Summary about Disease
Poison oak dermatitis is an allergic skin reaction resulting from contact with urushiol, an oily resin found in poison oak plants. This contact triggers an immune response, causing an itchy, blistering rash. The severity of the reaction varies depending on individual sensitivity and the amount of urushiol exposure.
Symptoms
Itching
Redness
Swelling
Blisters (small or large, sometimes filled with clear fluid)
Hives
Burning sensation
Rash typically appears in streaks or patches where the plant contacted the skin.
Causes
The rash is caused by urushiol, an oil found in poison oak. Direct contact with the plant is the most common cause, but the oil can also be transferred by:
Touching contaminated objects (clothing, tools, pets).
Inhaling smoke from burning poison oak (rare, but can cause severe systemic reactions).
Medicine Used
Topical Corticosteroids: Creams or ointments like hydrocortisone (for mild cases). Stronger prescription corticosteroids may be needed for more severe reactions.
Oral Corticosteroids: Prednisone (prescription) may be prescribed for widespread or severe rashes.
Antihistamines: To relieve itching (e.g., diphenhydramine, loratadine).
Calamine Lotion: To soothe the skin and dry oozing blisters.
Topical barrier creams: Contain bentoquatam which can block urushiol absorption if applied before exposure.
Is Communicable
The rash itself is not contagious. You cannot spread the rash to other people by touching the blisters or the affected skin. However, urushiol can be spread if it's still on the skin, clothing, or other objects.
Precautions
Learn to identify poison oak.
Wear long sleeves, long pants, gloves, and closed shoes when in areas where poison oak may grow.
Apply barrier creams containing bentoquatam before potential exposure.
Immediately wash exposed skin with soap and water (within 10 minutes of contact is ideal). Special poison ivy washes are also available.
Wash contaminated clothing and tools separately with hot water and detergent.
Avoid burning poison oak, as the smoke can cause a reaction.
Consider having pets that roam in potentially contaminated areas bathed regularly.
How long does an outbreak last?
The rash typically lasts from 1 to 3 weeks. Mild cases may resolve within a week, while more severe reactions can take several weeks to heal.
How is it diagnosed?
Diagnosis is usually based on a physical examination and the person's history of exposure. No specific lab tests are typically needed. The appearance of the rash, along with knowledge of potential exposure to poison oak, is usually sufficient for diagnosis.
Timeline of Symptoms
Within hours to days (typically 12-72 hours) after exposure: Redness and itching begin.
1-7 days: Blisters form.
1-3 weeks: Rash gradually resolves, with blisters drying and scabbing over. The exact timeline depends on the severity of the exposure and individual sensitivity.
Important Considerations
Urushiol can remain active on surfaces for a long time (even years).
Repeated exposure can lead to more severe reactions.
Seek medical attention if the rash is severe, widespread, near the eyes or mouth, or accompanied by fever or difficulty breathing.
Do not scratch the rash, as this can increase the risk of infection.
It is a myth that the fluid in the blisters spreads the rash.