Calamine Powder is a mixture of zinc oxide (ZnO) with about 0.5% iron(III) oxide (Fe2O3). It is the main ingredient in calamine lotion and is used as an antipruritic (anti-itching agent) to treat mild pruritic conditions such as sunburn, eczema, rashes, poison ivy, chickenpox, and insect bites and stings.  

It is also used as a mild antiseptic to prevent infections that can be caused by scratching the affected area, and an astringent to dry weeping or oozing blisters and acne abscess. In a September 2, 2008 document the U.S. Food and Drug Administration recommended applying topical OTC skin protectants, such as calamine, to relieve the itch caused by poisonous plants such as poison ivy, poison oak, and poison sumac. Calamine has been found to be effective in treating acne and poison ivy.