These are direct quotes for your convenience from the websites
According to the Wall Street Journal...
indicates that poison ivy has gotten MUCH nastier since the 1950's. Leaf
size and nasty oil content are way up.
Approximately 85 percent of the population will develop an allergic
reaction if exposed to poison ivy, oak or sumac, according to the American
Academy of Dermatology. Nearly one-third of forestry workers and
firefighters who battle forest fires in California, Oregon and Washington
develop rashes or lung irritations from contact with poison oak, which is
the most common of the three in those states.
The cause of the rash, blisters, and infamous itch is urushiol
(pronounced oo-roo-shee-ohl), a chemical in the sap of poison
ivy, oak and sumac plants. Because urushiol is inside the plant, brushing
against an intact plant will not cause a reaction. But undamaged plants are
Reactions, treatments and preventive measures are the same for all three
poison plants. Avoiding direct contact with the plants reduces the risk but
doesn't guarantee against a reaction. Urushiol can stick to pets, garden
tools, balls, or anything it comes in contact with. If the urushiol isn't
washed off those objects or animals, just touching them--for example,
picking up a ball or petting a dog--could cause a reaction in a susceptible
person. (Animals, except for a few higher primates, are not sensitive to
Urushiol that's rubbed off the plants onto other things can remain potent
for years, depending on the environment. If the contaminated object is in a
dry environment, the potency of the urushiol can last for decades, says
Epstein. Even if the environment is warm and moist, the urushiol could still
cause a reaction a year later.
If you've been exposed to poison ivy, oak or sumac, if possible, stay
outdoors until you complete the first two steps:
- First, Epstein says, cleanse exposed skin with generous amounts of
isopropyl (rubbing) alcohol. (Don't return to the woods or yard the same
day. Alcohol removes your skin's protection along with the urushiol and
any new contact will cause the urushiol to penetrate twice as fast.)
- Second, wash skin with water. (Water temperature does not matter; if
you're outside, it's likely only cold water will be available.)
- Third, take a regular shower with soap and warm water. Do not use soap
before this point because "soap will tend to pick up some of the urushiol
from the surface of the skin and move it around," says Epstein.
- Clothes, shoes, tools, and anything else that may have been in contact
with the urushiol should be wiped off with alcohol and water. Be sure to
wear gloves or otherwise cover your hands while doing this and then
discard the hand covering.
Dealing with the Rash
If you don't cleanse quickly enough, or your skin is so sensitive that
cleansing didn't help, redness and swelling will appear in about 12 to 48
hours. Blisters and itching will follow. For those rare people who react
after their very first exposure, the rash appears after seven to 10 days.
Because they don't contain urushiol, the oozing blisters are
contagious nor can the fluid cause further spread on the affected person's
body. Nevertheless, Epstein advises against scratching the blisters because
fingernails may carry germs that could cause an infection.
The rash will only occur where urushiol has touched the skin; it doesn't
spread throughout the body. However, the rash may seem to spread if it
appears over time instead of all at once. This is either because the
urushiol is absorbed at different rates in different parts of the body or
because of repeated exposure to contaminated objects or urushiol trapped
under the fingernails.
The rash, blisters and itch normally disappear in 14 to 20 days without
any treatment. But few can handle the itch without some relief. For mild
cases, wet compresses or soaking in cool water may be effective. Oral
antihistamines can also relieve itching.
FDA also considers over-the-counter topical corticosteroids (commonly
called hydrocortisones under brand names such as Cortaid and Lanacort) safe
and effective for temporary relief of itching associated with poison ivy.
For severe cases, prescription topical corticosteroid drugs can halt the
reaction, but only if treatment begins within a few hours of exposure.
"After the blisters form, the [topical] steroid isn't going to do much,"
says Epstein. The American Academy of Dermatology recommends that people who
have had severe reactions in the past should contact a dermatologist as soon
as possible after a new exposure.
Severe reactions can be treated with prescription oral corticosteroids.
Phillip M. Williford, M.D., assistant professor of dermatology, Wake Forest
University, prescribes oral corticosteroids if the rash is on the face,
genitals, or covers more than 30 percent of the body. The drug must be taken
for at least 14 days, and preferably over a three-week period, says FDA's Ko.
Shorter courses of treatment, he warns, will cause a rebound with an even
more severe rash.
There are a number of OTC products to help dry up the oozing blisters,
- aluminum acetate (Burrows solution)
- baking soda
- Aveeno (oatmeal bath)
- aluminum hydroxide gel
- zinc acetate
- zinc carbonate
- zinc oxide
The oozing fluids released by itching blisters do not spread the poison.
The appearance of a spreading rash indicates that some areas received more
of the poison and reacted sooner than other areas. The blisters and oozing
result from blood vessels that develop gaps and leak fluid through the skin;
if the skin is cooled, the vessels constrict and leak less. If poison ivy is
burned and the smoke then inhaled, this rash will appear on the lining of
the lungs, causing extreme pain and possibly fatal respiratory difficulty.
If poison ivy is eaten, the digestive tract, airway, kidneys or other organs
can be damaged.
Understanding why new lesions may develop for two weeks (studied on
forearm) after one exposure was made clear by a University of Miami
scientist: larger amounts have earliest onset and largest reaction, smallest
produce a delayed reaction. The overall severity 'progresses' with the
combined active lesions. Therefore, the last new lesion should occur at two
weeks after last exposure, the total rash (untreated) may go on for 3-4
Urushiol oil can remain active for several years, so handling dead leaves
or vines can cause a reaction. In addition, oil transferred from the plant
to other objects (such as pet fur) can cause the rash if it comes into
contact with the skin.
People who are sensitive to poison-ivy can also experience a similar rash
mangoes. Mangoes are in the same family (Anacardiaceae)
as poison ivy; the sap of the mango tree and skin of mangoes has a chemical
compound similar to urushiol.
Similar reactions have been reported occasionally from contact with the
related aromatic sumac or Japanese lacquer tree.
*Do not burn ivy. The oil can become airborne and go into your lungs. This a
problem for firefighters during a forest fire and another good reason for
their breathing equipment.
Confusion with other plants
- Boxelder Maple (Acer
negundo) saplings can look almost indistinguishable from poison
ivy. While Boxelder Maples often have five or seven leaflets, three
leaflets are also common. The two can be differentiated by the fact that
Poison-ivy has alternate leaves, while the maple has opposite leaves; in
other words, by observing where the leaf stalk (the "branch" the three
leaflets are attached to) meets the main branch. Another leaf stalk
directly on the opposite side is characteristic of Boxelder Maple. If the
three-leaflet leaves alternate along the main branch, it may be
Virginia creeper (Parthenocissus quinquefolia) vines can look
like Poison-ivy. The younger leaves can consist of three leaflets but have
a few more serrations along the leaf edge, and the leaf surface is
somewhat wrinkled. Most Virginia creeper leaves have five leaflets,
however. Virginia creeper and poison ivy very often grow together, even on
the same tree. Beware that some people are allergic to the oxalate
crystals that are in its sap, even people who do not get poison ivy.
Western Poison-oak (Toxicodendron diversilobum) leaflets also
come in threes on the end of a stem, but each leaflet is shaped somewhat
like an oak
leaf. Western Poison-oak only grows in the western United States and
Canada, although many people will refer to poison ivy as poison-oak. This
is because poison ivy will grow in either the ivy-like form or the brushy
oak-like form depending on the moisture and brightness of its environment.
The ivy form likes shady areas with only a little sun, tends to climb the
trunks of trees, and can spread rapidly along the ground.
Poison Sumac (Toxicodendron vernix) has compound leaves with
7–15 leaflets. Poison sumac never has only three leaflets.
lobata) is a non-toxic edible vine that scrambles extensively over
lower vegetation or grows high into trees. Kudzu is an
invasive species in the southern United States. Like poison ivy it has
three leaflets, but the leaflets are bigger than those of poison ivy and
are pubescent underneath with hairy margins.
raspberry vines bear a passing resemblance to poison ivy, with which
they may share territory. The chief difference between blackberry vines
and poison ivy is that blackberry vines have spines on them, whereas
poison ivy is smooth. Also, the three-leaflet pattern of blackberry vine
leaves changes as the plant grows: the two bottom leaves both split into
two leaves, for a total of five in a cluster. They have many teeth along
the leaf edge, and the top surface of their leaves is very wrinkled where
the veins are, and the bottom of the leaves is light minty - greenish
white, while poison ivy is all green. The stem and vine of poison ivy are
brown and woody, while blackberry stems are green with thorns.
- The thick vines of
grape, with no rootlets visible, differ from the vines of poison ivy,
which have so many rootlets that the stem going up a tree looks furry.