History: A detailed history, both before and after patch
testing, is crucial in evaluating individuals with ACD. Potential causes of ACD
and the materials to which individuals are exposed should be patch tested.
Patients with ACD require a much more detailed history compared to those with
most other dermatologic disorders.
History is equally important after patch testing. Only history and
questioning can determine whether the materials to which a patient is allergic
are partly or wholly responsible for the current dermatitis. A positive patch
reaction may indicate only a sensitivity and not the cause of current
- Preexisting skin diseases
- Individuals with stasis dermatitis are at high risk for developing ACD to
materials and agents applied to the areas of stasis dermatitis and leg ulcers.
Neomycin is an important cause of ACD in these individuals because it is used
frequently despite the lack of documentation of its efficacy in the treatment
of stasis ulcers.
- Individuals with otitis externa frequently are allergic to topical neomycin
and topical corticosteroids.
- Individuals with pruritus ani and pruritus vulvae may become sensitized to
benzocaine and other medications applied to chronic pruritic processes.
- Women with lichen sclerosus et atrophicus frequently develop ACD,
complicating the severe chronic vulvar dermatosis. Patch testing these patients
may provide important information that can help in the management of
recalcitrant and difficult-to-manage dermatosis.
- Atopic dermatitis
- Patients with a history of atopic dermatitis are at increased risk for
developing nonspecific hand dermatitis and irritant contact dermatitis.
- Patients with a history of atopic dermatitis do not appear to be at an
increased risk for ACD, despite the wide range of topical medications and
moisturizers used by individuals with chronic atopic dermatitis.
- Patients with atopic dermatitis are at lower risk of ACD to poison ivy.
- Some European studies indicate that patients with atopic dermatitis may
have increased incidence of ACD to nickel.
- Individuals with ACD typically develop dermatitis (within a few days of
exposure) in areas that were exposed directly to the allergen. Certain
allergens (eg, neomycin) penetrate intact skin poorly, and the onset of
dermatitis may be delayed up to a week following exposure.
- A minimum of 10 days is required for individuals to develop specific
sensitivity to a new contactant.
- An individual who never has been sensitized to poison ivy may develop only
a mild dermatitis 2 weeks following the initial exposure but typically develops
severe dermatitis within 1-2 days of the second and subsequent exposures.
Remember that removing the poison ivy allergen from the skin is difficult, and
unless an individual washes exposed skin within 30 minutes of exposure, ACD
will develop. The hallmark of the diagnosis of poison ivy is linear dermatitic
- The possibility of an external cause of dermatitis always must be
considered if the dermatitis is linear or sharply defined. The immediate onset
of dermatitis following initial exposure to material suggests either a
cross-sensitization reaction, prior forgotten exposure to the substance, or
nonspecific irritant contact dermatitis provoked by the agent in question.
- Eyelid dermatitis: Individuals may develop dermatitis on eyelids and other
exposed skin following exposure to airborne allergens.
- Immediate reactions, ie, visible lesions developing less than 30 minutes
after exposure, indicate contact urticaria (not ACD), particularly if
urticarial in appearance and if associated with other symptoms such as distant
urticaria, wheezing, ophthalmedema, rhinorrhea, or anaphylaxis.
- Rubber latex currently is the most important source of allergic contact
urticaria (see Latex Allergy). The term hypoallergenic may refer to gloves that
do not contain sensitizing chemicals added to rubber latex but may not indicate
whether the gloves are rubber latex free. Some individuals may have delayed
specific contact sensitivity to rubber latex, but contact urticaria to rubber
latex is much more common than ACD to latex. Individuals with hand dermatitis,
hospital workers, children with spina bifida, and atopic individuals are at
increased risk of developing contact urticaria to rubber latex. Individuals may
have ACD to chemicals added to rubber gloves and have contact urticaria to
latex. Individuals wearing rubber gloves should be evaluated carefully for both
- Rare reports exist of immediate anaphylactic reactions to topical
antibiotics (eg, bacitracin).
- Occupational dermatitis: Contact dermatitis is 1 of the 10 leading
occupational illnesses. It may prevent individuals from working. The hands are
the sites exposed most intensely to contact allergens and irritants, both at
work and at home. The hands are crucial for performing many work-related tasks.
ACD in response to workplace materials may improve initially on weekends and
during holidays, but individuals with chronic dermatitis may not demonstrate
the classic history of weekend and holiday improvement. Irritant contact
dermatitis is more likely if multiple workers are affected in the workplace.
Most allergens rarely sensitize a high percentage of the population.
- Hobbies: Hobbies may be the source of ACD, eg, woodworking with exotic
tropical woods or processing film using color-developing chemicals that may
provoke cutaneous lesions of lichen planus from direct skin exposure.
- Medications: Self-prescribed and physician-prescribed medications are
important causes of ACD. The workplace nurse may dispense ineffective and
sensitizing topical preparations, such as Merthiolate, which may change a
simple abrasion into a severe case of ACD. Individuals may develop allergy to
preservatives in medications and/or to the active ingredients in topical
medications, especially neomycin and topical corticosteroids.
- Iatrogenic adverse effects: Chronic use of systemic corticosteroids to
treat ACD may produce severe morbidity. Individuals with ACD should not receive
chronic systemic corticosteroids or immunosuppressives, unless extensive patch
testing and evaluation have failed to identify remedial causes of the severe
dermatitis. Chronic widespread use of potent topical corticosteroids may
produce local skin atrophy and systemic adverse effects.