Introduction

Salicylic acid (ortho-hydroxybenzoic acid) is a beta hydroxy acid agent (Fig 5.1), the properties and use of which were first described by Unna, a German dermatologist. It is a lipophilic compound which removes intercellular lipids that are covalently linked to the cornified envelope surrounding cornified epithelioid cells. Owing to its antihyperplastic effects on the epidermis, multiple studies document the beneficial effects of salicylic acid as a peeling agent. Salicylic acid has also been shown to have anti-inflammatory and antimicrobial properties. See Table 5.1.

Figure 5.1 Chemical structure of salicylic acid

Table 5.1 Differences between AHAs and BHAs

Patient Selection

Indications for salicylic acid peels include acne vulgaris (inflammatory and noninflammatory lesions), acne rosacea, melasma, postinflammatory hyperpigmentation (PIH), freckles, lentigines, mild to moderate photodamage, and texturally rough skin (Figs 5.2–5.4). Salicylic acid peels are well tolerated in all skin types (Fitzpatrick’s I to VI) and in all racial/ethnic groups. See Box 5.1.

Figure 5.2 Patient with texturally rough skin before (A) and after (B) a series of five salicylic acid peels

Figure 5.3 Patient with moderate melasma before (A) and after (B) a series of three salicylic acid peels and 4% hydroquinone

Figure 5.4 Patient with nodulocystic acne before (A) and after (B) a series of five salicylic acid peels

The efficacy of salicylic acid peeling has been assessed in several studies. Fifty percent salicylic acid ointment peeling was first used by Aronsohn to treat 81 patients who had freckles, pigmentation, and aging changes of the hands. He reported excellent results. Subsequently, other practitioners successfully used a 50% salicylic acid ointment paste, containing croton oil and buffered with methyl salicylate, for treatment of lentigines, pigmented keratoses and actinically damaged skin of the dorsal hands and forearms. After pretreatment with topical tretinoin and localized TCA 20%, the 50% salicylic acid paste was applied to the affected area and occluded for 48 hours. Following dressing removal, peeling and desquamation occurred and was relatively complete by the tenth day. Overall results were described as excellent. Despite these results, salicylic acid peeling did not move into the arena of popular peeling techniques until the mid 1990s. Kligman and Kligman ushered salicylic acid into the current arena of superficial peeling agents. They treated 50 women with mild to moderate photodamage, reporting improvement in pigmented lesions and surface roughness, and reduction in fine lines.

Grimes and colleagues reported substantial efficacy and minimal side effects in 25 patients treated with 20% and 30% salicylic acid peels in darker racial/ethnic groups. Conditions treated included acne vulgaris, melasma, and PIH. In addition, in a retrospective analysis of 90 patients treated by the author with salicylic acid peeling, 70% had significant improvement in acne and pigmentation, 25% had mild improvement, and 5% had minimal improvement.

Lee and colleagues treated 35 Korean patients with facial acne using 30% salicylic acid peels biweekly for 12 weeks. Both inflammatory and noninflammatory lesions were significantly improved. In general, the peel was well tolerated with few side effects. Given the aforementioned findings, there are several advantages and disadvantages of salicylic acid peeling (Table 5.2).

Table 5.2 Advantages and disadvantages of salicylic acid peeling