urushiolia

Urushiolia is a form of contact dermatitis caused by urushiol, the oily allergenic compound found in plants of the Toxicodendron genus, including poison ivy (Toxicodendron radicans), poison oak (Toxicodendron diversilobum or related species), and poison sumac (Toxicodendron vernix, depending on region), as well as in lacquer-producing trees such as the lacquer tree Toxicodendron vernicifluum. The condition arises when urushiol penetrates the skin and binds to proteins, forming hapten-protein complexes that are recognized by the immune system, triggering a delayed-type hypersensitivity reaction known as type IV hypersensitivity. Sensitization often occurs after an initial exposure, with subsequent encounters producing dermatitis within about 12 to 72 hours.

Symptoms typically include intense itching, redness, swelling, and a vesicular or blistering rash that may ooze and crust. The rash is not contagious through fluids from the blisters, but urushiol residue on skin, clothing, or objects can transfer to other areas until cleaned. Diagnosis is usually clinical, based on history of exposure and characteristic rash; patch testing can confirm sensitivity in unclear cases or for occupational assessment.

Treatment focuses on removing the source of urushiol and controlling inflammation. Immediate washing of exposed skin with soap and water after contact can reduce severity. For established dermatitis, topical corticosteroids are commonly used; more severe cases may require systemic corticosteroids. Antihistamines can help alleviate itching, and antibiotics may be needed if secondary infection occurs.

Prevention centers on avoiding contact with urushiol-containing plants, prompt washing of skin and contaminated items, washing or changing contaminated clothing and footwear, and using protective clothing or barrier methods when exposure is likely. Avoid burning urushiol-containing plants, as inhalation of smoke can cause serious respiratory irritation. Prognosis is generally good, with most cases resolving within one to three weeks, though extensive or severe reactions can take longer.