New! Sign up for our free email newsletter.
Reference Terms
from Wikipedia, the free encyclopedia

Poison ivy

Poison ivy is a woody vine that is well-known for its ability to produce urushiol, a skin irritant which for most people will cause an agonizing, itching rash. Poison ivy grows vigorously throughout much of North America. It can grow as a shrub up to about 1.2 m (4 ft) tall, as a groundcover 10-25 cm (4-10 in) high, or as a climbing vine on various supports. Older vines on substantial supports send out lateral branches that may at first be mistaken for tree limbs. The reaction caused by poison ivy, urushiol-induced contact dermatitis, is an allergic reaction. For this reason some people do not respond to the "poison" because they simply do not have an allergy to urushiol. However, sensitivity can develop over time. For those who are affected by it, it causes a very irritating rash. If poison ivy is burned and the smoke then inhaled, this rash will appear on the lining of the lungs, causing extreme pain and possibly fatal respiratory difficulty. If poison ivy is eaten, the digestive tract and airways will be affected, in some cases causing death. Urushiol oil can remain viable on dead poison ivy plants and other surfaces for up to 5 years and will cause the same effect.

Related Stories
 


Health & Medicine News

October 6, 2025

A chance encounter with plastic waste on a tropical beach sparked a deep investigation into what those fragments mean for human health. The research reveals that bottled water isn’t as pure as it seems—each sip may contain invisible ...
A University of New Mexico scientist is revealing what might be one of the most overlooked causes of dementia — damage in the brain’s tiny blood vessels. Dr. Elaine Bearer has created a new way to classify these changes, showing that many people ...
Scientists studying tiny roundworms have uncovered how the secrets of a long life can be passed from parents to their offspring — without changing DNA. The discovery shows that when certain cellular structures called lysosomes change in ways that ...
Over 40% of fatal crash victims had THC levels far above legal limits, showing cannabis use before driving remains widespread. The rate didn’t drop after legalization, suggesting policy changes haven’t altered risky habits. Experts warn that the ...
A new study shows glioblastoma isn’t confined to the brain—it erodes the skull and hijacks the immune system within skull marrow. The cancer opens channels that let inflammatory cells enter the brain, fueling its deadly progression. Even drugs ...
Stanford scientists found that aging disrupts the brain’s internal navigation system in mice, mirroring spatial memory decline in humans. Older mice struggled to recall familiar locations, while a few “super-agers” retained youthful brain ...
Researchers from Leeds found that overeating is driven more by what people believe about food than by its actual ingredients or level of processing. Foods perceived as fatty, sweet, or highly processed were more likely to trigger indulgence. ...
Scientists discovered that lifelong social support can slow biological aging. Using DNA-based “epigenetic clocks,” they found that people with richer, more sustained relationships showed younger biological profiles and lower inflammation. The ...
When cancer cells are physically squeezed, they mount an instant, high-energy defense by rushing mitochondria to the cell nucleus, unleashing a surge of ATP that fuels DNA repair and survival. This newly discovered mechanism, visualized in real time ...
Researchers have uncovered how a protein called MRAP2 acts as a key regulator of hunger. It helps move the appetite receptor MC4R to the cell’s surface, allowing it to send stronger “stop eating” signals. The discovery offers new hope for ...
A massive new study combining observational and genetic data overturns the long-held belief that light drinking protects the brain. Researchers found that dementia risk rises in direct proportion to alcohol consumption, with no safe level ...
The STEP UP trials revealed that a 7.2 mg dose of semaglutide led to greater weight loss than the currently approved 2.4 mg dose. Nearly half of participants lost 20% or more of their body weight, ...

Latest Headlines

updated 12:56 pm ET