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DermatologicalICD-10: L23.7Up to 50 million Americans are affected by poison ivy rash annually

Poison Ivy Rash (Contact Dermatitis)

Poison ivy rash is an allergic contact dermatitis caused by urushiol, an oily resin found in the leaves, stems, and roots of poison ivy, poison oak, and poison sumac plants. Approximately 85% of the population is allergic to urushiol, making it one of the most common causes of allergic contact dermatitis. The rash typically appears within 12-72 hours of contact and can range from mild redness to severe blistering that lasts 2-3 weeks.

Symptoms

Intense itching at the site of contact
Red, swollen skin in a streaky or patchy pattern
Small blisters that may ooze fluid
Larger blisters (bullae) in severe reactions
Crusting of blisters as they begin to heal
Swelling of the affected area
Rash spreading to new areas (from residual urushiol on skin, clothing, or pets)

Causes

  • Direct contact with urushiol resin from poison ivy, poison oak, or poison sumac
  • Indirect contact through contaminated clothing, tools, pet fur, or other objects
  • Inhaling smoke from burning poison ivy plants (can cause severe lung irritation)
  • Contact with urushiol that has remained active on surfaces for months to years

Risk Factors

  • Outdoor activities such as hiking, gardening, camping, or forestry work
  • Living or working in areas where poison ivy grows (most of North America)
  • Inability to identify poison ivy plants
  • Failure to wear protective clothing in wooded or overgrown areas
  • Having pets that roam through areas with poison ivy

Diagnosis

  • Clinical diagnosis based on characteristic rash pattern and history of plant exposure
  • Physical examination of the linear or streaky distribution of the rash
  • Patch testing if the cause of contact dermatitis is unclear

Treatment

  • Wash the skin immediately with soap and water (or rubbing alcohol) to remove urushiol
  • Calamine lotion or colloidal oatmeal baths to relieve itching
  • Over-the-counter hydrocortisone cream for mild cases
  • Oral antihistamines (diphenhydramine, cetirizine) for itch relief
  • Prescription oral corticosteroids (prednisone) tapered over 2-3 weeks for severe or widespread rash
  • Cool compresses to reduce inflammation and soothe itching

Prevention

  • Learn to identify poison ivy ('leaves of three, let it be')
  • Wear long sleeves, pants, and gloves when working in areas where poison ivy grows
  • Apply barrier creams (bentoquatam) before potential exposure
  • Wash clothing, tools, and pet fur that may have contacted poison ivy
  • Remove poison ivy plants from your yard using protective equipment

When to See a Doctor

  • The rash covers a large area of the body or affects the face, eyes, or genitals
  • You develop severe swelling, widespread blisters, or signs of infection
  • You inhaled smoke from burning poison ivy and have difficulty breathing

Frequently Asked Questions

Related Conditions

Acne Vulgaris

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Cellulitis

Infectious

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