Safety of antihistamines in the treatment of allergic rhinitis in elderly patients.

Elderly patients may be more susceptible than younger persons to the sedating and anticholinergic effects of first-generation antihistamines. Second-generation antihistamines, such as loratadine, astemizole, and terfenadine, cause minimal sedation and little if any impairment in cognitive and psychomotor activity in healthy nonelderly patients. Although less extensively studied in elderly patients, it is probable that second-generation antihistamines are also less likely to induce the adverse central nervous system effects in older patients that are characteristic of the first-generation antihistamines. Toxic effects to the cardiovascular system, an issue of greater concern among elderly patients who may have subclinical heart disease, has not been observed with first-generation antihistamines. Among the second-generation antihistamines, however, astemizole and terfenadine, but not loratadine, can cause serious cardiovascular adverse effects, including death, when taken in high doses or coadministered with ketoconazole, itraconazole, or macrolide antibiotics.