Bismuth subgallate is primarily used in the medical and pharmaceutical fields for its astringent and protective properties. It is commonly found in over-the-counter medications for treating skin conditions such as minor burns, cuts, and irritations, where it helps to form a protective barrier over the affected area, promoting healing and reducing inflammation. Additionally, it is used in some gastrointestinal medications to alleviate symptoms of diarrhea and other digestive disorders, as it can help to soothe the lining of the stomach and intestines. Its mild antiseptic properties also make it useful in preventing infections in minor wounds.