea, vomitting and ringing in the ears. Avoid using these products over large areas of the body.^4,13

Ketoconazole should not be used in children below 12 years old. Side effects include acne, hair loss, abnormal hair colour or texture and oiliness or dryness of hair and scalp.^14,15

Excessive and prolonged use of steroid creams may cause thinning of the skin, acne, excessive hair growth, pigmentation changes and stretch marks. They may also cause increase in blood sugar levels and affect certain hormones in the body, resulting in a symptom of 'moon-face' with a condition known as Cushing's syndrome. To prevent these, apply a thin layer of the cream no more than twice a day, and for not more than seven consecutive days. Avoid applying to large areas of the body.^1,6,16

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Where can i find out more?

Any further inquires can be directed to your doctor, or to a community pharmacist.

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Disclaimer

Information provided by this patient information leaflet is solely for informational purposes only and is not intended as a substitute for the advice provided by your physician, pharmacist or other healthcare professional. You should not use the information for diagnosis or treatment of a health problem or disease. Always speak with your physician, pharmacist or other healthcare professional before taking any medicine or supplement, or adopting any treatment for a health problem. Under no circumstances will Pharmaceutical Society of Singapore be liable to any person for damages of any nature arising in a way from the use of such information.​

 

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​References

[1] Berk T, Scheinfeld N. Seborrheic Dermatitis. Pharmacy and Therapeutics. 2010;35(6):348-352.

[2] Karen M. Seborrheic Dermatitis. MSD Manual Professional Version. Updated 2014 Oct.

[3] Dennis S, Robert PD, Joseph F, Rosamaria C. Patient information: Seborrheic dermatitis (including dandruff and cradle cap) (Beyond the Basics). UpToDate. Updated 2015 May 7.

[4] W. Steven Pray. Dandruff and Seborrheic Dermatitis. US Pharmacist. 2001;26(4).

[5] Plewig G, Jansen T. Seborrheic Dermatitis, In: Freedberg IM, Eisen AZ, Wolff K, et al., eds. Fitzpatrick's Dermatology in General Medicine, 6th ed. New York: McGraw-Hill, Inc; 2003:1482-3.

[6] Steven AS. Scaly Dermatoses. In: Handbook of Nonprescription Drugs, 16th ed. Washington DC: American Pharmacists' Association; 2009. p. 643-656.​

[7] Habif TP, Campbell JL, et al. "Seborrheic dermatitis." In: Dermatology DDxDeck.China, Mosby Elsevier: 2006, p. 40

[8] Amanda Oakley. Seborrheic Dermatitis. Updated July 2014.

[9] Mallal SA. The Western Australia HIV Cohort Study, Perth, Australia. J Acquir Immune Defic Syndr Hum Retrovirol. 1998;17 (Suppl 1):S23-S27.​​

[10] Odom RB, James WD, Berger T. Andrews Diseases of the Skin: Clinical Dermatology, 9th ed. Philadelphia: WB Saunders; 2000.​

[11] Hay RJ, Graham-Brown RAC. Dandruff and seborrheic dermatitis: causes and management. Clin Exp Dermatol. 1997;22:3-6.

[12] Lin AN, Moses K. Tar revisited. Int J Dermatol. 1985;24(4):216-218.

[13] Brodell RT, Cooper KD. Therapeutic shampoo, In: Wolverton SE, ed. Comprehensive Dermatologic Drug Therapy. Philadelphia: WB Saunders; 2001:647-58.

[14] Nizoral® cream product insert [updated 2014 Sep 11].

[15] Nizor​​al® shampoo product insert [updated 2014 Mar 3].​​

​[16] Josse G, Rouvrais C, Mas A, et al. A multitechnique evaluation of topical corticosteroid treatment. Skin Res Technol. 2009;15(1):35-39.​