A nurse is reinforcing teaching to a graduating nurse about fluid volume deficit. Which of the following concepts about water balance should the nurse explain to the graduating nurse?

A. Photophobia: Antihistamines are not typically associated with photophobia. Common side effects include dry mouth and drowsiness, but not increased sensitivity to light.

B. Increased blood pressure: Antihistamines do not commonly cause increased blood pressure. They are more likely to lead to side effects like dry mouth, drowsiness, and blurred vision rather than affecting blood pressure significantly.

C. Diarrhea: Diarrhea is not a usual side effect of antihistamines. These medications are more likely to cause constipation rather than diarrhea.

D. Dry mouth: Dry mouth is a common adverse effect of many antihistamines. This occurs due to their anticholinergic effects, which decrease saliva production and lead to dry mouth.

A. The intracellular space contains most of the body's water: While it is true that the intracellular space holds the majority of the body's water, this statement does not specifically relate to the concept of fluid volume deficit or how the body responds to it.

B. A fluid volume deficit inhibits baroreceptors: In fact, fluid volume deficit activates baroreceptors due to reduced blood pressure, leading to compensatory mechanisms like increased heart rate and vasoconstriction to maintain blood pressure.

C. When the body loses water, the intravascular space experiences the water loss: This statement accurately describes the process during fluid volume deficit. The intravascular space loses water, leading to decreased blood volume, which can result in symptoms like hypotension and reduced tissue perfusion.

D. A negative fluid balance occurs when the body takes in more water than the body needs: This statement is incorrect; a negative fluid balance occurs when the body loses more water than it takes in, leading to dehydration or fluid volume deficit.