So who (or, what) is the culprit behind the spread of poison ivy
rash? A highly concentrated, invisible oil called, urushiol.
Urushiol, is the rash-causing oil found in all parts of poison ivy,
poison oak, and poison sumac plants. Approximately 85% of the
population experiences an allergic reaction to these noxious
plants, and according to the National Institute of Occupational
Health & Safety, 50 micrograms of urushiol is enough to cause a
rash in 80-90% of adults. That is less than one grain of table
Contact with urushiol can happen in two ways. The first, direct
contact with any part of the plant. Poison ivy plants and poison
oak plants can be hard to identify as they can grow in several
forms. These noxious plants have been known to grow as bushes,
ground cover, and creeping vines. Often times, a person comes into
contact with them, and doesn't even know it. The second way to come
into contact with urushiol is through secondary contamination, or
indirect contact. Urushiol can last on inanimate objects for a
period of months, even years, as it does not evaporate. Therefore,
the next time you come into contact with one of these items, you
could possibly develop a rash.
In many cases, after coming into contact with urushiol oil and
once the initial breakout has occurred, new spots will appear a day
or two (or, more) later. This leads many to believe that the rash
is "spreading." However, this may be due to absorption. Because
some areas of the body have thicker skin than others, urushiol can
be absorbed at a slower rate than areas of the body where the skin
is thinner. Therefore, rashes in areas with thicker skin may not
appear right away.
How Spreading Occurs
If the oil is not properly removed with a cleanser specifically
designed for poison oak and poison ivy (such as Tecnu®), urushiol
can remain on the surface of the skin and continue to spread to
other areas of the body. Typically, urushiol is absorbed within the
first 8 hours after exposure, although this can vary. Surprising to
many, the liquid that oozes from the blisters of a poison ivy rash
does not spread the oil. By the time blisters form, your body has
already absorbed the urushiol.
After coming into contact with these poison plants, showering
rather than taking a bath is always recommended. As soothing as a
nice, hot bath may sound, it can potentially make your rash worse.
Upon submerging yourself in water, there is a chance that the
urushiol on your skin can lift, and settle on top of the water,
giving the urushiol a chance to spread to other areas of your body.
Now, after the first shower using a cleanser such as Tecnu®, it is
OK to follow up with a bath should you choose.
It is never recommended to take a hot shower immediately after
exposure to poison ivy or oak. The reason being, hot water opens
yours pores. If urushiol is on the surface of the skin, and the
pores open up, more urushiol stands a chance of being absorbed into
your system. For that reason, showering with cool or lukewarm water
for the first shower after exposure is best. With the initial
shower, we recommend using a cleanser designed to remove urushiol
such as Tecnu® or Tecnu Extreme®.
Subsequent showers can be taken with hot water.