(This blog post has been updated to make corrections to some of
the terminology originally used. A special thanks to Sandra J.
Baker, researcher and author of The Poison Oak & Poison Ivy
Survival Guide for her guidance.)
If you frequently experience exposure to poison ivy, oak or
sumac plants, then you may be familiar with the term for the
plants' oil called urushiol. Urushiol is an oily substance that is
found in all parts of poison ivy, oak and sumac plants including
leaves, stems and roots. Urushiol is in the plants' resin, so when
the canals break, the resin leaks out.
Did you know that a urushiol-like rash is not just created by
poison ivy, oak and sumac? You can react to other plants such
Mangos - the peels, leaves, stems and sap of
mango plants contain an allergenic oil called resorcinol. The
chemistry of resorcinol is similar to that of urushiol so if you
are allergic to poison ivy or oak, you may find you are allergic to
mangos. Mangos are the most common source of plant dermatitis in
Hawaii during its primary ripening season.
Cashews - the nut shells contain anacardiol and
cardol, which can cause an urushiol-like reaction. However,
roasting cashews will destroy the allergen. Cashews imported into
the United States are heated to neutralize the oils before they are
sold to you. Cashews labeled "raw" at your grocery store are in
Other sources of urushiol-like reactions include plants such as
the Rengas tree, Burmese lacquer tree, India marking nut tree and
Urushiol - The name comes from the Japanese word
Kiurushi which denotes a lacquer produced in East Asia
from the sap of Toxicodendron vernicifluum (the Lacquer
Tree) - Urushiol entry, Wikipedia.com
Why does urushiol cause a rash?
Contact with urushiol produces a rash in three out of four
people, although the severity of a rash will vary from person to
person. The rash caused by coming in contact with urushiol is the
body's natural reaction to the allergen which is why it is best to
remove it from your skin as soon as possible. Repeated contact with
urushiol can result in increased sensitivity to the oil.
The rash, also known as allergic contact dermatitis, can begin
as soon as a few hours after contact with urushiol or up to five
days later. Symptoms include itching, inflammation, oozing, and in
severe cases, a burning sensation.
How do I remove urushiol from my skin?
Washing with Tecnu
Original Outdoor Skin Cleanser or Tecnu Extreme Poison Ivy Scrub will
remove urushiol from your skin. In addition, Tecnu Extreme Poison
Ivy Scrub can help relieve itching caused by the rash.