[Code of Federal Regulations] [Title 21, Volume 5] [Revised as of April 1, 2008] From the U.S. Government Printing Office via GPO Access [CITE: 21CFR333.310] [Page 229] TITLE 21--FOOD AND DRUGS CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF PART 333_TOPICAL ANTIMICROBIAL DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE--Table of Contents Subpart D_Topical Acne Drug Products Sec. 333.310 Acne active ingredients. The active ingredient of the product consists of any of the following when labeled according to Sec. 333.350. (a) Resorcinol 2 percent when combined in accordance with Sec. 333.320(a). (b) Resorcinol monoacetate 3 percent when combined in accordance with Sec. 333.320(b). (c) Salicylic acid 0.5 to 2 percent. (d) Sulfur 3 to 10 percent. (e) Sulfur 3 to 8 percent when combined in accordance with Sec. 333.320.