Poison Oak: Identifying and Treating Poison Oak

Difference Between Poison Oak and Poison Ivy

Samantha Caveny
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Poison oak can be a harmful plant if you touch it, as its urushiol oil will cause a nasty rash.

California State University Channel Islands

Here are ways to identify poison oak as well as some home remedies to treat poison oak rash. 

What is the Difference Between Poison Oak and Poison Ivy?

Poison oak is a counterpart of poison ivy. They contain the same toxic resin, urushiol, and their rash and treatments are the same, but they are indeed two different plants.  

Poison oak is similar to poison ivy in that it can grow as a vine or a shrub. A major reason that poison oak and poison ivy are often confused is that poison ivy and poison oak leaves both have three leaflets. The leaves also vary in color from reddish in the spring, green in the summer, and reddish or yellow in the fall. The leaves have distinguishing characteristics, though. Poison oak leaves are lobed—resembling oak leaves—and have small hairs, while poison ivy leaves are smooth.

While the fruit of poison ivy is the color of pearls, poison oak fruit has a tan color.

Poison Oak Plant Identification: What Does Poison Oak Look Like?

  • Eastern poison oak is a low-growing, upright shrub. It can grow to be about 3 feet tall, sometimes giving it the appearance of a vine. Western poison oak can grow either as a shrub or a vine, causing it to be even more readily confused with poison ivy.
  • The leaves of poison oak stand out because they are lobed, causing them to look like the leaves of oak trees (hence the name, poison oak).
  • The middle leaflet is usually lobed symmetrically, while the other two leaflets are lobed irregularly.
  • Leaflets are usually about 6 inches long, and they have a coating of fine hair.
  • As stated above, poison oak can have a green, red, or yellow color depending on the season.
  • Poison oak flowers are white, and their fruit is tan.

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Poison oak can be red in the fall, and its berries are tan when mature. Photo Credit: A. McTavish, San Francisco State University. 

Poison Oak Rash: Identification and Home Remedies

Poison oak, like poison ivy, contains urushiol. This oily substance is what causes a poison oak rash, and it can be almost impossible to avoid. Urushiol will stay on clothes, pets, or other materials for months, and its potency lasts. This means that you could get poison oak without going anywhere near it. In an attempt to avoid urushiol, it is best to wash clothes and pets when you know they have been in an area that contains poison oak. Use only cold water at first, as it will help to prevent the oil from spreading. After an initial rinse, use a strong soap, such as dish soap, to help break down any remaining oil.

The urushiol resin can cause harsher reactions for those who have been exposed to it before. Sensitivity to urushiol might decrease if you do not come into contact with it until later in life. Only about 15 percent of people are resistant to urushiol, so don’t feel safe around poison oak unless you are absolutely sure you are resistant. You also may become sensitive with repeated exposure, so your resistance might be short-lived.

The poison oak rash is the same as the poison ivy rash, as both are caused by the toxic resin urushiol. You can read about the symptoms and identifying features of an urushiol rash, as well as the home remedies that can ease the pain from a poisonous plant rash, on our poison ivy page. If you need more home remedies to ease the itch or think that poison oak might not be the culprit, try these great tips. If you don’t mind mixing breakfast and skin care, one tried and true remedy for itchy skin is oatmeal!

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Poison Oak and Ivy

I have never been "allergic" to either one. I can pull it up bare handed and not have any effects. Others just have to get fairly close and they are covered with Calamine lotion the next day. When I was in my 20's I would go White Water Canoeing with some buddies. One guy brought his family and we needed a bigger campsite so we went up the hill and found a bigger one. They put their tents on one side and I sat mine on the other side. On the way home they said "Stay away from me. Your tent was in Poison Ivy and oak". I said "Oh My God. Why didn't you tell me"? And they all laughed. The next day at work Frank and Danny were both covered in Calamine Lotion. When they saw I didn't have any on me, they asked "Didn't you get all that poison Ivy on you? Your tent was set up right next to it." I said I know, but I'm not allergic to it and you're both scratching your selves to death". And I laughed because they like to mess with people and think it's funny when something bad happens to someone instead of helping or informing them about something. I said "Jokes On You". I wasn't gonna say that if YOU get withing 20 feet of it (from the way the wind was blowing) that YOU"D GET EAT UP WITH IT. hahaha So they thought they were gonna laugh at me when I got the last laugh and it was the last time they asked me to go canoeing with them. Talk about MAD. I'd ask them if they found any NEW Poison Ivy or Oak patches and they'd turn red and not from the Ivy or oak. haha