I.C. Ivy Block was formulated to protect against poison ivy, poison oak, and poison sumac rash. This easy to apply lotion has four modes of protection against urushiol oils. The bentonite clay helps absorb the urushiol, while zinc acetate will dry it out. A film former that will close the pores from absorbing the oils and finally, witch hazel that can stop irritation from starting. When using this product simply apply it like sunscreen to any exposed skin at least 15 minutes before entering an area that may have poisonous plants. Repeated use is recommended and reapply at least every 4 hours.