Final answer:
It is crucial to assess for a history of urinary retention before administering an antihistamine, as these medications can worsen the condition due to their anticholinergic effects. Antihistamines mitigate allergy symptoms by blocking histamine receptors and are also used to treat conditions such as insomnia and motion sickness.
Step-by-step explanation:
Prior to administering an antihistamine to a patient, it is most important for the nurse to assess the patient for a history of urinary retention. Antihistamines prevent mast cells from releasing histamines, which can alleviate unpleasant allergy symptoms such as watery, itchy eyes, swollen tissues, and sneezing. However, they can also exacerbate conditions like urinary retention due to their anticholinergic effects, making the assessment of urinary retention history crucial before administration. Conditions like chronic urticaria, motion sickness, and insomnia may actually be indications for antihistamine use, as these medications are often effective in treating these issues.
Moreover, antihistamines work by binding to histamine H1 receptors in mast cells and other tissues in the body. They can be used to treat allergic reactions in the nose and are also used for conditions like insomnia and motion sickness. Therefore, when a patient experiences severe allergy symptoms, it's likely due to increased activity of certain leukocytes like mast cells, which release histamines. These symptoms can often be managed with antihistamines provided there is no contraindication such as urinary retention.