Topical application of
antihistamines commonly leads to sensitization for patients, but systemic administration of
antihistamines rarely induces allergic
hypersensitivity, which is mainly linked to
phenothiazine-derived and
piperazine-derived compounds. We report a 70-year-old woman whose medical history included
lichen planus, and who was referred by the dermatology department of our hospital for suspected
allergy to
corticosteroids. The reason for referral was that on the fourth day of treatment with
prednisone and
hydroxyzine, the patient presented a bilateral highly pruritic palmar
erythema that evolved to a generalized morbilliform
rash with subsequent complete desquamation. At a later time, she took
cetirizine for a cold, and developed palmar
erythema and desquamation. Skin tests (prick and intradermal tests) were performed with
steroids, and patch tests (read after 48 and 96 h) with
corticosteroids and
antihistamines. Controlled oral challenge tests were performed with
prednisone and with an alternative
antihistamine. Skin tests were negative for all
corticosteroids. Patch tests were negative for all
corticosteroids, but the
antihistamine test was positive for
hydroxyzine. Oral challenge with
prednisone and
dexchlorpheniramine was negative. The patient was diagnosed with cutaneous
drug eruption from
hydroxyzine and
cetirizine. We consider it is important to assess every patient whose skin condition worsens
after treatment with
antihistamines, especially
hydroxyzine, because it is known that
antihistamines are often not recognised as the culprit in cases of cutaneous eruption.