Poison Ivy Could Be Getting Itchier

Few things can dampen a day outdoors faster than poison ivy, a.k.a. Toxicodendron radicans. The plant, which often appears as a three-leafed shrub or vine, can prompt a rash thanks to urushiol, an irritating oil in its leaves. Shower within a half-hour of contact and you’ll be generally OK. But thanks to climate change, poison ivy may soon be getting more potent.

Researchers have been keeping an eye on how poison ivy is reacting to a shifting environment. In 2006, Duke and Harvard University scientists published a study in the Proceedings of the National Academy of Sciences demonstrating that poison ivy could double its usual size when there were increased amounts of carbon dioxide in the atmosphere. More CO2 helped the plant with photosynthesis and water usage; CO2 also prompted it to produce more urushiol, meaning it could prove substantially more irritating to human skin.

Increased carbon dioxide in the atmosphere is also what’s bringing on climate change, and this pumped-up version of poison ivy is one result. As carbon dioxide levels continue to increase, so could more irritating and pervasive poison ivy.

The plant is also benefiting from warmer soils. In one experiment conducted at Harvard, an increase of 9°F in soil temperature resulted in poison ivy growing 149 percent faster, far exceeding the 10 percent to 20 percent seen in other plants under the same conditions.

Coupled with the fact poison ivy likes to grow in human-cleared areas like camp sites, it’s likely the plant will become more of a concern in the years to come.

If you’re communing with nature, try to wear pants and long sleeves rather than shorts and t-shirts, and learn to identify possible poison ivy. In addition to having three leaves, it can also appear as a scruffy vine on trees. If a plant you think might be poison ivy has thorns, it’s probably something else.

If you develop a rash after brushing against poison ivy, cortisone cream or calamine lotion should reduce itching until the rash eases in two to three weeks. Any blistering or other signs of infection should be evaluated by a doctor.