The return of warmer weather means returning to many fun outdoor recreational activities such as hiking, biking, boating, and fishing in parks and woodland areas. But spending time in nature can occasionally mean exposure to the state’s native poisonous plants. Found in many natural areas, these plants can quickly ruin a fun outing if people come into contact with them. In Michigan, the most common poisonous plants encountered outdoors are poison ivy and poison sumac, and these plants are the most common cause of allergic skin reactions. Fortunately, doctors at a dermatology practice in Grosse Pointe can help identify rashes caused by poisonous plants and recommend treatment. Identification of poison ivy and poison sumac, the allergic reactions they cause, and treatment options available are detailed below.


Identification of Poisonous Plants


Poison ivy is the common name for Toxicodendron radicans, a plant that typically has three green leaves budding from one stem. This three-leaf pattern gave rise to the famous warning, “Leaves of three, let them be.” Poison ivy is a flowering plant in spring, and its leaves turn red in autumn. It is generally found in eastern North America and Asia. Despite its name, it is not an ivy but rather belongs to the cashew and pistachio family.


Poison sumac is generally found in hardwood and pinewood forests, wetlands, and swamps in the eastern and southern parts of the United States. Poison sumac has leaves that consist of 7 to 13 leaflets arranged in pairs with a single leaflet at the end of a reddish stem. Leaflets are elongated, have smooth edges, and taper to a v-shaped point. Leaves are bright orange in early spring, turning to dark green and glossy in summer, then red-orange in autumn. Poison sumac features small, yellow-green clusters of flowers in spring and ivory or gray fruits in summer.


Causes of Allergic Reactions


Poison ivy and poison sumac are both well-known for causing contact dermatitis in most people who come into contact with them. Contact dermatitis manifests as an itchy, irritating, and occasionally painful rash and is caused by urushiol, a clear liquid found in the plants’ sap. The plants release urushiol when they’re damaged or bruised, so direct contact with any part of the plant—roots, stems, or leaves—causes a rash. If a person has urushiol oil on their fingers, they can easily spread the rash to other parts of the body. People do not usually spread the rash by touching another person who has touched a poison ivy or poison sumac plant because urushiol oil is absorbed by the body very quickly.


Even though urushiol oil doesn’t stay on the skin for long, it can stay on objects for years—so people can easily develop a contact dermatitis rash after touching anything that has urushiol oil on it, such as clothing, shoes, a gardening tool, or a pet’s fur. Urushiol oil is active even after the poisonous plant dies, so handling dead plant matter may also lead to a rash.


If smoke from burning poison ivy or poison sumac is inhaled, lungs and respiratory passages may also experience a severe allergic reaction.


A small percentage of people are immune to urushiol oil; approximately 15% of people will not get a rash if they come into contact with either poison ivy or poison sumac. But 85% of people will develop a rash when they come into contact with these plants, although probably not right away. A contact dermatitis rash can take hours or days to appear, depending on a person’s sensitivity to urushiol oil and how much exposure he or she had. A dermatology professional in Sterling Heights can evaluate the rash and diagnose poisonous plant contact dermatitis.




Signs and symptoms of both poison oak and poison sumac contact dermatitis are similar. Symptoms of milder cases include:


  • Raised red rash
  • Hives
  • Swelling
  • Itchiness
  • Bumps or blisters


Poison sumac may also feature a burning sensation on the skin.


A contact dermatitis rash may show up in streaks, lines, or patches, depending on where and how the poison ivy or sumac came into contact with the skin. The rash may show up in different areas of the body progressively, depending on how much urushiol oil came in contact with a particular area. A few days after blisters in the rash first appear, the blisters may crust and burst, emitting a clear liquid.


Symptoms of more severe cases include:


  • Difficulty breathing
  • Eyes that are swollen shut
  • Fever


Even in a case that starts mildly, scratching the rash area can lead to an infection. Symptoms of an infection include pain, redness, and pus oozing from blisters.



If poison ivy or poison sumac plants are burned, it’s possible to inhale urushiol oil, which can lead to severe lung irritation. Symptoms of severe lung irritation are coughing, wheezing, and difficulty breathing. These symptoms should be treated right away at an emergency medical facility.




Mild poison ivy symptoms should resolve within a few weeks. Poison sumac is considered more allergenic than poison ivy. Symptoms of poison sumac can appear between 8 and 48 hours after contact with the plant and can persist for many weeks.


Many milder cases of poisonous plant contact dermatitis can be treated with over-the-counter remedies to help ease the itch, such as calamine lotion or hydrocortisone cream. Oral antihistamine pills can reduce itching and may also aid sleep.


If a mild contact dermatitis rash doesn’t show signs of healing after 7 to 10 days, it should be evaluated by a dermatology professional in Grosse Pointe for a more definitive diagnosis. Having a doctor evaluate the rash can also help rule out other causes.


In some cases, poison ivy and poison sumac can cause more serious complications that may require medical treatment. In severe cases, the rash can spread to the eyes, mouth, or genitals. If this happens, contact a dermatology practice in Sterling Heights to schedule an appointment with a physician. A dermatologist may prescribe a steroid ointment and possibly an antibiotic if signs of infection are present, such as swelling, pus around the rash, or a rash that is warm to the touch.


In very rare but severe cases, symptoms may require immediate attention. If the rash covers more than a quarter of the body or if symptoms include a fever of over 101 degrees, trouble breathing, or swelling of the tongue or throat, call 911 or go to a hospital emergency room.


Participating in outdoor activities during warmer months is a lot of fun. Being able to identify and avoid poison ivy and poison sumac ensures that the only lasting impact of time spent outdoors is a delightful memory and not a lingering dermatological issue.