The Poison-oak page

Poison-oak (Toxicodendron diversilobum) is very abundant on the Farm.   Before visiting, people should familiarize themselves with the growth form of the plant in order to avoid contact.   A simple brush against the leaves can cause a large reaction like the one below.   To the left there is a close up picture of the leaves, which occur in groups of three. The edge of the leaf is usually lobed, although, the shape can vary incredibly.   The texture of the leaf can vary also from thick and leathery in the sun to thin and papery in the shade.

The reaction is caused by an oil called urushiol.   The belief that eating the leaves or drinking a tincture can form an immunity is wrong. Only about 10-25% of the population will never react to urushiol.   The reaction is actually an immune system response to not only the urushiol, which by itself is small enough to go unnoticed by the immune system, but a combination of urushiol bonded to proteins in the skin cells.   Also, some people, who have not had much exposure to the plant, will be temporarily immune until the body has had time to

recognize the protein-oil combination as harmful (even though it is actually harmless).       The reaction will usually start 1-2 days after contact.   It will start out as a red area or scattered tiny blisters.   As it spreads is when the itching is the worst, and this can be expected happen for up to five days.   At this point, healing will start and, in a couple days, your skin should be back to normal.   There is no miracle cure yet, but some products seem to slow down the reaction.       As soon as possible after exposure, you should

attempt to remove the oils from your skin.   If you get to a water source within 10-15 minutes, a good scrubbing should do it.   After that help is needed.   Tecnu® works well to chemically unbind the oils from your proteins.   Anything, though, that removes oils from your skin, like rubbing alcohol or chlorine bleach, will be of help.   Some say these also help after the reaction has occurred to dry out the skin and the blistering, but caution should be taken to avoid burning the skin from overexposure.  Calamine lotion seems to help relieve the itching.

In short, unless you are lucky enough to be immune, the only way to prevent a reaction is to not touch the plant.   The only way to do this in the field on this farm is if a miracle occurs, but by knowing what the plant looks like, you can avoid excess contact.   By the way clothes can keep the oils in them, if unwashed, for up to a year, so you have to be careful even when you are out of the field. Below are some more pictures to aid your poison-oak expertise.

	Back to Plants Page
	Back to Shrubs Page

Back to Home