Diseases & Conditions

Allergic Contact Dermatitis - Poison Ivy, Poison Oak, and Poison Sumac Dermatitis


Overview, Causes, & Risk Factors

Exposure to poison ivy, poison oak, or poison sumac plants results in an allergic reaction of the skin to the plant oil called urushiol.

What is going on in the body?

Not everyone is allergic to urushiol. If the uroshiol from the plant touches the skin of someone who is allergic to it, it starts a reaction that results in blisters. This reaction is known as an allergic contact dermatitis. The outbreak of the reaction starts at the spot on the skin where the urushiol touched it. Once the urushiol has been thoroughly washed off the skin, no further spread of the dermatitis can occur.

Original sites of contact may continue to break out with blisters over the next several days. Portions of the skin that had the most contact usually react first, followed by areas of skin that had less contact with the plant. This often gives people the impression that the dermatitis is contagious, which it is not.

What are the causes and risks of the condition?

Skin contact with urushiol from poison ivy, poison oak, or poison sumac plants causes the allergic contact dermatitis.


Symptoms & Signs

What are the signs and symptoms of the condition?

Symptoms of poison ivy, poison oak, or poison sumac dermatitis include red welts and blisters on exposed areas of skin. These areas may have burning and itching that ranges from mild to severe.


Diagnosis & Tests

How is the condition diagnosed?

Often the person diagnoses the allergic contact dermatitis himself or herself by noticing the itchy blisters and recalling plant contact. Otherwise, the healthcare provider makes the diagnosis by examining the rash and asking about possible urushiol contact.


Prevention & Expectations

What can be done to prevent the condition?

To prevent an allergic reaction to urushiol, individuals should avoid contact with poison ivy, poison oak, or poison sumac plants. Long sleeves and long pants provide a barrier to the urushiol. It's also important to wash both the skin and clothing thoroughly after any potential contact. A skin cream is available for people who are especially sensitive to urushiol and can't avoid the plants.

What are the long-term effects of the condition?

There are usually no long-term effects from exposure to poison ivy, poison oak, or poison sumac. Repeated bouts of the allergic contact dermatitis can become more severe. The allergic reaction may be particularly bothersome when it involves large areas of the skin surface, the face, or the mouth.

What are the risks to others?

The allergic contact dermatitis can only be spread to other individuals if someone comes in contact with the urushiol on the person's skin before it has been washed off. Special care needs to be taken when handling clothing, jewelry, shoes, tools, or animals that have come into contact with any part of the plant. Contact with a person's blisters or fluid from broken blisters does not spread the dermatitis.


Treatment & Monitoring

What are the treatments for the condition?

Treatments for poison ivy, poison oak, or poison sumac dermatitis range from home remedies to prescription medications. Common treatment measures include the following:

  • cool compresses soaked with tap water, baking soda water, or Epsom salts to temporarily relieve symptoms
  • tepid baths in water containing products made from ground oatmeal
  • topical corticosteroids, such as hydrocortisone or betamethasone, or triamcinolone
  • antihistamines such as diphenhydramine to relieve itching
  • oral corticosteroids, such as prednisone or methylprednisolone, for severe cases
  • What are the side effects of the treatments?

    Oral corticosteroids may cause mood disturbance, increased appetite, increased blood pressure, elevated blood glucose, and bone or skin thinning.

    What happens after treatment for the condition?

    Recuperation from poison ivy, poison oak, or poison sumac dermatitis should occur in one to two weeks, although repeat occurrences occasionally happen with repeat exposure. Reexposure to urushiol may occur, for example, after handling camping gear, golf clubs, clothing, or pet fur that was originally in contact with the plant.

    How is the condition monitored?

    Any new or worsening symptoms should be reported to the healthcare provider.


    Attribution

    Author:Lynn West, MD
    Date Written:
    Editor:Crist, Gayle P., MS, BA
    Edit Date:02/28/01
    Reviewer:Eileen McLaughlin, RN, BSN
    Date Reviewed:07/27/01