If your skin doesn’t respond to benzoyl peroxide in the various over-the-counter higher strengths or in combination with a well-formulated BHA (salicylic acid), the next step is a prescription topical antibacterial, meaning some type of antibiotic, in a liquid, lotion, or gel form. Topical antibiotics have limitations. They can have difficulty penetrating the hair follicle, and long-term use can lead to antibiotic-resistant strains of bacteria. Erythromycin, tetracycline, and clindamycin are the most popular topical antibiotics.
You can use these antibiotics alone, but a good deal of research points to the greater benefit of combining these with benzoyl peroxide to create a potent and effective treatment. Studies indicate that when topical clindamycin or erythromycin are combined with benzoyl peroxide, both have demonstrated clinical efficacy in the treatment of acne. When used in tandem, they promise greater efficacy than either individual agent alone, through their antibacterial and anti-inflammatory complementary effects. Together they have an earlier onset of action, are significantly more effective against inflamed and total lesions, and are better tolerated, which should improve usage. (Sources: Dermatology Clinics, January 2009, pages 25-31; British Journal of Dermatology, January 2008, pages 122-129; Journal of Cutaneous Medical Surgery, January 2001, pages 37-42; and American Journal of Clinical Dermatology, 2001, volume 2, issue 4, pages 263-266.)
Warning: Do not apply benzoyl peroxide and a retinoid (such as Retin-A, Renova, Tazorac, Avita, generic tretinoin) at the same time. Benzoyl peroxide inactivates retinoids (Source: British Journal of Dermatology, September 1998, page 8). The exception to this is Differin (adapalene), which is compatible with benzoyl peroxide.