Poison Ivy (Toxicodendron Dermatitis)

Poison Ivy Rash

Overview

Poison ivy dermatitis is an allergic contact dermatitis caused by urushiol, an oily resin found in poison ivy, poison oak, and poison sumac plants. It is the most common cause of allergic contact dermatitis in North America. The rash typically appears 12-72 hours after exposure and is characterized by intensely itchy, red, streaky blisters.

Key Symptoms

• Intensely itchy, red, streaky rash in linear or irregular patterns
• Blisters (vesicles and bullae) that may weep clear fluid
• Swelling and redness in the area of contact
• Rash often appears in streaks or lines corresponding to plant contact
• New areas may appear over several days (not from spreading fluid, but delayed absorption)
• Severe reactions may involve facial swelling or widespread blistering

Affected Areas

Hands, Arms, Legs, Face, Any exposed skin

Care Instructions

1. Wash all exposed skin, clothing, tools, and pets with soap and water as soon as possible after exposure.
2. Apply cool compresses and calamine lotion to soothe itching.
3. Over-the-counter hydrocortisone cream and oral antihistamines can help mild cases.
4. See a doctor for severe reactions — oral corticosteroids (typically a 2-3 week taper) may be needed.
5. Do not pop blisters; blister fluid does not spread the rash.
6. Learn to identify and avoid poison ivy, oak, and sumac plants ("Leaves of three, let it be").

Medical Disclaimer: This information is for educational purposes only and does not replace professional medical advice. Always consult a qualified dermatologist for diagnosis and treatment.

Prevalence: Very common; approximately 50-75% of the U.S. population is sensitized to urushiol