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If the foreign body can be removed, antibiotic treatment should be reserved for
secondary infections. Tetanus prophylaxis is required for these injuries.
Many plants contain irritants that cause reactions through their chemical or
physical properties. For example, members of the family Araceae (e.g., Dieffenbachia or
dumbcane) possess bundles of needle-like calcium oxalate crystals in their cells (
raphides) that cause intense pain and itching through their microinvasive properties.
Often children learn this through an unfortunate tasting experiment. These substances
affect most people and are not dependent upon an individual being "allergic" to the
offending agent. The reaction generally happens within seconds to minutes of the
exposure compared to "allergic" reactions that usually develop 20-30 minutes after
contact. The two cannot be differentiated by inspection alone. Treatment consists of
general cleaning with cool compresses for comfort and analgesics as necessary. Most
reactions are self-limited but can be quite painful for 12-24 hours. Intense itching can be
relieved with antihistamines.
Contaminated eyes should be copiously irrigated. A cycloplegic like
scopolamine 0.25% drops (see Wilderness Eye Injuries) may greatly relieve pain along
with the use of artificial tears. Patching is not helpful unless a foreign body cannot be
removed.
B. Chemical Injury and Treatment
1. Allergic dermatitis:
This phenomenon occurs after previous sensitization to some allergen. These agents are
usually in the form of a hapten that combines with skin proteins to form an antigen. This
is a cellular (type IV) reaction mediated by t-lymphocytes. In those individuals who tend
to be atopic, the reaction can be eczematous.
In the United States the family Anacardiaceae containing poison ivy
(Toxicodendron radicans) and poison oak (T. diversilobum) causes more dermatitis than
any other plant, household or industrial chemical. The offending agents here are various
catechols. The severity of reaction to this family depends on the size and thickness of the
cornified skin exposed, and the dose of toxin received following contact a cutaneous
response occurs in 12-24 hours. This latent period can be helpful in determining the
mechanism of reaction. Initially an area of erythema develops usually with some edema.
During the next 24 hours vesicles or bullae develop containing a nonallergic serous fluid
that does not spread the dermatitis, contrary to popular belief. Exudation may be marked
and itching is intense. After several days crusting develops and resolution occurs in 10-14
days barring complications. Previously affected sites distant from the currently affected
area may flare as well.
Cutaneous penetration takes about 10 minutes. Therefore if exposure is
immediately recognized prompt washing may reduce the severity or prevent a reaction. .
Washing with water is recommended, but avoid soaps as they remove protective oils
from the skin. Apply organic solvents like alcohol carefully to avoid spreading the agent.
Both topical and oral steroids are maximally effective during this period. Generally
"dose-packs" are inadequate in both dose and duration often leading to "rebound"
dermatitis. Prednisone should be started with an oral dose of 0.75-1 mg/kg/day (usually
60-80 mg) for 14 days and then tapered by 10 mg every other day to prevent recurrence.
