Why does poison ivy always itch?

Answer by  CarolynOsborne (2804)

Allergens on the skin cause itchiness. Most people are allergic to poison ivy. A few lucky ones are not and they don't have any reaction to exposure.

Answer by  raun08 (1839)

The oils on the leaves of the plant are irritating to the skin of people who are 'allergic' to them. Some people do not react to exposure.

Answer by  RLozano (213)

Poison ivy, oak, and sumac plants all give off chemicals that are irritants. These irritants are extremely effective at causing itches, a tiny trace will cause a problem. When you touch poison ivy an oil is absorbed into the skin. This causes irratation in a sensitive person until the chemical is gone. Calumine and hot soapy showers are common treatments.

Answer by  Isidro (624)

This happens because the plant is a bacterial carrying machine and this can be caused by the plants fuzzy outer layer. Also it is because they are designed to do this.