You’re a landscape maintenance worker who often works in wooded areas or among weeds or tall brush. You generally wear a long-sleeved shirt, long pants, socks, sturdy boots or shoes and gloves, but on this particular day it’s extremely hot, so you wear a short-sleeved shirt to work and leave the gloves in your truck.

A day or two later, an itchy rash breaks out on part of your arm. A similar rash that starts as small, red bumps subsequently appears on your hand. You try to ignore it, but after awhile blisters develop and the rashes begin to ooze.

It’s very likely that you came into contact with a poisonous plant. Exposure to the oil found in plants such as poison ivy, poison oak and poison sumac can not only be annoying, but in some cases, may be much more serious. Exposure to wild parsnip can result in large blisters that leave scars lasting as long as two years.

“Knowing what these plants look like—identification—is key,” says Thao Le, marketing director for Hyland’s, a company that develops and markets homeopathic products, including a product that helps prevent poison ivy, oak and sumac rashes before they start. Prevention, she adds, is also critical. “Most people believe that wearing protective clothing is sufficient, but that is not true. The oils can stay on your tools or clothes. Wearing protective clothing is not enough.”

How do you identify a poisonous plant? Numerous resources are available, including the cooperative extension service in your area, various web sites and your state department of natural resources. One good resource is, a first aid and consumer health information Web site written by physicians. This Web site describes poison ivy, poison oak and poison sumac as follows:

  • Poison ivy—Generally found east of the Rocky Mountains. The plant grows as vines or shrubs, with leaves that have either smooth or notched edges, often clustered in groups of three, but may also be arranged in groups of five or seven.
  • Poison oak—Commonly grows west of the Rockies. Usually grows as a small bush, but sometimes as a climbing vine. The leaves have smooth edges and cluster in groups of three, five or seven.
  • Poison sumac—The leaves are generally oval-shaped and smooth, and have seven to 13 leaves on each stem. Poison sumac is less widespread than poison ivy and poison oak, but it does grow in certain parts of the country, including wet areas of the Southeast and in the Midwest.

The appearance of these plants varies from region to region and with the seasons.

In some parts of the country, including the Midwest and New England, landscape workers may also come into contact with wild parsnip, which is commonly found along roadsides, in poorly maintained prairies or bordering farmed fields. Wild parsnip grows to be 4 to 5 feet tall. When in bloom during the summer months, it has many large flat clusters of yellow flowers on a single, thick stem.

Here is some additional information about poisonous plants:

  • The poisonous substance from poison ivy, poison oak and poison sumac is called urushiol oil. The oil is found in all parts of the plants, including the leaves, roots and stems. You can become exposed to the oil not only through skin contact with the plant, but also by touching clothing, tools, equipment or pets that have been in contact with the oil from one of these plants. Urushiol oil can stay active on surfaces, including dead plants, for several years.
  • It’s important not to burn these plants because you can inhale urushiol oil from the smoke of burning plants and wind up with serious lung irritation.
  • Exposure to the urushiol oil in poison ivy, poison oak or poison sumac causes an itchy rash that usually appears within 24 to 48 hours. In some cases, it may not appear for a few days. The rash generally starts out as small red bumps, and then later develops into blisters. Different areas of the skin may break out at different times.
  • People who are highly sensitive to poisonous plants may have an anaphylactic reaction. Among the symptoms are swelling of the face and throat, difficulty breathing, dizziness or even loss of consciousness. If any of these symptoms are present, seek professional emergency medical assistance immediately. Also, if you know you are highly allergic to these plants, carry an EpiPen (an auto-injector that administers epinephrine).
  • If your skin comes into contact with wild parsnip’s poisonous sap and is then exposed to sunlight, a rash will generally appear one to two days later. Symptoms range from slightly reddened skin to large blisters, which may feel like a mild to severe sunburn. The blisters do not itch, but leave brown scars that last for several months to two years.

Prevention and treatment

Be on the lookout for poisonous plants in your area. Since it might be difficult to completely avoid them when mowing or performing other tasks, take the following steps:

  • Dress appropriately. Wear a long-sleeved shirt, long pants, gloves, sturdy shoes or boots and socks.
  • If you are working in an area with poisonous plants, thoroughly wash any clothing that may have come into contact with them at the end of each day. Be careful not to touch the clothing with your bare hands.
  • Remember that your shoes, tools and equipment can also retain the poisonous urushiol oil for some time. Clean them off with water and rubbing alcohol. Wear gloves, then discard the gloves when you are done.
  • If you are in an area where wild parsnip grows, work in the early evening as much as possible to minimize sunlight and activation of the blistering process should you be exposed to the plant’s sap. See a doctor if a burning sensation develops.
  • Take quick action if you know you have been exposed to a poisonous plant. In the case of poison ivy, poison oak and poison sumac, the first 10 minutes are critical, Le notes. If possible, clean the exposed skin with rubbing alcohol, then wash it with water. Doing this may not stop the outbreak of the rash if more than 10 minutes have gone by, but it can help prevent further spread. Remember not to touch the affected parts of your skin with your bare hands.
  • Promptly seek professional emergency medical help if you have a severe reaction to a poisonous plant.