Benzoyl peroxide (BPO) was introduced in the treatment of
acne in 1934. Despite the fact that only few randomized trials have been published, BPO is considered the standard in topical
acne treatment. Anaerobic bacteria are reduced by oxidative mechanisms and the induction of resistant strains is reduced. Topical formulations are available at concentrations of 2.5, 5, 10 and 20 %. The effect is dose-dependent, but the irritation increases with higher concentrations. Usually 5 % BPO is sufficient to control
acne grade I-II. Due to its strong oxidative potential, patients should be advised that BPO may bleach colored and dark clothing, bedding and even hair. BPO is safe for use in pregnant and lactating females because it is degraded to
benzoic acid. It is a cost-effective treatment for
acne grade I-II. Patients with papulopustular
acne grade I-II, particularly with marked
inflammation, show satisfactory improvement with topical
antibiotic treatment. The following compounds are available and effective:
erythromycin,
clindamycin and
tetracycline (the latter being less frequently used). A review in 1990 suggested that topical
tetracycline was ineffective in the treatment of
acne. Along with eliminating Propionibacterium acnes, the main mechanism of topical
antibiotics is their antiinflammatory effect. All three penetrate the epidermal barrier well and are similarly efficacious. Randomized trials have shown that in concentrations of 2-4 %, their effects are comparable to oral
tetracycline and
minocycline. Combination
therapy with
retinoids or
benzoyl peroxide (BPO) increases efficacy.
Retinoids increase penetration and reduce comedones, while topical
antibiotics primarily address
inflammation. One side effect of topical antibacterial treatment is an increase in
drug-resistant resident skin flora with gram-negative microorganisms prevailing, which can lead to gram-negative
folliculitis. All three
antibiotics fluoresce under black light which may produce interesting effects in a discotheque. There are two reports of topical
clindamycin causing
pseudomembranous colitis after long-term and widespread usage.
Azelaic acid has a predominant antibacterial action, although it is not considered as an
antibiotic in the classical sense. Furthermore, it possesses a modest comedolytic effect. Burning upon application is common. Since
azelaic acid is naturally present, systemic side effects are not likely to occur, making it safe for
acne treatment during pregnancy and lactation.