Allergy to dexchlorpheniramine. Study of a case.

Dexchlorpheniramine (DH) is a classical or first generation antihistamine belonging to the ethanolamine group. Adverse effects related to these antihistamines are frequent, but the hypersensitivity reactions described in the literature since 1940 are exceptional. We report the case of a 32-year-old woman who experienced two episodes of akathisia secondary to intravenous (i.v.) dexchlorpheniramine administration for a possible hypersensitivity reaction to local anesthetics. Allergological study consisted of the following tests: skin prick tests with routine allergens, with a negative result; skin prick and intradermal tests with local anesthetics and DH, with a positive result to DH in the intradermal skin test (+ +); serum specific IgE, which was within normal levels; histamine release test with DH with a negative result, and the basophil activation test (BAT) with local anesthetics and DH, which was positive for DH and weakly positive to Lidocaine. BAT is proving to be a highly useful tool in the field of drug allergy, with a higher sensitivity and specificity than other in vitro tests. Because it avoids the need for provocation tests, this is especially important in drug-induced allergic reactions in which in vivo tests are repeatedly negative despite a clear clinical history.