Poison Ivy: How to Treat that Itchy Rash

Days are getting longer, the temperatures are rising, and stay-at-home restrictions are easing. Because of this, many people are spending extra time outside. Hikers are climbing, mountain bikers are biking, and gardeners are gardening. Sadly, these actions usually are not risk-free in the case of your pores and skin. Relying on the place you reside, chances are you’ll inadvertently have a detailed encounter with poison oak, poison ivy, or poison sumac and find yourself an annoying, unpleasant, and really itchy rash. 

Why does poison ivy trigger itchy rashes?

Crops of the genus Toxicodendron (beforehand labeled because the genus Rhus) may cause an itchy rash in many individuals who are available in contact with them. Essentially the most generally encountered crops of this genus embody poison ivy, poison oak, and poison sumac.

Though all three of those crops may cause the rash, it’s generally known as poison ivy dermatitis, notably east of the Rockies. It’s sometimes called poison oak within the Western US. The medical title for the situation is Toxicodendron dermatitis or Rhus dermatitis. For ease of studying, the time period poison ivy will likely be used as a substitute of itemizing all three crops repeatedly.

The rash is a kind of allergic contact dermatitis (a traditional sort IV cell-mediated hypersensitivity response). It’s triggered when the allergens in oily sap resin, urushiol, is transferred to the pores and skin. These allergens are small and in a position to shortly penetrate the outer layer of the pores and skin known as the dermis. The presence of those allergens on the pores and skin triggers the immune response that ends in the rash.

You will need to know that urushiol is present in all elements of the crops, together with the leaves, stems, and roots. It will probably even be present in lifeless branches. And, it may be transferred to garments, the fur of pets, and different objects similar to gardening instruments that are available in contact with the crops. Switch of the resin from these objects to human pores and skin may also set off the immune response.

The epidemiology of poison ivy dermatitis

Urushiol is extremely allergenic and many individuals are sensitized to it. In reality, it’s estimated that ~50 million folks yearly require medical remedy after being uncovered to urushiol. Though anybody could be affected, sure professionals are at specific threat, together with,

  • firefighters
  • forestry employees
  • farmers
  • gardeners.

Poison ivy impacts kids and adults of all ages, though there’s some proof that the allergic response can decreases with age if individuals are not repeatedly uncovered. Additionally, it impacts all ethnicities and pores and skin sorts.

Within the U.S., poison ivy is extra frequent east of the Rockies and poison oak west of the Rockies. Poison sumac is discovered primarily within the southeastern a part of the nation.

Identification of the plant: the important thing to avoiding contact

Crops within the genus Toxicodendron generally encountered by individuals who benefit from the outside. Subsequently, you will need to discover ways to determine them. Their look can fluctuate relying on quite a lot of components, together with:

  • development cycle of the plant
  • area of the nation
  • season of the 12 months
  • local weather

The outdated adage “leaves of three, allow them to be” could be a useful technique to bear in mind find out how to differentiate poison ivy and poison oak from different crops which are protected to the touch.

1. Poison ivy

The poison ivy plant has leaves that develop in teams of three. The leaves are pointed on the tip and the center leaf could also be barely bigger than the opposite two aspect leaves. They’re inexperienced in colour within the spring however flip reddish to orange in colour within the fall. Poison ivy can develop as each a vine and a shrub. It might have a small cluster of white berries within the spring that may final all through the winter.

Images courtesy of U.S. Division of Agriculture – Submitted by Creator

2. Poison oak

Poison oak is extra sometimes discovered as a shrub, though it will probably typically be discovered as a vine. Its leaves, which vaguely resemble oak leaves, additionally happen in teams of three just like poison ivy. The leaves are inexperienced within the spring however flip orange to purple within the fall. Poison oak flowers could also be yellow or inexperienced and have greenish-yellow or white berries.

poison oak for poison ivy dermatitis story
Images courtesy of U.S. Division of Agriculture – Submitted by Creator

3. Poison Sumac

Poison sumac is much less just like the earlier varieties in that it’s a woody shrub with stems that include 7 -13 leaves organized in pairs. The berries additionally fluctuate and could also be pale yellow or cream-colored. Poison primarily grows in moist swampy or boggy areas.

poison sumac for poison ivy dermatitis story
Images courtesy of U.S. Division of Agriculture – Submitted by Creator

Reference for plant ID and images):

The poison ivy dermatitis rash 

After being uncovered to the urushiol throughout the oily sap of the plant, a purple rash might seem inside a number of hours, particularly in case you’ve had poison ivy dermatitis earlier than. In beforehand unexposed people, it might take as much as 2 or 3 weeks to develop the rash.

The rash seems as purple, intensely itchy bumps or fluid-filled vesicles sometimes organized in a attribute linear or streak-like sample figuring out the place the plant contacted the pores and skin. If contact from the oil is a results of touching a bit of clothes or, touching a pet that was romping within the woods and consequently had oil on its fur, the rash might seem extra unfold out.


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If not promptly eliminated, the oil resin could be unfold to different areas of the physique by scratching. As well as, the rash might seem like spreading over time as a result of the eruptions will happen first within the areas of most intense publicity to the allergens and later in areas with much less intense publicity.

The rash itself will not be contagious. This isn’t an an infection, it’s an allergic response.

If left untreated, a poison ivy rash might final for a number of weeks. Those that have beforehand suffered from the rash are inclined to heal in a number of days. Those that have by no means had the rash appear to take longer to heal.


poison ivy dermatitis
Poison ivy dermatitis. (Photograph compliments of the American Academy of Dermatology Nationwide Library of Dermatologic Instructing Slides)

Poison ivy prevention and remedy

1. Prevention

As is the case for a lot of situations, prevention is the perfect remedy:

  • Keep away from the plant if doable and discover ways to determine poison ivy in all of its seasonal and geographic variations. Bear in mind: “leaves of three, let or not it’s.”
  • Put on protecting clothes when gardening or climbing: excessive socks, lengthy sleeves, and pants.
  • The usage of barrier lotions to forestall poison ivy rash is controversial. These topical preparations are sometimes utilized previous to publicity in an try to forestall the rash. A discount of reactivity was seen in a small examine with a 5% quaternion-18 bentonite lotion (bentoquatam). 

2. Take away the resin as quickly as doable after publicity

Though the rash itself will not be contagious, spreading the oil from one particular person to a different is definitely doable if the oil will not be eliminated.

  • Wash the uncovered space with delicate cleaning soap and water to take away any remnant oil resin out of your pores and skin as quickly as doable. Make sure you clear beneath the fingernails to take away any resin which will stay beneath the nails.
  • Wash all objects which will have are available in contact with the plant or its oils together with clothes, patio furnishings, gardening instruments, gardening gloves, golf golf equipment, and even your pets. The oil doesn’t have to come back straight from the plant to trigger a response.

3. A gentle case of poison ivy dermatitis with dwelling treatments

  • Over-the-counter hydrocortisone cream utilized twice day by day might relieve the itch and decrease the response.
  • An oral antihistamine may additionally relieve the itch.
  • Apply calamine lotion to small blisters and oozing pores and skin to assist dry out the rash.
  • Epsom salt soaks may additionally assist dry out the rash.
  • Don’t open blisters as this will likely predispose the pores and skin to an infection.
  • Cool compresses utilized to itchy areas could also be comforting.

If the rash is widespread or extreme, impacts the face or genitals, if blisters are oozing pus, or if fever develops, search medical consideration instantly.

4. Medical therapies for the poison ivy rash

  • Topical Corticosteroid Remedy: excessive efficiency corticosteroid preparations utilized straight on the rash is the mainstay of remedy for rhus dermatitis. To keep away from the event of  pores and skin atrophy, the prolonged use of those excessive efficiency preparations must be prevented on sure areas similar to: 
      • the face
      • genitals,
      • pores and skin folds of the armpits and groin
  • Systemic corticosteroid remedy: Sufferers with extreme or widespread illness, or with a rash that includes the face or genitals, might profit from oral steroid remedy. Though there isn’t a customary dosing, scientific expertise means that poison ivy might rebound when too in need of a course is taken (similar to a 6-day dose pack of methylprednisolone).  A excessive dose (1 mg/kg/day as much as a most beginning dose of 60 mg) of oral prednisone remedy given over 2 – 3 weeks can dramatically enhance poison ivy signs. For sufferers who can not take oral treatment, or can not adjust to the dosing schedule, intramuscular injections are one other remedy choice.
  • Antibiotics could also be crucial if bacterial an infection of the underlying rash is suspected.

If it’s not poison ivy what else may or not it’s?

  • An allergic contact dermatitis from a special form of plant: Rashes just like the one attributable to the genus Toxicodendron can be attributable to different crops.  Crops within the genus Asteraceae, which embody the flowering crops: daisies, sunflowers, dandelions, and asters may also trigger an identical pores and skin eruption. Crops within the genera Alliaceae (garlic), Allium (onion), and Myrtaceae (tea tree), amongst others, may also trigger related rashes. 
  • An allergic contact dermatitis from one thing apart from a plant: Allergic contact dermatitis can be attributable to allergens that aren’t crops. Nickel and gold, metals sometimes present in jewellery, for instance, are frequent causes of allergic contact dermatitis. 
  • Phototoxic reactions which will seem as purple rashes with or with out blistering might happen in response to publicity to photosensitizing crops and ultraviolet publicity. The commonest crops to trigger a lot of these reactions embody these within the genus Rutaceae (lemons and limes) and Umbelliferae (celery, wild parsnip, and parsley.) In contrast to poison ivy, these reactions will solely seem on sun-exposed pores and skin.

Poison ivy dermatitis: the underside line

It’s greatest to keep away from contact with the Toxicodendron crops that trigger this annoying rash. However in case you can’t or didn’t, transfer shortly to take away any resin in your pores and skin by washing with cleaning soap and water. If the rash erupts anyway (and it’s more likely to), strive dwelling treatments first. However search medical take care of extra critical instances.


See extra articles by Fayne Frey, MD


Initially printed on Might 17, 2020.  Up to date by the creator and republished on June 3, 2021.

Fayne Frey, MD

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Fayne Frey, M.D., is a board-certified scientific and surgical dermatologist training in West Nyack, New York, the place she specializes within the prognosis and remedy of pores and skin most cancers. She is a nationally acknowledged knowledgeable within the effectiveness and formulation of over-the-counter skincare merchandise.

She is a frequent speaker in lots of venues the place she captivates audiences together with her wry observations relating to the skincare business. She has consulted for quite a few media retailers, together with NBC, USA At the moment, and, the Huffington Submit. and has additionally shared her experience on each cable and main TV retailers.

Dr. Frey is the Founding father of, an academic skincare data and product choice service web site that clarifies and simplifies the overwhelming selection of efficient, protected and reasonably priced merchandise encountered within the skincare aisles.

Dr. Frey is a graduate of the Weill Cornell Medical Faculty and is a fellow of each the American Academy of Dermatology and the American Society for Dermatologic Surgical procedure.

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