Plant Image Collection
Poison Ivy Berries Poison Sumac
Poison Ivy Vines Poison Sumac Ginkgo biloba
Mango: A cause
of dermatitis in Hawaii Cashews & Oils
during harvest season.
Japanese Lacquer Tree Brazilian Pepper Tree
(can cross-react with others)
Plants NOT RELATED to Poison Oak/Ivy that cause rash
Hyacinth: Lilaceae
Irritant: Calcium Oxalate
Asteraceae: Chrysanthemum, Ragweed, and Pyrethrum
Sensitizer: Sesquiterpine lactone
Mustard: Brassicaceae
Irritant: Thiocyanate
Poinsettia: Euphorbiaceae
Irritants: Phorbol esters & latex
Daffodil: Narcissus
Irritant: Calcium Oxalate
Ease the Sting of Poison Ivy
Article reprinted from New York Times by Jane E. Brody
You can get it mowing the lawn, whacking weeds, petting the dog, hiking through the woods, burning logs in a fireplace, gardening, retrieving a lost ball, using the great outdoors for a toilet, putting clothes in the washing machine or removing your shoes. ''It'' is poison ivy, a source of misery for half the people who make contact with its allergenic sap and a potential problem for many more people who are not yet sensitized.
As you can see from the above list of possible exposures, poison ivy dermatitis is not so easy to avoid. However, prevention is possible, and when that fails, quick recognition of an incipient outbreak and appropriate action can greatly reduce its severity and resulting discomfort. Unfortunately, myths and misconceptions about this perennial problem abound and all too often result in extensive outbreaks that require medical attention.
No one is immune. Even if you have never reacted to poison ivy, a single intense exposure can cause a miserable rash or repeated lesser exposures can trigger a sensitivity that will render you susceptible to attacks for the rest of your life. So everyone would be wise to learn more about the plant and how to avoid being exposed.
Poison ivy and its companions in crime, poison oak and poison sumac, share a telling genus name, Toxicodendron, and a sap that contains urushiol.
Urushiol is an oil that rapidly penetrates the skin and combines with skin proteins, triggering an allergic reaction in those already sensitive to it and priming the pump for a future allergic reaction in those not yet sensitive.
Urushiol is found in all parts of the plant -- leaves, stems, roots, flowers and berries -- and is readily released when the plant is bruised in some way, as when a hiker's leg brushes against it or a child's ball lands on it, when it is cut down by a mower or when it is burned in a fire. As some mango lovers have discovered, urushiol (in lower concentrations, fortunately) is also found in the skin of mangoes, as well as in the fleshy shell of cashews and ginkgo nuts.
The sap is hardy; even in the dead of winter it can cause a reaction. It can also survive for long periods on contaminated clothing, gardening tools and sports equipment. Items contaminated in the fall may cause a reaction when handled the next spring. Even dead, the plant is a problem. Poison ivy leaves or stems twined around logs can spew urushiol into the air when burned and cause an internal reaction when inhaled. A pet can carry the toxin on its fur and transfer it to you or the furniture you sit on.
Though the axiom ''leaves of three, let them be'' is well known, poison ivy and poison oak may have five leaves and poison sumac, a tall shrub, has seven to 13 leaflets on each stem.
Furthermore, the shape of these leaves and the growth habits of the plants are highly variable, especially in different regions of the country. The plants can be low-growing or form bushes or vines. Poison ivy vines were once deliberately grown as foliage on English buildings for the striking red color they turn in fall. One aid in recognizing poison ivy and its relatives is to look for black spots on the plant, an indication that urushiol, which is normally yellowish, has been exposed to air, perhaps by the chomp of an insect.
An allergic reaction to urushiol typically becomes noticeable 24 to 36 hours after exposure, although it can begin as soon as 6 hours later, according to a report in the May 15 issue of Patient Care, an educational magazine for doctors.
An itchy, red, blistering rash occurs wherever urushiol has directly touched the skin and only there. It is a myth that the rash is contagious or that it can be spread elsewhere on the body through the fluid in blisters.
However, different parts of the body may break out at different times for one of two reasons: because the skin in different places is exposed at different times, for example, by later contact with contaminated clothing, or because skin that is thin absorbs urushiol faster than thicker skin.
From the California State Compensation Insurance Fund's website
Thousands of California workers seek medical treatment for poison oak dermatitis every year. While some individuals are less susceptible than others, no one is completely immune. There are some simple things you can do to prevent or minimize the unpleasant often-disabling effects of poison oak exposure. Learn to recognize, avoid, and prevent exposure, and get rid of it when possible.
Recognize - The poison oak leaf looks like a miniature oak leaf, a
triple leaf pattern leading off one stem with prominent veins and a
shiny surface. In some regions the leaves remain green during the entire
time they are on the stem. In other areas the leaves change to various
colors with the changing seasons. After the leaves fall off, the bare
wood is also dangerous and so are the roots. It can grow in the form of
vines, trailing shrubs, or upright woody shrubs. It may flourish in the
deep woods where soil moisture is plentiful or it may be found in very
dry soil on the most exposed hillsides.
Avoid - Stay away from any vegetation that you suspect may be poison oak. Avoid contact with anything that touched it, whether animal, clothing or tools.
Prevent - Sometimes you have to enter or work in areas where there is poison oak. When this is necessary, certain precautions can be taken:
- Wear protective clothing such as long-sleeved shirts, long pants tied around the ankles, leather gloves with gauntlets and neckerchiefs.
- Several protective creams are available which form barriers to protect against the toxic oil found in all parts of the plant. There are also injections or tablets that provide protection for some people.
- When removing clothing, take shoes off first and leave them outside for decontamination by washing.
- Remove all clothing and wash it separately.
- Any object you touch after having been exposed to poison oak can act as a carrier to contaminate others.
- If you come in contact with poison oak, wash immediately or take a shower, not a bath, using strong soap or detergent.
- When dressing, put shoes on last so that any poisonous substance remaining on shoes does not contaminate the inside of trousers.
- For severe inflammation and itching, consult a physician.
No part of the plant should ever be eaten. It is a violent irritant and poisonous. It should never be destroyed by burning. Inhalation of the smoke can be catastrophic. Destroy poison oak by using an approved vegetation spray to eradicate it.
