Discontinue treatment after symptoms have resolved & reinitiate upon reappearance for seasonal allergic rhinitis. Avoid coadministration w/ P-gp inhibitors eg, ketoconazole, erythromycin, cyclosporine, ritonavir or diltiazem in patients w/ moderate or severe renal impairment. May affect ability to drive & use machines. Avoid use during pregnancy. Lactation. Not to be used in childn <6 yr weighing <20 kg. Renally & hepatically impaired childn.