Poison oak can be a harmful plant if you touch it, as its urushiol oil will cause a nasty rash.
What's the Difference Between Poison Oak and Poison Ivy?
“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).
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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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When I was a youngster, I use to get poison ivy and oak every yr. Very miserable stuff. One year though I remember specifically, because I had got in poison oak and my left arm was so swollen and blistered up, the Dr.s thought they might have to ampitate it, if it didn't start getting better. I have always had to go get shots after getting poison ivy and oak, but that year didn't seem like shots were helping. When I got a little older, around 18, I used to work out of town for a hazardous material clean up crew. I ended up getting poison ivy on the job, out of state. My bosses brother took me to the hospital for a shot, the Dr. said he would fix me up. That was 30 years ago and I haven't had it since, until two days ago. Not sure what he gave me back then but it sure was worth the jab.
Good article thanks. But... You state poison oak growing to a height of only a few feet. Sorry to disappoint but i can show you poison oak vines 3”-4” in diameter at their base and growing to heights of 25’+ in amongst oak forests. If you go to Montaña de Oro State park on the Central Coast of California (near Los Osos and Morro Bay) and hike the Oats Peak trail or Manzanita trail or numerous others. Both the abundance, size and height of the poison oak will blow your mind. Also, hands down, the very best soap to use is is good old Pyrex Fels Naptha laundry soap bar. It’s pretty much straight Lye soap. Be sure to WASH TWICE in COLD WATER with plenty of Fels, rinse well both times with cold water. I’ve been climbing, hiking and mt. biking on the Central Coast for decades. I’ve spent weeks doing poison oak removal on a coastal ranch. Dug ditches through it installing plumbing systems. Clawed my way through it searching for new and old climbing routes. Been thrown ass over tea kettle off my mt. bike into thick growths of the stuff. I’ve been knowingly covered in poison oak more times than I can count. I’ve had it and it’s a painful experience I don’t ever want again. Fels Naptha works every time, even after hours of exposure. I take this subject seriously because I have a dear friend who back in the early 1990’s unknowingly made dream catchers along with her mom and sister, out of dormant/barren poison oak stalks. All three broke out bad within 24 hrs and were hospitalized and treated with cortisone injections. Her and her sister suffered hard in hospital for over four days and at home after for another week. But their mom got worse after day three, high fever to coma to death in five days from cerebral meningitis due to the urushiol poisoning. I have numerous other stories of run-ins with poison oak but that’s the worst of them.
I have lived in Santa Cruz, California for 35 years and can attest that indeed poison oak grows in huge shrubbery clumps/stands up to 12 feet high and unlimited widths as a stand from the coasts all the way up to the mountains. I regularly see vines up to 3"-4" circumference completely covering multiple trees in mixed forests. In fact, trees can look like poison oak trees once the vines get hold and take over. Even in the winter it can zap you as naked stems or vines. I carry a huge bottle of Tecnu in my car and always take it with me camping. Btw - your pet can be an endless source of exposure if they get the oil on their coat. I'm excited to hear about the Fels Naptha soap, but I hope I don't have to try it!!!! As a Wilderness Guide i'm always looking for the best interventions and treatments in the field, thanks.
Thanks for the wash-up tips.
I live on the central coast of California too, in the canyons east of Pismo Beach. There is a lot of 5+ foot high poison oak shrubbery here, however, behind the house there is a GIANT poison oak vine/tree a few inches in diameter and at least 60 feet tall growing up a tree!
So sorry to hear of your friends' accidental poisoning. Stay safe.
I wouldn't wish oak poisoning on my worst enemy. My rash turned into something that looked like a chemical burn. I'm getting treatment from my family doctor after not getting any relief from over the counter or home remedies.
I would like to know if you can burn the poison oak or ivy after its been cut down and has died, if not how do you get rid of it? Now I have never been allergic to the stuff, and I am on up in years, but I was cutting and cleaning out some poison oak/ivy about 2 weeks ago, and I don't know if maybe in my older years I may have gotten may not as resistible to it as I have always been. I have a very small place on my arm that itches like crazy and it just turns red. I put alcohol, etc on it but it stops but comes back itching. I forgot about trying the calamine lotion. I have always cut down the poison oak and just pulled out the vines and threw them away and most likely burned them, I have a lot of the dead vines to dispose of is why I ask if its safe to burn after it dies? I sure hope I haven't become allergic to it, I am the only one in the family that can remove it with out breaking out and been so thankful that I am not allergic to it. Have a great day.
Never ever burn poison oak or poison ivy, the oils travel in the smoke and can kill you! Lungs swell up and can’t take in oxygen. God bless your home and family
Pat, regarding the spot on your arm. I discovered an effective remedy for poison weed itching 18 years ago. Turn on a hair dryer on High, and train the air on the affected spot, between 6 and 12 inches away, depending on how it feels. The idea is to heat your skin only a few seconds until you feel a definite stinging from the heat. That's it; you should notice welcome relief for a few hours. Good luck.
Hi Obed,
Thank you for sharing your experience. I had had a huge problem twice for a summer last year. I found your idea is a true brilliant. Lana.
I'm 59. I still remember being an early teen and waking up looking like Frankenstein. I had red irritation from my ears running down my neck. I hadn't been in the woods or near any ivy, and knew I was allergic to them (I'm not hyper sensitive but I'm pretty bad. I used to tease I could catch it from looking at a picture).
Not sure what it was, my mother took me to a doctor.
Seems the neighbor had been burning weeds, and I caught the oils falling from the smoke... Internally.
Later on life, while on the military, I woke up one December day to find my face to be the color of my camouflaged uniform. Never seen anything like it. I was black, blue, and I recall green. I worked in the base hospital and called the ER, and they said come IN.
When they saw me and realized I wasn't kidding they took me right to isolation. A doc checked me out, scratched his head, and out me on quarters (instead of being admitted for sent home for rest for 24 hours).
Each day I had to go back in to get out on quarters, seeing a different doc. Come the 5th day, the doc said "if I didn't know better if swear got had poison x internally, but it's December, and they're dormant"
I looked at him and he could tell by my expression something clicked....
The wife and neighbor had made wreaths out of vines and she hung two in our mobile home, heated by forced air, circulating and exposing me... To the now not dormant....
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