Can erythromycin topical 2% and retin-a micro be used in the same day? say one in the am and one in the pm for acne?

Acne: Yes, one is typicaly recomended to use in the morning and the other at night, both should be used in small amounts after washing your face.

Yes: You certainly can use this combination. Erythromycin in the am and retina-a micro at night would be the best plan. However, i rarely use erythromycin. Its just not that effective for most people. Clindamycin doesn't cost any more, and is usually much more effective, especially when it is combined with a small amount of benzoyl peroxide.