The nurse is preparing to administer diphenhydramine HCL, to a client with allergic rhinitis. Which desired effect describes the rationale for administering this medication?

Rationale: A. Histamine-1 antagonists cause the nasal mucosa to shrink: Shrinking of nasal mucosa is more closely associated with decongestants such as pseudoephedrine, not antihistamines. Antihistamines work by blocking histamine receptors to reduce allergic symptoms. B. This classification of drugs decreases gastric acid production: Reduction of gastric acid is the role of H2 receptor antagonists such as famotidine. Diphenhydramine is an H1 receptor antagonist, so this mechanism does not apply to allergic rhinitis treatment. C. These medications decrease upper airway inflammation: While antihistamines may indirectly reduce irritation, their primary effect is not anti-inflammatory. Corticosteroids are more effective in directly reducing inflammation in allergic conditions. D. Antihistamines decrease nasopharyngeal secretions: Diphenhydramine reduces histamine-mediated responses, which in turn decreases rhinorrhea, sneezing, and nasal secretions. This desired effect explains why it is given for allergic rhinitis.