Alum powder is not available at Walgreens, according to its website, as of 2015. Alum powder is not an available product online nor in-store at Walgreens.
Alum powder is available from other online or retail stores such as Amazon and Herbs Direct. Alum powder can be purchased in bulk or in granulated form. The best place to purchase it may depend on its intended use.
Various forms of alum powder are used in several different applications. Potassium or ammonium alum is a chemical compound used as a crystal antiperspirant. Aluminum sulfate or potassium aluminum sulfate is used as an astringent while alum powder is used in the process of pickling or canning food to preserve fruit and vegetables' freshness.