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Poison ivy

life science Maturity 5-7 Next article →

Poison ivy is a plant that many people know well. It is part of a group called Toxicodendron. This group includes three different species. One is T. orientale, found in East Asia. Another is T. rydbergii, found in much of the United States. The third is T. radicans, which grows in North America and Central America.

Urushiol induced contact dermatitis
Urushiol induced contact dermatitis

Even though it has "ivy" in its name, it is not a true ivy. It is actually in the cashew and pistachio family. This plant can grow as a small shrub or a climbing vine. Many animals eat the plant, and birds eat the seeds. However, most people think of it as an unwelcome weed.

Most people get a skin rash if they touch this plant. This happens because of a clear liquid called urushiol. Urushiol is found in the plant sap. It is not a true poison, but it is an allergen. An allergen is something that makes the body react. When urushiol touches your skin, it causes itching and red bumps. Sometimes, it can even cause blisters.

Urushiol induced contact dermatitis
Urushiol induced contact dermatitis

The blisters happen because small gaps form in blood vessels. This causes fluid to leak through the skin. If you scratch the blisters, the fluid inside does not spread the rash. That fluid is made by your own body, not by the plant.

Learning how the plant looks can help you stay safe. You can look for clusters of leaves. Each cluster usually has three leaflets. People often say, "leaves of three, let it be." The leaf shapes can be egg-shaped or long. The edges of the leaves might be smooth or have small teeth.

Urushiol induced contact dermatitis
Urushiol induced contact dermatitis

In the spring, small greenish flowers bloom from May to July. In the fall, the plant grows small white berries. These berries are only a few millimeters wide. It is important to remember that the oil can stay active for several years. You can still get a rash from dead leaves or old vines.

In the United States, over 350,000 people are affected by urushiol every year. About 15 to 25 percent of people are resistant to it. This means they do not get a reaction at all. For others, the rash usually lasts between five and twelve days. Sometimes, a bad reaction can last for a month or more.

If the plant material is burned, the smoke can be very dangerous. Breathing the smoke can cause pain in the lungs. If someone eats the plant, it can damage the inside of the mouth. In very rare cases, a person might even need to go to the hospital.

You can take steps to prevent a bad reaction. If you touch the plant, wash with soap and cold water right away. You can also use rubbing alcohol. If you already have a rash, calamine lotion might help. Some people use oatmeal baths or baking soda to feel better.

Urushiol induced contact dermatitis
Urushiol induced contact dermatitis

Be careful not to spread the oil to your things. The oil can stay on phones, tools, or even pet fur. If you get oil on a surface, wipe it with bleach. This helps stop the oil from causing more rashes. Staying careful helps you enjoy the outdoors safely.

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