3 Tips for Poison Ivy and Other Rashes

Get the truth about the three-leafed scoundrel. Learn how it spreads and how to make it better.

Rob Lamberts, MD
5-minute read
Episode #7

Last time we talked about swimmer's ear, a common summer malady. In today’s articIe am going to talk about poison ivy, a spring and summer skin condition that can make the season a little less blissful. 

3 Tips for Dealing With Poison Ivy

  1. If you get contact dermatitis, wash everything
  2. For mild rashes, use hydrocortisone
  3. See your doctor for bad rashes, or ones that you aren’t sure about

But let's start at the beginning. 

What Is Contact Dermatitis?

The skin problem I am covering in this podcast is called contact dermatitis. The word dermatitis means: “something is messed up with the skin.” Rashes are sometimes difficult to identify. The only way to diagnose what causes a rash is to look at it and hear the story of how it got there. There is no rash-o-meter that you can put on it to tell you what it is, so it’s not uncommon for rashes to befuddle doctors. When this happens, they usually diagnose it as dermatitis. That is cheating, really, because the patient already knows that there is something messed up with their skin. I’ll let you in on a common doctor trick: using a Latin or Greek word is a good way to sound smart when you don’t have a clue.

Contact dermatitis is a rash that happens because of contact with certain substances. Fortunately, it’s usually not very hard to identify. The most notorious cause of contact dermatitis is the dreaded poison ivy.

What Is Poison Ivy?

Poison ivy (and its partners in crime, poison oak and poison sumac) is a plant that has oil on its leaves. Some people develop an allergy to this oil, which results in the typical poison ivy rash. There are a number of other less common substances that can also cause contact dermatitis, including Neomycin (a common skin antibiotic), nickel (which is present in many belt-buckles) and something called Balsam of Peru. I don’t know what Balsam of Peru is, but I advise avoiding it if you can.

Contrary to what I learned as a kid, there is no difference between the rash caused by poison ivy and those of poison oak and sumac. The typical rash from contact dermatitis is red, raised, sometimes blistering, and very itchy. It also occurs in crops or patches on the skin rather than in a generalized rash. That is because the rash only happens where the skin has contacted the offending oil.

How Do Rashes--Like Poison Ivy--Spread?

That is a really important point when dealing with contact dermatitis. Most people believe that it can be spread by scratching and spreading the fluid in the blisters. That is not true. The only way the rash can spread is if the oil from the plant spreads to new parts of the skin. There are several ways for this to happen:

  • The person doesn’t believe in personal hygiene or has a religious objection to using soap. Soap makes oil dissolve in water and wash down the drain. Soap is your friend.

  • They enjoy the rash so much, they go back and touch more plants to maximize their fun.

  • The towels, shirts, coats, and bed linens get some of the oil on them and so spread it to different body parts. Watch bands and eye glasses can also carry the oil.

  • Bowser the dog rolled around in a field of the plants and is spreading the joy with his affection.

When Do Rashes Show Up?

The problem is that the rash shows up 12 to 24 hours after the contact. That means that people will repeatedly expose themselves to the oil before they know and regret it. A lot of exposure can happen in the window of time before the rash shows up.


Please note that all content here is strictly for informational purposes only. This content does not substitute any medical advice, and does not replace any medical judgment or reasoning by your own personal health provider. Please always seek a licensed physician in your area regarding all health related questions and issues.