Poison Ivy,Oak,or Sumac - Exams and Tests
A rash (allergic
contact dermatitis ) from
poison ivy, oak, or sumac plants usually is diagnosed
through a physical exam and questions about your outdoor activities.
Your doctor will examine the rash to decide which kind of plant
caused it and ask about:
- The length of time between possible exposure
and development of the rash.
- The length of time you were out in the
- What you were doing when the exposure may have occurred
(hiking, for example).
- Other rashes you have had.
job and your hobbies.
Diagnosis is harder when there are no clues that you have
been in contact with the plant. Sometimes
indirect contact with the plant oil (urushiol) causes
the rash. Urushiol that is on clothing or other objects may spread to your skin
months after initial contact. If a bacterial infection is suspected, your
doctor may take a sample of blister fluid for a
If your primary care doctor is
not sure of the cause, you may need to see a
dermatologist for a direct patch skin test. In this
test, small amounts of allergens are placed on the skin and covered with a
bandage for several days. The patch is then removed and the skin is examined for