Medical Definition of loratadine
: a long-acting, nonsedating antihistamine drug C22H23ClN2O2 taken orally to relieve the symptoms of seasonal allergic rhinitis and chronic urticaria ◆Loratadine is an H1 antagonist that binds competitively with histamine to H1 receptors on cell membranes. It is marketed under the trademark Claritin.
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