Complete Guide to Poison Ivy

Poison ivy rash, also known as allergic dermatitis, is an itchy, red rash that is caused by exposure to urushiol, an oil resin contained in the roots, stems and leaves of poison ivy, poison oak, and poison sumac. 

Because urushiol is extremely sticky, it can attach to a person's skin, clothes, and personal items like camping gear and tools. 

People who are allergic to urushiol can experience severe symptoms when their skin is exposed. 

How to Spot Poison Ivy, Oak and Sumac

Many people don't know what these plants look like, so it's difficult to avoid them when out in nature. 

Here's how to spot poison ivy:

• Poison ivy grows in leaves of three
• In the spring, leaves may be reddish and then turn white 
• In the summer, leaves are green
• In the fall, leaves may look orange or burnt red
• In the winter, leaves turn deep read and may be shriveled
• Look for a stem with a taller leaf at the top and two smaller leaves at the sides
• Leaf size can vary from small to large
• May have small berries
• Leaves are smooth with notched edges
• Can grow in large vines or as a ground cover in the eastern United States
• Can grow as a shrub in the northern United States and Canada
• Can grow in both moist areas, like lake fronts, and dry areas, like shady forests

Here's how to spot poison oak:

• Poison oak usually grows in leaves of three, but some may have several clusters with more than three leaves
• Leaves are typically more rounded at the edges than poison ivy
• Leaves are more deeply ridged than poison ivy and may have a hairy texture
• Leaves can be green, red or a combination of colors
• Typically grows as a small, erect shrub
• Can have greenish white berries during summer
• Grows west of the Rocky Mountains (Pacific poison oak)
• Grows in Texas, Oklahoma, Kansas and the Southeastern United States

Here's how to spot poison sumac:

• Unlike poison ivy and oak, poison sumac is a shrub or small tree
• Typically grows in swampy areas
• Leaves grow in large clusters of around 7-13 leaves per cluster
• Leaves have have smooth edges and an oval shape
• Leaves are glossy and green in summer
• Leaves turn reddish or orange in autumn

No person is completely immune to urushiol, but some people may be more sensitive to its effects than others. 

Humans are not born with a sensitivity to urushiol oil, but we develop it over time. The first time we come in contact with the oil, our immune systems begin to formulate a reaction to it. This reaction doesn't alway manifest on the skin during first contact. A rash may not occur until the next time you come in contact with the oil. This is why many people don't develop a rash the first time they touch poison ivy, oak or sumac. 

Other people may develop a rash in 2-3 weeks after the first time they come in contact with urushiol. 

The second time you come in contact with urushiol, you may develop a rash within 72 hours. 

The best way to avoid an urushiol-related rash caused by poison ivy, oak or sumac is to avoid contact with these plants.

To avoid plants that contrain urushiol, it's important to know what the leaves look like, how they grow, and where they grow. 

Check out our graphic on how to spot these leaves, or read about what each plant looks like in our How It Works section on this page. 

You should also take important protective measures every time you're outside:

• Wear protective clothing when you're outside (long sleeves, long pants, socks and boots)
• Use an urushiol blocker when you're in areas that may house poison ivy, poison oak or poison sumac
• Machine wash any clothes or linens you wore or used while outside
• Wipe down all tools and equipment with rubbing alcohol after being outside
• Shower in warm water soon after being outside, making sure to carefully clean your hands and beneath your fingernails using soap

If you develop a mild rash after coming in contact with poison ivy, oak or sumac, there are some things you can do to decrease the severity of the rash. 

Easy treatments you can do at home:

• Don't scratch the rash
• Don't pop or irritate any blisters that appear
• Use an oatmeal bath to relieve itchiness and soothe the irritated skin
• Apply calamine lotion to affected areas
• Over-the-counter creams like aluminum acetate, calcium acetate and aluminum sulfate can help control oozing

It is vital that you visit a healthcare professional if your rash causes any of the following symptoms:

• Temperature over 100 degrees Fahrenheit
• The rash spreads to your eyes, lips or genitals
• The rash covers more than 25% of your skin's surface
• Have severe blistering that is itchy and swollen
• A rash that last longer than 10 days