When using hydroxyzine, what should patients be cautioned about regarding its effects?

Hydroxyzine is an antihistamine commonly used for its sedative and anti-anxiety properties. One of its primary effects is sedation, which is why patients should be cautioned about drowsiness as a potential side effect. This is particularly important for individuals who may need to operate machinery, drive, or engage in activities that require alertness, as the drowsiness caused by hydroxyzine can impair these capabilities. The sedative effect is a significant aspect of its pharmacological profile and is one reason why it is sometimes prescribed in the context of anxiety, sleep disorders, or preoperative sedation.

The other effects mentioned in the question, such as elevated blood pressure, diarrhea, and increased anxiety, are not typical concerns associated with hydroxyzine and therefore do not apply in this context. Thus, the emphasis on drowsiness as a cautionary point is rightly prioritized when discussing the use of hydroxyzine with patients.