What are the typical physical exam findings for contact dermatitis from poison ivy?

From the Guidelines

Physical exam findings for poison ivy contact dermatitis typically include linear or streaked erythematous (red) rashes with papules, vesicles, and bullae in areas that contacted the plant, as a result of the allergic compound urushiol, affecting approximately 50% to 75% of individuals 1. The rash is often intensely pruritic (itchy) and may show signs of excoriation from scratching.

• Key characteristics of the rash include:
  • Redness
  • Papules
  • Vesicles
  • Itching
• The extent and severity of symptoms are proportional to the area and duration of exposure, with symptoms typically starting within days of exposure and lasting up to 3 weeks 1. Edema (swelling) is common, especially in sensitive areas like the face or genitals.
• The distribution of the rash follows exposure patterns, with lesions appearing in a time-dependent manner over 1-3 days, not all at once. Weeping or crusting may be present in more severe cases.
• The rash results from a delayed type IV hypersensitivity reaction to urushiol oil in the plant, with symptoms appearing 12-48 hours after exposure in previously sensitized individuals, while first-time exposures may take 1-2 weeks to develop symptoms 1. The diagnosis is primarily clinical, based on the characteristic appearance and distribution of the rash along with a history of potential exposure to poison ivy.

From the Research

Physical Exam Findings for Contact Dermatitis from Poison Ivy

The typical physical exam findings for contact dermatitis from poison ivy include:

• Erythematous and pruritic skin lesions that occur after contact with the plant 2
• Visible borders with erythema and scaling 2
• Itching and discomfort 2
• Acute cases may involve a dramatic flare with erythema, vesicles, and bullae 2
• Chronic cases may involve lichen with cracks and fissures 2
• Lesions can be linear in configuration, especially if the plant came into contact with the skin in a brushing or scratching manner 3
• Vesicles and flaccid bullae on erythematous bases 3
• Erythema and swelling 3

Characteristics of Poison Ivy Dermatitis

Poison ivy dermatitis is an acute self-limiting problem of two or three weeks' duration that can cause significant discomfort 4

• It is almost always a form of allergic contact dermatitis 5
• The eruptions usually have a characteristic streak-or-line-like appearance 5
• They usually clear within one to three weeks unless there is continued exposure to the allergen 5