Poison Ivy,Oak,or Sumac - Cause
poison ivy, oak, or sumac plants can cause a rash
(allergic contact dermatitis ). The rash is caused by contact
with the oil (urushiol) in these plants. Urushiol is an
allergen, so the rash is actually an
allergic reaction to the oil in poison ivy, oak, or
- The leaves, stems, vines, twigs, berries, and
roots of these three plants contain urushiol, even after they have
- Urushiol is a colorless, odorless, sticky oil that is easily
spread before a rash develops.
- The rash can also occur after
indirect contact with this oil. This may happen when
you touch clothing, pet fur, sporting gear, gardening tools, or other objects
that have come in contact with one of these plants.
No one is born allergic to any of these plants. You become
allergic to them through contact with them (or with
other plants). After you have been in contact with one
of the plants one or more times, your body's immune system may recognize
urushiol as an allergen and you may have an allergic reaction. You may be
more or less sensitive than other people to the plants. A more sensitive
person will react after contact with only a small amount of urushiol and have a
more severe reaction.