Poison Ivy treatment and health risks (Toxicodendron radicans)
November 20 2016

More than 80 percent of the world's population will develop an itchy skin rash if exposed to poison ivy. Poison ivy rash is the most common allergic reaction in the USA.

Allergic contact dermatitis caused by the Toxicodendron (formerly Rhus) species-poison ivy, poison oak, and poison sumac-affects millions of North Americans every year. In certain outdoor occupations, for example, agriculture and forestry, as well as among many outdoor enthusiasts, Toxicodendron dermatitis presents a significant hazard.

Treatment
Take an oatmeal bath in a solution bought at the drug store.
Take a bath and add 1 cup of baking soda to the bath water.
Take a cool shower.
Apply calamine lotion to the rash.
Apply a cool compress (wash cloth dampened with cold water) to the itchy skin.
Don't use a topical antihistamine, which could worsen the rash. But an oral antihistamine if fine.

Cause
The itch of poison ivy is caused by an oily sap called urushiol, which is also found in poison sumac and poison oak.

Carbon dioxide levels rising causing more problems
Studies have shown that higher levels of carbon dioxide in the atmosphere are creating a proliferation of poison ivy throughout the U.S. -- even in places where it wasn't growing before.

When scientists increased carbon dioxide to the levels expected to be seen at the middle of this century due to emissions from burning of fossil fuels and other pollutants, poison ivy grew more than twice as fast. The plants also produced more of a type of urushiol, the substance that causes an allergic reaction. Dr. Jacqueline E. Mohan of The Ecosystems Center at the Marine Biological Laboratory in Woods Hole, Massachusetts and her colleagues studied plots of a forested area surrounded by PVC pipes that pumped out carbon dioxide, allowing them evaluate the effects of greenhouse gas in a real-life forest environment. They compared poison ivy growth over a six-year period in three carbon dioxide-enriched areas and three areas with normal air. The average carbon dioxide levels are now about 370 micrograms per liter. Carbon dioxide levels were increased to 570 micrograms per liter, the level that will be reached by mid-21st century if global warming is not reduced. Under the high carbon dioxide conditions, the poison ivy plants grew 150 percent faster every year than the control plants. In addition, the plants contained 153 percent more of the urushiol compound that causes an allergic reaction. Scientists have observed increased worldwide growth in vines, which is in some cases choking out the regrowth of trees. Vines benefit from extra carbon dioxide because the gas fuels photosynthesis. Unlike trees, vines have to devote relatively little energy to growing wood, and can instead pump the extra photosynthesis energy into leaf production. Proceedings of the National Academy of Sciences, Early Edition, May 30, 2006.

Wilderness Environ Med. 2006. Toxicodendron dermatitis: poison ivy, oak, and sumac. Allergic contact dermatitis caused by the Toxicodendron (formerly Rhus) species-poison ivy, poison oak, and poison sumac-affects millions of North Americans every year. In certain outdoor occupations, for example, agriculture and forestry, as well as among many outdoor enthusiasts, Toxicodendron dermatitis presents a significant hazard. This review considers the epidemiology, identification, immunochemistry, pathophysiology, clinical features, treatment, and prevention of this common dermatologic problem.