Number sign. Not to be confused with the Chinese character äº, the sharp sign (â¯), the viewdata square (â), the numero sign (â), the equal and parallel to symbol (â) or the game Tic-tac-toe's grid. The symbol # is most commonly known as the number sign, hash, or pound sign.
The poison ivy rash is not contagious. When a person touches the poison ivy leaf, a substance on the surface of the leaf (a resin) rubs off. Over the next 48 to 72 hours the skin reacts to the resin by becoming red and developing bumps and blisters at and around the site where the resin was.
The rash caused by poison ivy, oak, and sumac is an allergic skin reaction to an oil called urushiol that is inside the plant. This oil is found in all parts of the plant, including the leaves, stems, roots, and berries. Poison ivy, oak, and sumac rash itself is not contagious. However, if oil remains on the skin or on clothing that came in contact with the plants, and the oil comes into further contact with skin, a rash may result.