Which of the following is NOT a common symptom of dehydration?

The correct answer is excessive sweating, as it is not commonly associated with dehydration but rather indicates fluid loss. During dehydration, the body has a decreased availability of fluids, which can often lead to reduced sweating as a protective mechanism against further fluid loss. The body tends to conserve water and would therefore exhibit diminished sweating rather than excessive.

In contrast, increased thirst is a well-recognized symptom of dehydration, serving as a natural response urging the body to seek out fluids. Dry mucous membranes can occur because less fluid in the body leads to less moisture in tissues, which is typical in dehydrated states. Frequent headaches can also be a symptom of dehydration, as insufficient hydration may lead to headaches due to decreased blood volume and changes in electrolyte balance. Each of these symptoms—thirst, dry mucous membranes, and headaches—reflect the body's responses to a decrease in hydration status.