Poison Oak: Identification and Treatment

What's the Difference Between Poison Oak and Poison Ivy?

By Samantha Caveny
June 24, 2019

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

“Leaves of three, let it be!” “Hairy vine, no friend of mine!” Learn how to spot poison oak, tell the difference between poison oak and poison ivy, and treat a poison oak rash. 

What is the Difference Between Poison Oak and Poison Ivy?

Poison oak is a relative of poison ivy. There are many similarities:

  • Both plants contain the same toxic resin, urushiol in all parts of the plant (toxic to humans but harmless to animals). 
  • Both plants have three leaflets, white flowers in spring, and can grow as a vine or a shrub.
  • Leaflets can range in size from the length of your thumb to the length of your hand.
  • Middle leaflet has a notably longer stem than the two side leaflets, though more obvious in poison ivy than poison oak.
  • Depending on the season, leaf color can range from green to orange and even a dark purplish-red.

But they are indeed different plants. In North America, there are two species of poison oak: Atlantic (Eastern) and Pacific (Western). 

Poison ivy (left) vs. poison oak (right)
Poison ivy (left) vs. poison oak (right)

How to Identify Poison Oak

  • 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. 
  • Leaf shape resembles an oak leaf (hence the name, poison oak), but it’s not a member of the oak family.
  • Leaflets are duller green than poison ivy and usually more distinctly lobed or toothed.
  • Leaflets have hairs on both sides, unlike poison ivy.
  • Poison oak tends to grow at elevations between sea level and 5,000 feet.
  • While the fruit of poison ivy is the color of pearls, poison oak fruit (called “drupes”) has a tan color.

At the end of the day, just remember: Leaves of three, let it be. In other words, if you see a plant with clusters of three leaves, don’t touch it!

Left: Poison Oak can be red in the fall, and its berries are tan when mature. Right: Poison Oak leaflets showing coloration.

Poison Oak Symptoms

Symptoms of poison oak include itchy red rashes that can resemble burns, swelling, and even blistering.

Symptoms can take 24-48 hours or even up to a week to show up, particularly if its your first exposure! 

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. Upon contact with your body, urushiol immediately forms a chemical bond to the skin and causes an almost unstoppable allergic reaction. Urushiol will stay on clothes, pets, or other materials for months, and its potency lasts. This means that you could even get poison oak without going anywhere near it. 

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.

Danger: Smoke inhalation from burning poison oak can send you straight to the emergency room. Avoid burning this plant (and poison ivy)!

Poison Oak Treatment

Your best chance at avoiding a reaction is to treat poison oak within 10 minutes of contact.

Urushiol is not water-soluble! Use strong soaps (like dish soap) and wash with cold water to keep the oils from spreading. Cleanse the area of contact within the first ten minutes, then rinse off with cold water. As urushiol can remain active for years, you’ll want to wash any clothes, items, or furniture that may have come into contact with the invisible oily residue.

If you don’t catch the exposure immediately, treat the resulting itchy rash and blisters topically with calamine lotion, baking soda pastes, aloe vera, and a number of commercial products.  If you don’t mind mixing breakfast and skin care, one tried-and-true remedy for itchy skin is oatmeal.  Since poison oak rash is the same as the poison ivy rash, see more remedies on our poison ivy page. If poison oak is extremely serious, speak to your doctor about a prescription.

Of course, the best remedy is always prevention; study our photos so you can recognize poison oak.

Have you ever had a run-in with poison oak? Tell us about it in the comments below!



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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

Don't count on it

My dad was able to pull up poison ivy with bare hands with no reaction... right up until the time he wasn't. Consider yourself lucky you don't react but don't count on it always being the case.