Evaluation: tests usually not needed
A diagnosis of contact dermatitis usually requires nothing more than findings in the patient’s history and physical exam. If a fungal infection is suspected, use a potassium hydroxide (KOH) preparation to look for hyphae or spores (see page 854 in this issue). Patch testing—placing common antigens on the patient’s skin and observing for reactions—is used to confirm the diagnosis of contact dermatitis and to determine the offending agent.
In this case, neither test was necessary or warranted because the history and physical exam led to a clear diagnosis that was treatable without having to analyze the chemicals in the perfume.
Treatment: remove the irritant, stop the swelling
Whether this is irritant or allergic contact dermatitis, the first line of treatment is to stop further exposure to the offending substance. A mid- to high-potency topical corticosteroid is recommended to stopping the inflammatory process (level of evidence [LOE]=5). (For an explanation of evidence-based medicine ratings, see page 000.) Ointments are more potent and particularly useful when the affected skin is dry and scaly.
Oral steroids are often used for severe local dermatitis, such as that caused by poison ivy (LOE=5). Topical tacrolimus ointment 0.1% is a more expensive option for the treatment of allergic contact dermatitis induced by nickel (LOE=2b).1 Oral H1 blocking sedating anti-histamines (such as diphenhydramine and hydroxyzine) provide relief from itching and help with sleep. Sedating antihistamines may be more effective for itching, but are probably inadvisable for persons who must drive or operate machinery. Newer nonsedating anti-histamines are an option when sedating agents should be avoided.
Conclusion of visit
The patient was given 0.1% triamcinolone ointment (a generic mid-potency steroid) to apply 2 to 3 times a day to the affected areas. She did not want any oral medications for the itching, but understood that diphenhydramine is available without a prescription if needed. She planned to give the perfume away and understood it was now on her list of items to avoid. Her physician explained her underlying eczema and what could be done to prevent rashes.