Allergic Contact Dermatitis Clinical Presentation

Acute allergic contact dermatitis (AACD) usually will develop within 12 to 24 hours of contact with a plant containing a particular allergen to which an individual is sensitive, but can take as long as 72 hours to develop. The patient nearly always presents with an itchy rash that is visible on exposed skin surfaces as a papulovesicular eruption in patches, lines, or scratch marks. The rash can include erythema, vesiculation, weeping, pruritis, and vesicles coalesced into bulae. While it is commonly believed that the allergen can be spread from person to person, or scratched out of the lesion, this is not the case, as the allergen fixes in the skin within a few minutes. Before the allergen is set in the skin, it is possible, however, to spread the allergen away from the initial site, leading to streak or scratch marks. A secondary

Table 26.2. Selected plants associated with phytodermatitits.

Allergic contact dermatitis

Irritant contact dermatitis

African poison ivy (Smodingium argutum)

Barberry (Berberis)

Bramble (Rubus)

Cashew (Anacardium occidentale)

Buttercups (Ranunculus)



Daffodil (Narcissus), tulip, and

hyacinth (Hyacinthus) bulbs

Dandelion (Taraxacum)

Garlic and onion (Allium)

Ginkgo tree (Ginkgo biloba)

Hot peppers (Capsicum)

Hot peppers (Capsicum)

Lady's slipper (Cypripedium)

Japanese lacquer tree (Toxicodendron verniciflua)


Celery (Apium)

Liverworts (Frullania)


Mango (Mangifera indica)

Fig (Ficus carica)

Marigold (Tagetes)

Gas plant (Dictamnus)

Marking nut tree (Semecarpus anacardium)

Parsley (Petroselinum)

Parsnip (Pastinaca)

Poison ivy (Toxicodendron radicans, T. rydberrgii)

Queen Anne's Lace (Daucus carota)

Poison oak (T diversilobum, T. toxicarium)

Rue (Ruta graveolens)


Poison sumac (T. vernix)

Castor bean (Ricinus communis)

Ragweed (Ambrosia)

Wild feverfew, congress grass, or carrot


weed (Parthenium hysterophorus)


Garlic (Allium)

Wormwood (Artemisia)

Kiwi fruit

Stinging nettle (Urtica dioica)


infection can result from scratching, and an individual without plant contact can develop AACD from allergen present on clothing or equipment. If exposure occurs through clothing or on most body surfaces, the lesions can produce diffuse edema. This form of dermatitis typically will clear within 10 days but can last up to several weeks. Unlike photodermatitis, AACD rarely leaves behind any scars or changes in pigmentation. With repeated exposure to the same allergen, the AACD can become chronic. If it does remain acute, symptoms will usually worsen with each subsequent exposure. However, as one reaches older adulthood, sensitivity appears to decrease (35-40).

The short onset of symptoms associated with AACD lends to an easier diagnosis of the trigger than with chronic allergic contact dermatitis, which is characterized by similar skin lesions that are persistent and not itchy. There also tends to be more redness associated with chronic dermatitis, however the causative plant triggers are no different (36,41).

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