Poison Ivy Myths

Just as tenacious and irrational myths surround bats and snakes, many folk beliefs surround poison ivy and its effect on sensitive individuals. These misunderstandings are often deeply held and difficult to change because they're passed along family lines where the "teacher" is considered a credible source of information. When a youngster begins by saying, "My daddy says..." you know you're on difficult and tricky ground. By the time the youngster reaches adulthood, many of these misbeliefs are bolstered by further misinterpretations of experiences the individual has had with this common plant.

Spring is an excellent time to "touch" on this subject of poison ivy for two reasons. First, a fundamental strategy for protecting yourself and youngsters from the effects of poison ivy it to simply avoid it, and that means you have to become familiar with it in all its forms. The plant flowers in May, and many young shoots are just beginning to leaf out for the summer. Talking about poison ivy also provides an opportunity to compare ideas supported by facts with beliefs not supported by facts but accepted simply because they came from a "credible" source.

Popular Poison Ivy Myths

Myth 1. Poison oak causes more blisters while poison ivy causes a milder skin rash.

False. many people believe poison oak causes a more severe rash and even identify the plant by the severity of the rash. Actually, there are three closely-related plants that cause similar poisoning effects.

a. Poison oak doesn't occur in Pennsylvania. Look for it to the south and west of our state. It's a shrubby plant and the leaves are much more hairy than our poison ivy.

b. Poison sumac is an obligate wetland plant. Unless your backyard is a swamp, don't expect to find poison sumac there. (Incidentally, there are five other species of sumac, all with red berries, that are not poisonous. Several of these are common trees of disturbed areas.)

c. That leaves poison ivy. It's common, widespread, and the culprit for most all cases of contact dermatitis. Many folks will not easily accept only one kind of poison ivy because they "know" they've had poison oak or poison sumac in their yard. This myth is tough to change.

Actually, part of the reason for this misconception is that poison ivy occurs in several forms. It can grow as a shrub, a creeping vine, or spread over the ground by rhizomes. Some leaves are more obviously toothed than others which leads some folks to believe the toothed form is poison oak.

All forms of poison ivy have compound leaves, arranged alternately on the stem, with three leaflets. The stem of the center (terminal) leaflet is longer than the stems of the other two.

Myth 2. If you eat poison ivy, you'll be protected from it in the future.

False. It's difficult to imagine how such a dangerous myth became so widespread. Eating poison ivy can result in a serious reaction and can even be fatal. Still, every year, students repeat this myth beginning, "My uncle says..." or "My Papaw says..."

Myth 3. Fluid from blisters can spread the rash to other body areas.

False. This is a tough myth to dispel because scratching the red area appears to spread the rash to other areas. Actually, the reaction develops over a period of time - usually taking hours or days to occur. The occurrence of a new rash, say further up the arm, doesn't mean the rash was spread but that that area was slower to respond to the poisonous oil.

Once the oil triggers the reaction, our own bodies release defensive chemicals that cause the redness, itching, and blistering. The blister fluid doesn't come from the plant at all but is produced by our own
body.

Myth 4. Poison ivy enters the blood stream and can be carried to other parts of the body where it can outbreak later.

False. Poison ivy rash is caused by contact with an oil (uroshiol) from the poison ivy plant. The oil attaches to the outer horny skin cells and the layer of living cells below. Washing with soap and water to remove the oil is an effective control, but such washing normally has to be done within minutes to avoid any rash at all. In addition, washing must be far more thorough than we normally wash our hands in order to be effective.

Outbreaks on other body areas means the oil was transferred to that area from another body part, by articles of clothing, tools, or pets that held the same oil. Remember, it's the contact with the uroshiol oil that causes the reaction. This oil is essentially nonvolatile and can remain on articles and clothing for as much as a year.

Myth 5. Poison ivy cannot cause a rash after the leaves fall.

False. The leafless vines can cause a reaction in winter because all parts of the plant, with the possible exception of the pollen, contain uroshiol.

Myth 6. Some individuals are so sensitive, they can get a rash from being near poison ivy even though they don't touch it.

False. Uroshiol is not volatile and only becomes airborne when droplets are suspended on particles of smoke. Burning poison ivy plants can send microscopic droplets of uroshiol into the air.

Uroshiol can be picked up from pets, tools, and clothing. If you used gloves to pull those weeds, were you careful how you removed those gloves? Did you pet Sparky after his romp in the weeds? Did you handle those dirty jeans your husband wore as he mowed the field? Wouldn't it be great if uroshiol were bright, fluorescent orange?

Myth 7. Some individuals are immune to poison ivy.

True, but don't take that too seriously. In a way, most of us are "immune" as youngsters. That means, we can be exposed to the plant without any significant reaction. Those early exposures, however, do make physiological changes to the immune system that are not readily apparent. T-cells, one of several specialized agents designed to fight invading substances, viruses, and bacteria, develop slowly with each exposure. Lots of exposures speed the process as we become "sensitized."

Eventually, they reach a level where they concentrate at the site of contact with uroshiol and cause the red inflammation we blame on poison ivy. Usually, we become sensitized to poison ivy in our teen years and continue to react to it thereafter.

Myth 8. There are no magic cures for poison ivy.

True, unfortunately. The rash usually runs its course in about a week. Think of it as the time for our body to recover from its snit and get back to normal. After all, the uroshiol has probably been washed away long before your body calms down. During this miserable week, various home cures are often used to stop the itching and relieve the soreness. Most families have such remedies handed down through generations. Some of these cures are worse than the initial poisoning and may cause poisoning of their own.

If you can't grin and bear it for a week, ask your doctor's advice before you spend time and money on half-baked cures that could be expensive, ineffective, or even harmful.

Enjoy your yard anyway,
Bill Einsig

Appropriate Standard:
3.7.4C. Describe the nature of technological and scientific knowledge: Distinguish between a scientific fact and a belief (PDE, Science and Technology Standards)