Constipation has recently become a problem for a school-age girl. She is healthy except for seasonal allergies that are being treated with antihistamines. What should the nurse suspect caused the constipation?

A) Diet
B) Allergies
C) Antihistamines
D) Emotional factors

Constipation may be associated with drugs such as antihistamines, antacids, diuretics, opioids, antiepileptics, and iron. Because this is the only known change in her habits, the addition of antihistamines is most likely the cause of the diarrhea. With a change in bowel habits, the role of any recently prescribed medications should be assessed.