Bismuth subgallate is a yellow substance that presents as an unscented powder. When exposed to sunlight, it becomes discolored. This drug is a heavy metal salt of gallic acid that is insoluble and ineffectively absorbed. It acts to protect the gastric mucosa and has potent astringent, antimicrobial and hemostatic effects. Bismuth subgallate is available as an over-the-counter antiperspirant where it is usually utilized as a major component.