How to Tell the Difference Between Poison Ivy and Poison Oak

Do These Rhymes Sound Familiar?

“Leaves of three, let it be”
“Berries white, run in fright”
“Hairy vine, no friend of mine”

They remind us how to spot Poison Ivy and Poison Oak, of course. As a child in summer camp, our counselors had us memorize this rhyme, and it’s served its’ purpose throughout the years. My kids now know this rhyme by heart and pay attention to it when out playing.

When outdoor summer fun is on the mind, few remember to consider the risk of poison ivy, poison oak, and poison sumac to their health. Itchy red rashes, swelling, even blistering- an innocent hike in the forest can have very uncomfortable consequences if you don’t know what to avoid. Within as little as 12 hours of contact, these plants can cause an itchy, red, and peeling rash that can last for weeks. When it comes to poison ivy or poison oak,  it’s not the leaves themselves that can cause you to itch for days, it’s an oil coating the leaves called Urushiol.

Here’s how to tell the difference between poison ivy and poison oak:

Common characteristics of both poison ivy and poison oak:

  • Both are found in nearly every state in the U.S.
  • Both grows at altitudes below 5,000ft
  • Both are deciduous
  • Both grow as a bush or vine
  • Neither stem have thorns
  • Both usually grow clusters of three ‘leaflets’
  • 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 in both poison ivy and poison oak
  • Both have inconspicuous white spring flowers which usually produce clusters of small white blueberry-sized berries that turn red in late summer
  • Both produce a rash-inducing oil called Urushiol ( the bad stuff)
  • Both can be toxic to humans but are harmless to animals
  • All parts of both plants contain the toxins (leaflets, stems, and roots)

The most tell-tale characteristics of poison ivy are

  • “Hairy” vines
  • Though Poison Ivy is not really an ivy, it’s often viney growth pattern can resemble ivy
  • Smooth or subtly toothed almond shaped leaflets that are sometimes irregularly lobed


Distinct characteristics of Poison Oak include:

  • Leaf shape resembles an oak leaf (but it’s not a member of the oak family)
  • Leaflets are duller green and usually more distinctly lobed or toothed than poison ivy
  • Mature leaflets are typically duller green than young ones
  • Leaflets have hairs on both sides, unlike poison ivy


Even a slight brush against theses plants can result in a skin reaction. The toxin is easily transferred from one surface to another and will remain potent for years if not thoroughly cleaned (imagine your exposed dog running through your house!). Also, symptoms can take 24-48 hours or even up to a week to show up, particularly if its your first exposure!  We recommend that you keep an eye out for these tell-tale signs to avoid contact!

Though rarely leading to serious or life-threatening sickness, contact with these plants can cause severe allergic reaction which is characterized by the following symptoms and more:

  • Severe swelling and redness
  • Fever
  • Blisters and crusting skin
  • Difficulty breathing or swallowing

Please seek immediate medical care if you experience any of these symptoms.

Here at AFC Urgent Care Danbury we’re committed to providing fast and affordable care to patients 1 year or older. We also accept most insurances and offer low rates for uninsured patients. For more information, visit us at either of our convenient locations at 2 Main Street or 100 Mill Plain Road in Danbury, CT.

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