Supramolecular self-associating amphiphiles (SSAs) are a class of amphiphilic salt which have demonstrated antimicrobial activity against both Gram-positive and Gram-negative bacteria. Herein, we show that SSAs are also able to increase the efficacy of a range of currently used antimicrobial/therapeutic agents with a range of different chemical structures and modes of antimicrobial action against Gram-negative Escherichia coli, which include: octenidine (an antiseptic); ampicillin (an antibiotic); and cisplatin (a DNA chelating agent). Additionally, we show these effects to be dependent on the order of agent addition. Finally, through completion of a range of 1 : 1 SSA :  antimicrobial/therapeutic agent physicochemical studies we gain an understanding as to how the self-association events and resultant SSA aggregate structure are effected by the presence of these secondary molecular species.