You've probably been warned about poison ivy, as well as similar plants like poison oak and poison sumac, if you've ever been camping or hiking. The "poison" in these names is a bit misleading, as they don't poison, but cause a form of allergic contact dermatitis. This results in the itchy, painful rashes we associate with these plants.
The Facts About "Poison" Plants
The substance that causes a reaction from exposure to all three of these plants is a toxic oil called urushiol, found in their sap. Around 85 percent of people develop a rash after coming into contact with urishiol. Contrary to belief, the rash it causes can't be spread person-to-person, but you can get it from the oil if it's stuck to clothes, pets, gardening tools, or anything else that's come into contact with these plants.
Many people don't get a rash the first time they come into contact with urishiol, as sensitization occurs. The severity of the rash depends on person and can change over time. Symptoms may include:
- Red, itchy skin: usually as an early sign.
- Red rash: can be bumpy, can develop in streaks or patches where skin has come into contact with the oil.
- Blisters: wet, can be small to large.
These symptoms typically last 1 to 3 weeks, and don't spread unless the urishiol comes into contact with other parts of your body. The rashes don't usually develop until 12 to 72 hours after contact, and can develop at different rates. Touching these rashes or their drainage won't cause them to spread.
Identifying "Poison" Plants
You may have heard the old phrase "leaves of three, let it be," which often accurately describes poison ivy's clusters of three leaves. But the three major poison plants are not all the same:
- Found: Throughout most of the U.S.
- Growth: Vine or shrub.
- Leaves Per Stem: Usually three.
- Leaf Color: Intense green in summer; red in spring; yellow or orange in fall. Often shiny with oil.
- Leaf Shape: Spoon-shaped but pointed. Can have smooth or toothed edges.
- Found: More common in Western U.S., sometimes in Eastern U.S.
- Growth: Shrub in Eastern and Southern states, vine or tall grass clump in Western states.
- Leaves Per Stem: Often three, can be up to seven.
- Leaf Color: Intense green in summer; differing amounts of red during rest of year. Textured, hair-like surface.
- Leaf Shape: Rounder and less pointed than poison ivy.
- Found: Wooded, swampy areas in Northern or Southeastern U.S.
- Growth: Tall shrub or small tree.
- Leaves Per Stem: Seven to thirteen.
- Leaf Color: Reddish-green, with small hanging berries that are usually whitish-green.
- Leaf Shape: Pointed with smooth edges.
Avoiding the "Poison" Plants
The best way to prevent rashes from these "poison" plants is to avoid them altogether! How can you do that? Here are some tips:
- Learn what they look like! Many plants look similar, but knowing how to spot these three is invaluable.
- Wash gardening equipment and clothing as well as outdoor sports equipment and clothing regularly.
- Wash outdoor pets regularly, using a pet shampoo and rubber gloves.
- Wear long sleeves and pants outdoors whenever possible, especially when working outdoors. Tuck pants into boots, and wear gloves when necessary.
Treating Urushiol Rashes
The first step to alleviating the effect of urushiol rashes is to act quickly. If you think you've come into contact with one of these plants, you should immediately:
Remove clothes and wash them.
Wash all exposed areas on your skin with cool water and soap.
Rinse away any urushiol on your skin with running water.
You may get a rash despite your best efforts! Treatment options are largely about reducing the effects of the rashes and alleviating pain and itchiness. Here are some treatment options:
- Calamine lotion: anti-itch medication that soothes discomfort.
- Hydrocortisone topical cream: soothes discomfort and itching.
- Antihistamines: can reduce itchiness.
- Topical pain relievers.
- Substances to dry out blisters: zinc oxide, zinc acetate, aluminum hydroxide gel.
- Prescription corticosteroid: prescribed to reduce the severity of more intense reactions, especially those on a sensitive area of the body.
- Antibiotic ointment or oral antibiotics: skin inflammation can lead to infection, which can cause further, dangerous problems.
Don't neglect calling a doctor if the rashes become too uncomfortable. These may be signs of infection, and will require antibiotics. Watch for these signs:
- Swelling or warmth around the rash.
- Pus around the rash.