Compositions including a complex of fatty acids (e.g., including one or more C4 to C40 fatty acids, such as a C4 to C20 fatty acid) and one or more amino acids (and particularly one or more amino acids having electrically charged basic side chains, e.g., Arginine, Lysine, etc.) for use as an anti-pathogenic composition. These compositions may include the complex of fatty acid:amino acid having a lamellar supramolecular structure. In particular, described herein are therapeutic compositions of undecylenic acid:Arginine forming a complex of undecylenic acid and Arginine.