Christine O’Connor

Poison Ivy

Most of us have heard the saying “leaves of three, let it be.” That oversimplification might cause some to dodge strawberry, clover, and many other attractive, innocuous plants.

Toxicodendron radicans, better known as poison ivy, is a widespread noxious plant, notorious for causing allergic skin reactions in the majority of humans that come into contact with this plant.

Poison ivy contains urushiol, an odorless, oily substance emitted by the plant when it is disturbed.  Urushiol is also found in poison sumac and poison oak, as well as a variety of nut trees and others.

Urushiol causes varying degrees of skin irritation, depending on an individual’s sensitivity. Reactions range from mild dermatitis and itching to large patches of painful, blistering skin.  

Poison ivy is not picky as to growing conditions, thriving anywhere from shady woodlands to sunny flower beds. It can resemble a shrub or imitate a tree-like habit, using hairy aerial roots to scale all manner of objects, from trees to power poles, stone fences, and masonry walls.

Many species of birds and mammals consume its high fat berry clusters or “drupes” when it fruits during the growing season and throughout the fall and winter. So, it’s no wonder these plants pop up in unexpected places from seeds that have passed through animals’ digestive tracts.

All parts of the plant contain urushiol, even after the plants have been dead for years, so great care must be exercised to safely dispose of yard waste. Extreme caution is required when burning brush, for errant poison ivy branches or wood with poison ivy vines clinging to it will result in urushiol being carried in the smoke and potentially into lungs of humans. Open burning of poison ivy is so dangerous, it’s against the law to do so in many states.

Domestic pets exposed to poison ivy can harbor urushiol on their coats, so its advisable to bathe pets after romps in the fields and trees.  Launder towels and wash collars,  leashes, and any pet toys that may have gotten urushiol on them. Urushiol can also be transferred to the skin if it’s left on clothing, footwear, gloves, and tools, so it’s important to thoroughly clean them after using. Rubbing alcohol is effective in removing urushiol, so keep a bottle or two handy when enjoying outdoor activities.

Some people have minor reactions to urushiol and will benefit from topical applications of  a variety of over-the-counter remedies; there is also a benefit to calamine lotion, baking soda paste, oatmeal baths, and cool compresses.

People who have a severe reaction to urushiol should seek medical attention. According to the Mayo Clinic, those include folks who have the rash on their face or genitalia, have blisters that show signs of infection by oozing pus, have a fever of over 100 degrees, or have a rash that persists for more than a few weeks.


Knowing what poison ivy looks like and the vast places it could be hiding allows us to give poison ivy a wide berth, avoiding the noxious plant. However, it’s a bit more challenging to stay off the menu of female mosquitoes that need human and animal blood to nourish their eggs’ development.

A significant number of mosquito-borne diseases have shown up in the United States, including encephalitis; yellow and dengue fevers; and West Nile virus, Zika virus, and the lesser known chikungunya virus. Reduce the odds of vulnerability to the bitey female’s needle-like proboscis by using some simple precautions.

Following a number of blood meals, the female mosquito lays her eggs in any amount of stagnant water. It can be a puddle or water in a cup left outdoors. Other typical offenders are buckets, saucers under flowerpots, clogged gutters, tarps, garbage cans, and a host of other places in the average yard.  Water troughs, water buckets, and birdbaths should be emptied and refilled every few days to prevent eggs from developing into “wrigglers,” the larval stage of mosquito metamorphosis.  Otherwise, add a device such as an appropriately rated pump to keep the water moving.

Female mosquitoes are known to be drawn to exhaled carbon dioxide, body heat, movement, and lactic acid exuded by sweat glands, especially during exertion.  Mosquitoes generally prefer moderate temperatures, around 80 degrees Fahrenheit; moderate to high humidity; and after a rain.  They are also a nuisance at dusk, dark, and dawn, but will avoid the hottest time of day when they can easily dehydrate and perish.

The first line of personal defense is to cover up as much as possible in light-colored clothing, for it is believed that the females are attracted to dark colors. And, as mosquitoes are notoriously weak fliers, save some outdoor pastimes for windy days. When sitting outdoors, an oscillating fan may be sufficient to mimic windy conditions and discourage the mosquitoes’ flight.

And, like with poison ivy, shower as soon as possible after exposure and treat any itching that might be present with any number of home or over-the-counter remedies.

Seek medical attention if symptoms persist or worsen.  

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