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How to Identify Poison Oak and Treat the Rash

I live in Indiana, and I've run into poison oak many times. This is what I've learned about the plant itself and how to treat the rash.

The poison oak plant that causes this horrific rash.

The poison oak plant that causes this horrific rash.

What Is Poison Oak?

Poison oak is a plant that can cause a horrible rash and blisters when we come in contact with it. It is a relative of the cashew plant, and some say that it grows mainly along the southeastern coast of the United States. In my experience, however, that geographical information isn't true—because here in Indiana, where I've lived my entire life, I've run into this plant many times, in locations all over the state.

Poison oak can grow as a vine or into a bush. The plant is commonly seen climbing trees, fences, and other types of walls, including buildings. It receives the name from the fact that the leaves are generally shaped similar to the leaves of an oak tree, even though there is no relation between the tree and the plant.

Generally, the leaves will be in clumps of three. This consistent trait led to the old saying, "leaves of three, let it be," which helps so many people steer clear of poison oak and poison ivy. The edges of the leaves have curves in them that form the shape.

The vine portion of the plant is woody, and there can be little protrusions coming out that can give the vine a hairy appearance. The older leaves on the plant will also have this hairy look to them, along with the so-called fruit that the vine produces.

The poison oak rash on my left foot.

The poison oak rash on my left foot.

What Causes the Poison Oak Rash and What You Need to Know About It

If you are unlucky enough to come across this plant and are one of the estimated 80% of the population that will have a reaction to it, you have fallen victim to the plant's defensive oil called urushiol. Urushiol is what causes the ugly rash and blisters that develop when you have been exposed to the plant.

Urushiol is an oil that is contained in every portion of the poison oak plant. It is in the leaves, the vine, the fruit, and the roots. The amount of urushiol varies in the plant depending on what time of year it is, but it is always there. Complaints of poison oak rashes are more common in the spring and summer months, so the general consensus is that the urushiol concentration is higher in the plant during those times.

Exposure can happen by simply brushing up against the plant. Anything that disturbs the plant or bruises it will receive a transfer of urushiol. This includes any tools, clothing or parts of the skin that are exposed.

The urushiol oil can remain on an item for an extended period of time. Using a rake or other hand tool can cause a reaction at a later date if that tool had come into contact with a poison oak plant and wasn't cleaned afterward. Likewise, clothing like shoes and gloves can also hold urushiol and cause the rash at a later date.

Contrary to popular belief, our mothers and grandmothers were wrong on a few things when it comes to poison ivy and poison oak rashes, even though their hearts were always in the right place. Here are a few things that just aren't true:

  1. Poison oak is not contagious. You will never catch this rash from another person.
  2. Scratching the rash does not cause it to spread on your body. The only places that develop the rash are the places that have come into contact with the urushiol from the plant. Different places on the body take longer for the rash to appear, and that's why it appears that it is spreading when in fact, it doesn't.
  3. Depending on how long ago it was when you were exposed, washing with straight water can spread the urushiol on your body if it is still on the skin. The old prevention of taking a shower after you know you have been exposed to "wash off" the oil can make it worse. Oil and water do not mix! The best thing to use for this "shower" is rubbing alcohol. It will grab the oil and be able to remove it from the skin, if the plant oil has not soaked in yet.

Timeline for Most Poison Oak Rashes and What You Can Expect

TimelinePoison Oak Rash Appearance

Moment of Contact


8-24 Hours

Itching starts, may start to see small red bumps.

1 day to 7 days

Itching increases, blisters may form, rash becomes worse

7 days to 14 days

Process starts to reverse (thank goodness!)

Home Remedies to Help Relieve the Rash

There is no cure for a poison oak rash. I hate to say it, but you have to ride it out. There are a few things that you can do to treat the symptoms and keep the rash from driving you absolutely crazy for the approximate two weeks that you will have to deal with it.

  1. Use rubbing alcohol on the rash a couple of times a day. This actually does help take some of the itch out and will help with fighting any infection that might try to creep in while the skin is broken from the rash.
  2. Hot water, as hot as you can stand it, ran over the rash can help relieve the itching for some people. It will itch like the dickens for a few seconds but this method can be done as many times as you need it each day.
  3. You can also try a hydrocortisone cream to help relieve the itching.

Unfortunately the majority of dealing with an exposure to poison oak is waiting for it to run the course.

Can you see the poison oak in this photo?

Can you see the poison oak in this photo?

How to Get Rid of the Plant

Once you have identified poison oak, if it can't be avoided, you are going to want to remove it carefully. This can be a tricky process because even if you use a product such as RoundUp to attempt to kill the plant, it can still cause the rash even after it is dead. The urushiol stays in the plant for years, even after the plant has died. The best way that I have found to remove the plant is by hand.

You can add an extra barrier of protection by applying a product like Ivy Block onto your skin underneath the long-sleeved shirt, long pants, and gloves that you will want to wear when removing this plant.

I use rubber gloves over a pair of tight-fitting work gloves to keep the oil of the plant from going through the fabric of the work gloves. I also use gloves and clothing, including shoes, that I don't mind throwing into the trash once the removal is complete. The urushiol can stay in clothing for quite a long time, sometimes even lasting through a wash in the machine. I throw everything I am wearing away.

You'll want to get as much of the plant as you can, including the roots, and you'll want to kill any of the roots that you aren't able to get. A couple of organic methods for killing the roots would be to use straight white vinegar or boiling water. You will want to mark the area and repeat the application for a few days to ensure that you have, in fact, killed the roots of the plant.

Never, EVER burn poison oak plants. Burning this plant will release the oil into the air and can infect anyone who breathes in or comes into contact with the smoke from the burning poison oak. Never add poison oak to your compost; it will more than likely start growing there or infect the rest of your compost. It is best to dispose of the plant in a heavy, double-bagged trash bag.

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

Questions & Answers

Question: Can the oil from poison oak on my skin spread to my bed?

Answer: Now that's an excellent question. My guess would be that once it has dried on your skin that it won't spread around on fabric or other items. If you lay down right after being exposed to poison oak or ivy, then it might be able to do that unless you shower first. That's my best guess from what I learned about poison oak and ivy.


Rachel L Alba from Every Day Cooking and Baking on February 08, 2016:

Hi Helena, I wish I saw this hub a couple of years ago. I came in contact with poison oak, thinking it was just a huge weed growing near the place I worked. I pulled it out and got poison oak all over my hands and arms. What a mess, not to mention how it felt. I also had poison ivy when I was a little girl on my face. I don't even remember how I got it, but I remember my little friends wouldn't play with me until it was gone. Thanks for sharing this information.

Blessings to you.

sehrm from Los Angeles on January 29, 2014:

Poison oak: the bane of my existence. I'd like to make one correction: since, as you said, urushiol is an oil and is thus not water-soluble, it will come off with a good soap. This is the point of soap (making oil water soluble), but you will need some heavy duty scrubbing to get the oil off every part of your body. Also, look to some plants that grow alongside poison oak for answers. In the right season, I've used mugwort or jewelweed to protect my skin from urushiol and it seems to have worked, although I am not willing to do a blind study on myself.

Helena Ricketts (author) from Indiana on September 03, 2012:

@ Maddie Thanks! I don't know what I was thinking. I caught this shoveling rock in flip flops and shorts. : / At least one good thing came out of it though!

@VirginiaLynne That's awful! I really do feel for her! I've been doing what is in the article and can say that for me, it has helped a LOT. I've been keeping a close eye on my dogs to make sure they don't get into it until I remove it. I definitely don't want to do this again, ever.

Virginia Kearney from United States on August 30, 2012:

A friend of mine just canceled their Labor Day party because she got poison oak. I'll pass your ideas on to her. We have lots of it around here and my husband watches out for it on hikes like a hawk. One thing he says is that you have to be careful of the stems in the winter. They are red and stick up and can also create a rash. Also--be very careful of dogs going through poison oak that is just off the trail. You can then get it from the dog rubbing on you or your clothes. I will certainly remember the alcohol trick. Voted up and shared.

Maddie Ruud from Oakland, CA on August 30, 2012:

I've had poison oak, and I used to get poison ivy on family camping trips regularly when I was a kid. Thank goodness, I haven't had it for years! Long pants really are a lifesaver.

Great information; I just wish you didn't have to go through so much pain to get those original pictures!