Font Size

Sensitivity to Poison Ivy, Oak, or Sumac

Sensitivity to Poison Ivy, Oak, or Sumac

Contact with the poison ivy, oak, or sumac plants causes a rash (allergic contact dermatitisClick here to see an illustration.). 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.


ByHealthwise Staff
Primary Medical ReviewerWilliam H. Blahd, Jr., MD, FACEP - Emergency Medicine
Specialist Medical ReviewerH. Michael O'Connor, MD - Emergency Medicine
Last RevisedAugust 30, 2011

eMedicineHealth Medical Reference from Healthwise

This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

To learn more visit

© 1995-2012 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.

Medical Dictionary