Skin contact with the oil of a poison sumac plant leads to an itchy, burning, allergic skin reaction. You can’t contract the rash from another person, but the plant’s oil can transfer from your clothing.

Hiking and biking in the parks and woodlands are popular outdoor activities, but some native plants can quickly turn your outing into a miserable experience.

One such plant is poison sumac, a deciduous, woody shrub or small tree. Poison sumac (Toxicodendron vernix) inhabits swamps and other wet areas as well as pinewoods and hardwood forests.

Poison sumac is considered more allergenic than both poison ivy and poison oak. These are other well-known plants that are also in the Toxicodendron genus of the sumac family.

Poison sumac releases an oil known as urushiol when the plant is bruised or damaged. Skin contact with the oil of a poison sumac plant causes an allergic skin reaction known as contact dermatitis. All parts of a poison sumac plant are poisonous and the oils remain active even after the plant dies.

Symptoms of a poison sumac rash appear 8–48 hours after exposure and can last for weeks. Some people are more sensitive to the plants and will have harsher symptoms. The rash itself is not contagious, but the oils can be spread if they remain on the skin, clothing, or shoes.

Symptoms of a poison sumac rash include:

  • itchiness
  • burning sensation on the skin
  • redness
  • swelling
  • watery blisters

Symptoms can interfere with a person’s day-to-day activities depending on where the rash occurs on the body and how much it spreads. People who work outside in the woods or swamp areas are particularly susceptible to poison sumac rash.

Poison sumac is found in swamps, wetlands, pinewoods, and hardwood forests. It can be found along the eastern and southern quadrants of the United States. Poison sumac is particularly abundant along the Mississippi River and swampy areas of the Southeast.

Poison sumac is characterized by:

  • reddish stems
  • leaves that consist of 7–13 leaflets arranged in pairs with a single leaflet at the end
  • elongated leaflets with a smooth, velvety texture, smooth edges, and a V-shaped point
  • bright orange leaves in the early spring that later become dark green and glossy, and then turn red-orange in the fall
  • small, yellow-green flowers in clusters
  • ivory-white to gray fruits that are loosely packed

Similar plants

Poison sumac is more similar to poison ivy and poison oak than it is to other sumacs. Winged sumac (Rhus copallinum) looks similar to poison sumac, but is nonallergenic (doesn’t cause an allergic reaction). Winged sumac can be distinguished from poison sumac by its 9–23 leaflets and red berries. The most widespread sumac — staghorn sumac — is non-poisonous. Staghorn sumac has bright orange or red berries growing at the edge of its stems. Its leaves also have saw-toothed edges, unlike poison sumac. While poison sumac likes to grow in wetlands, most other sumacs prefer drier areas with well-drained soils.

Poison ivy and poison oak are two other commonly known poisonous plants that can cause a rash, but they look different from poison sumac. Poison ivy typically has three shiny green leaves (or red in the fall) budding from one small stem. Poison oak also typically comes in leaves of three.

If you’re exposed to poison sumac, the first step is to remove the oil from your skin. Don’t wait until a reaction appears on your skin to take action; a rash could take hours to develop.

Wash any exposed parts thoroughly with soap and cool water. Don’t use warm water, as this could cause the oils to spread. The Centers for Disease Control and Prevention recommends rinsing with rubbing alcohol, specialized poison plant washes, degreasing soap (such as dishwashing soap), or detergent, along with lots of water. Take special care to clean under the fingernails to avoid spreading the oil to the eyes and other parts of the body. Clean all contaminated clothing, shoes, and gear with detergent several times.

There is no cure for the rash. You’ll have to wait for the symptoms to pass. There are many over-the-counter remedies to help with your symptoms in the meantime, including:

  • calamine lotion
  • hydrocortisone creams
  • topical anesthetics, such as menthol or benzocaine
  • oral antihistamines, such as diphenhydramine (Benadryl)

You can also take an oatmeal bath to help relieve the itching.

If the rash is on the face or genitals, spreads over a large part (30–50 percent) of the body, or you have a high fever (over 101°F), see your doctor. A doctor may prescribe oral or strong topical steroids to help reduce inflammation. You should also make a visit to your doctor if you think your rash has become infected due to scratching. Treatment will usually involve antibiotics.

Call 911 or go to a hospital emergency room immediately if your eyes swell shut or you have difficulty breathing.

Scratching the skin can lead to an infection. Symptoms of an infection include redness, pain, pus, and oozing from the blisters.

If the oil is inhaled, which may occur if the plant is burned, it can lead to a dangerous lung irritation. This can be fatal. Symptoms of lung irritation include coughing, difficulty breathing, and wheezing.

Poison sumac is one of the most toxic plants in the United States, causing a horrible skin reaction that can persist for weeks. Thankfully, poison sumac is much less common than poison oak and poison ivy.

If you work or spend a lot of time in wetlands, swamps, or shady hardwood forests, being able to identify local types of poison sumac throughout the seasons is key to avoiding exposure. If you do come in contact with poison sumac, clean the area immediately with cool, soapy water and avoid scratching. as this could lead to an infection.