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A Dermatological View—Scalp Irritation From Hair Care Chemicals

By: Hongbo Zhai, MD, and Howard I. Maibach, MD, University of California San Franciso; and Heidi P. Chan, MD

Posted: January 4, 2013, from the January 2013 issue of Cosmetics & Toiletries.

Scalp irritation is defined as dermatitis of the scalp¹ caused by the contact of chemical, physical or biological agents, although endogenous factors such as impaired barrier function and pre-existing dermatitis may also play a role.² Its clinical manifestations can range from mild to severe, with signs and symptoms such as erythema, blister formation, burning/tingling scalp and scalp severe acute irritant dermatitis, which is also known as scalp burn or cosmetic alopecia.^3–5 The four clinical entities are: acute (burn), sensory, non-immunologic contact urticaria (NICU) and cumulative. While scalp irritation also can be caused by contact with physical or biological agents, this column will discuss the irritation resulting from hair chemicals. The desire for a specific hairstyle or color can render the scalp exposed to different hair chemicals that may result to scalp irritation.

Scalp Severe Acute Irritant Dermatitis (Chemical Burn)

Common hair substances that may cause acute scalp irritation are relaxers and hair highlighting chemicals.^{4, 5} Acute scalp burn—because of the marked damage—deserves detailed investigation, and should be modeled in vitro. Relaxers are classified into two groups—lye, mostly sodium hydroxide; and no-lye, mostly guanidine hydroxide.5 According to the U.S. Food and Drug Administration (FDA), “Any relaxer can burn the scalp if used the wrong way.”6 However, lye-containing hair relaxers are known to cause more scalp burn than hair relaxers without lye. The adverse effects of relaxer exposure are contact dermatitis7 and hair breakage with alopecia, which may also include scarring.8, 9 (Additional information on relaxers is available in “Formula Anatomy Deciphered—Hair Relaxers and Straighteners” by Luigi Rigano, PhD, published in the November 2012 issue of Cosmetics & Toiletries.)

This is only an excerpt of the full article that appeared in Cosmetics & Toiletries, but you can purchase the full-text version.