Review the patient's history for evidence of glaucoma, prostatic hyperplasia, or asthma
Inquire about urinary pattern, particularly in male patients over the age of 55 who may be developing prostatic hyperplasia
Assess cardiac and respiratory status
Assess for signs and symptoms of urinary dysfunction, including retention, dysuria, and altered frequency
Note complete blood count (CBC) during therapy
Assess the patient's work environment and consider whether drowsiness will affect safety and work performance
Warn patients to avoid driving a motor vehicle and performing other dangerous activities if drowsiness occurs or until stabilized on the drug
Advise patients to avoid alcohol and other central nervous system depressants
Encourage patients to take drugs as prescribed. Notify a health care provider if confusion or hypotension occurs
Teach patients on prophylaxis for motion sickness to take diphenhydramine at least 30 minutes before the offending event and also before meals and at bedtime during the event
Inform breastfeeding mothers that small amounts of drugs pass into breast milk. Because children are more susceptible to the side effects of antihistamines (e.g., unusual excitement or irritability), breastfeeding is not recommended while using these drugs