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Benzoyl peroxide 5% plus erythromycin 3% (Benzamycin. gel, Dermik) has been available in the USA since 1984, in the UK since 1995, and was approved in Canada recently. Benzoyl peroxide has been available since the 1960s and topical antibiotics have been used since the 1970s. Combinations of antiacne medications have been utilized by practitioners searching for treatment that improves compliance, so it is hardly surprising that erythromycin and benzoyl peroxide are now available combined in a gel preparation.

Key Words:
Acne, Erythromycin, Benzoyl peroxide, Benzamycin


Benzamycin® is indicated for the topical treatment of moderate acne vulgaris characterized by comedones, inflammatory papules/pustules with or without an occasional cyst or nodule. It is not indicated for cystic acne.

Clinical Studies

In double-blind studies, the combined preparation was significantly more effective against inflammatory lesions than erythromycin or benzoyl peroxide used alone.1,2

Benzamycin® has been shown to be more effective than clindamycin phosphate solution3 and clindamycin phosphate lotion.4 There are no studies comparing Benzamycin® with benzoyl peroxide and erythromycin prescribed separately.

Bacterial Resistance

Use of topical preparations of antibiotics selects for antibiotic-resistant bacteria because of the gradient of drug concentration present at the periphery of the treated area.6 Propionibacteria highly resistant to erythromycin5 are found on the skin of 25% of antibiotictreated acne patients.6 Strains resistant to erythromycin usually exhibit some cross resistance to clindamycin. The combination of erythromycin and benzoyl peroxide is said to be safer because it does not promote the overgrowth of erythromycin-resistant coagulase-negative staphylococci that occurs when erythromycin is used alone.6 In a recently published study, the combination of 5% benzoyl peroxide and 3% erythromycin had greater in vivo antiproprionibacterial activity than 3% erythromycin alone, and brought about significant clinical improvement in acne patients with high numbers of erythromycin-resistant proprionibacterial strains pre-treatment.6

Side Effects

Benzoyl peroxide used alone is usually more irritating than topical antibiotics, causing erythema and scaling sometimes accompanied by transient burning and/or itching.7 However, in a cumulative irritation test, the combination product was significantly less irritating than benzoyl peroxide alone.8 The reduced irritancy has been attributed to the anti-inflammatory effect of the erythromycin. The Benzamycin® gel can cause some erythema, burning, and itching at first, but this usually subsides despite continued treatment.9 Affected patients can try using less gel or applying it only once daily until the irritation subsides. Moisturizers can be used to counteract any dryness or scaling.9 The benzoyl peroxide can bleach hair or coloured fabrics.

Safety During Pregnancy & Lactation

The safety of Benzamycin® in pregnant or breast-feeding patients is unknown but seems unlikely to be a problem, as even when administered systemically, erythromycin is not known to be harmful to pregnant patients and is only excreted in small amounts in breast-milk.


A thin layer of Benzamycin® should be applied to affected areas twice daily. Areas to be treated should first be washed thoroughly with a non-medicated soap, rinsed with warm water, and gently patted dry.

Clinical Assessment

Benzamycin® gel is a stable formulation of benzoyl peroxide 5% and erythromycin 3%, which is useful in the treatment of Acne vulgaris and has a low potential for producing resistant organisms. Although it is not known how effective it is compared with the two drugs prescribed separately, Benzamycin® is simpler to use and likely to improve patient compliance. It is not as irritating as benzoyl peroxide used alone. Daily costs of using Benzamycin® are similar to the cost of using other commonly prescribed anti-acne combinations.


  1. Shalita AR, Chalker DK, Ellis CN, et al. A multi-center, double-blind, controlled study of the combination of erythromycin/benzoyl peroxide, erythromycin alone, and benzoyl peroxide alone in the treatment of acne vulgaris. Cutis 1992; 49(6A): 1-4.
  2. Chalker DK, Shalita A, Smith JG, et al. A double-blind study of the effectiveness of a 3% erythromycin and 5% benzoyl peroxide combination in the treatment of acne vulgaris. J Am Acad Dermatol 1983; 9: 933-936.
  3. Mills OH, Berger RS. Comparison of the combination of erythromycin/benzoyl peroxide topical gel to clindamycin phosphate solution in treatment of acne vulgaris. Cutis 1992; 49: 5-7.
  4. Packman AM, Brown RH, Dunlap FE, et al. Treatment of acne vulgaris: combination of 3% erythromycin and 5% benzoyl peroxide in a gel compared to clindamycin phosphate lotion. Internat J Dermatol 1996; 35: 209-211.
  5. Bojar RA, Eady EA, Jones CE, et al. Inhibition of erythromycin-resistant proprionibacteria on the skin of acne patients by topical erythromycin with and without zinc. Br J Dermatol 1994; 130: 329-336.
  6. Eady EE, Bojar RA, Jones, CE et al. The effects of acne treatment with a combination of benzoyl peroxide and erythromycin on skin carriage of erythromycin-resistant proprionibacteria. Br J Dermatol 1996; 134: 107-113.
  7. Leyden JJ. Open-label evaluation of topical antimicrobial and anti-acne preparations for effectiveness versus Proprionibacterium acnes in vivo. Cutis 1992; 49: 8-11.
  8. Leyden JJ. An assessment of cumulative irritation associated with a combination of topical erythromycin and benzoyl peroxide. Cutis 1992; 49: 20-22.
  9. Benzamycin gel for acne. Drug Therap Bull 1995; 33: 62-64.