CFR›Title 21›Chapter I›Part 331 ContainsSubparts A–DCorpusDaily eCFRDisplayed edition2026-04-15Last updated2026-04-15 PART 331—ANTACID PRODUCTS FOR OVER-THE-COUNTER (OTC) HUMAN USE Subparts A Subpart A—General Provisions Section 331.1 B Subpart B—Active Ingredients Sections 331.10–331.15 C Subpart C—Testing Procedures Sections 331.20–331.21 D Subpart D—Labeling Sections 331.30–331.80 Authority21 U.S.C. 321, 351, 352, 353, 355, 360, 371.Source39 FR 19874, June 4, 1974, unless otherwise noted. Previous 330 Part 330—Over-the-Counter (OTC) Human Drugs Which Are Generally Recognized as Safe and Effective and Not Misbranded Next 332 Part 332—Antiflatulent Products for Over-the-Counter Human Use