An estimated 80% of adolescents and young adults will experience acne.1 The age range of occurrence has been expanding in recent years, starting at around 12 years as children enter puberty earlier, and may continue into a person’s 20s or even beyond.1 This pattern suggests that larger numbers of patients with acne will require treatment over longer periods of their lives. As no cure exists, dermatologists continue to explore the boundaries of the therapies that are available.

New Challenges to Topical Therapies

Topical therapies are usually the first medical line of defense against acne, and for the majority of patients, may be all that is needed — after good skin hygiene — to maintain clear skin. The goals of topical acne therapy are to eliminate the inflammatory and noninflammatory lesions on the surface of the skin and reduce permanent scarring and dyspigmentation, which can be accomplished with a number of current treatments.2

Topical acne treatments fall into two main categories: retinoids and antimicrobial therapies, both of which have typically been given as monotherapies for mild acne or in combinations for more severe forms of disease.1,2 In the current climate of expanding antimicrobial resistance, however, clinicians are becoming wary of using some of these agents as chronic treatments for acne.

The Most Commonly Used Topical Therapies

Retinoids used to treat acne include adapalene, isotretinoin, motretinide, retinoyle-ß-glucoronide, tazarotene, and tretinoin.1-3 Retinoids have both comedolytic and anticomedogenic actions to reduce the size of existing comedones and prevent the formation of new ones, and they may have anti-inflammatory activity as well.1,2 Because they help to normalize the disturbed environment of the epithelial layer by reversing differentiation and hyperproliferation, retinoids serve an additional function of priming the target area to facilitate absorption of topical antimicrobial agents.2

The most common adverse effects (AEs) are local skin irritation and photosensitivity. A review by Harris and Cooper3 pointed to a concern that when used topically, retinoids (with the probable exception of tretinoin) have teratogenic potential and should not be prescribed for women who are pregnant, breastfeeding, or who may become pregnant, although this has not been well studied.

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Antimicrobial agents include antibiotics, most commonly clindamycin or erythromycin. These drugs are inexpensive and have very few AEs. Because of the growing prevalence of antibiotic resistance, antibiotic monotherapy is no longer recommended for treatment of acne.2 The efficacy of erythromycin has been shown to wane over time, contributing to antibiotic resistance, while clindamycin maintains its effects.2 These antibiotics are especially safe and effective when used in combination with retinoids.

Benzoyl peroxide (BPO) is a topical antibacterial agent that is inexpensive to use and can be purchased over the counter. It is considered the strongest of the topical antimicrobial agents and is effective for mild to moderate acne.1,3 Because it is not an antibiotic, BPO does not produce antibiotic resistance. It works by causing peeling of the top layers of skin and may help with mild irritation.3 It is associated with AEs that limit its use for some patients, including skin irritation and dryness, burning or stinging sensations, erythema, and dermatitis.1-3 Peroxide also bleaches clothing and bedding, which is a major inconvenience to the use of BPO.2