Contact with the
poison ivy, oak, or sumac plants causes 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 these plants.
You may be more or less sensitive to the plants than other people. A
more sensitive person will have a more severe reaction and will react after
minimal contact with the oil.
The degree of sensitivity to poison ivy, oak, or sumac is affected
by:
- Physical activity. The urushiol may spread
during activity.
- How much contact you have had with the
plant.
- Age. Sensitivity may change with age. Young children are
less likely to have sensitivity to urushiol. Sensitivity peaks between ages 8
and 15. Some people, though, do not show a sensitivity to urushiol until middle
age.
- How well your
immune system functions.
| By | Healthwise Staff |
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| Primary Medical Reviewer | William H. Blahd, Jr., MD, FACEP - Emergency Medicine |
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| Specialist Medical Reviewer | H. Michael O'Connor, MD - Emergency Medicine |
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| Last Revised | August 30, 2011 |
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