Poison ivy, poison oak, and poison sumac are plants that commonly cause a skin rash frequently seen in the summer months.

The rash that develops after exposure to these plants is caused by urushiol, the oil that is found on them. After contact with this oil an itchy, blistering rash commonly occurs.

Poison ivy typically grows in the form of a vine and can be seen throughout the United States. The plant has three shiny green leaves that grow on a red stem.

Poison oak characteristically grows in the form of a shrub and has three leaves similar to that of poison ivy. Poison oak is most frequently found on the West coast.

Poison sumac grows in the form of a woody shrub, and each stem contains seven to thirteen leaves that grow in pairs. This plant can be found abundant along the Mississippi River.

Some people do not develop a rash after initial contact with the oil on the plants. However, subsequent exposure can cause sensitization with rash development. In rare instances, some people never become sensitized to the oil and therefore never develop the rash.

The three most common ways to develop the distinct rash are by direct contact, indirect contact and airborne contact. Direct contact occurs by touching the plants. Urushiol is present on every aspect of the plant – leaves, stems, roots and flowers. Since the oil can adhere to most objects, indirect contact occurs by touching these affected objects (i.e., pet’s fur or gardening tools).

Airborne contact occurs when these plants are burned and particles of the oil are released into the air and can land on the skin.

The rash from contact with these plants often does not develop until 12 to 72 hours after contact with the oil. It is important to note that this rash is not contagious.

The most common signs of the rash are itchy skin, redness, swelling, blisters that appear in streaks or lines, and crusting that develops after blisters burst. The characteristic rash is very itchy and can appear anywhere on the body.

The rash can also continue to appear in other areas when other parts of the body touch the oil or the oil is spread on the skin by touching other areas of the body.

Treatment of the rash is generally aimed at controlling the inflammation, which can be managed by topical steroids. More severe cases may need systemic steroids.

Other treatment recommendations include immediately rinsing the skin with mild, soapy water, washing clothing, washing objects that may have oil on the surface, avoiding scratching, and leaving blisters alone.

The rash typically goes away in approximately one to three weeks.

Mandy Medlin, MSPAS, PA-C sees patients at the Bluffton office of May River Dermatology.