Final answer:
Monitoring for constipation is an important nursing action for clients on hydrate sedative-hypnotic medication.
Step-by-step explanation:
The nursing action that indicates an understanding of the major side effect of hydrate sedative-hypnotic medication is B. Monitoring for constipation. Hydrate sedative-hypnotics, such as benzodiazepines, can cause constipation as a common side effect due to their effects on the central nervous system and smooth muscle relaxation.
Constipation can occur because the medication slows down the speed of digestion and decreases the contractions of the intestines, leading to difficulty in passing stools. It is important for nurses to monitor clients on this medication for constipation and provide appropriate interventions, such as increasing fluid and fiber intake, to prevent complications.