A client who is newly diagnosed with diabetes insipidus is receiving a synthetic vasopressin intravenously. Which side effect of vasopressin reported by the client should the nurse report to the healthcare provider?

A) Worsening headache: This option is correct. Vasopressin, also known as antidiuretic hormone (ADH), acts to increase water reabsorption in the kidneys, thereby reducing urine output. However, excessive administration of vasopressin can lead to vasoconstriction, which may result in increased intracranial pressure and subsequent headaches. Therefore, worsening headache can be indicative of vasopressin overdose or adverse effects, and it should be promptly reported to the healthcare provider for evaluation and appropriate management. B) Polyuria: Polyuria, or excessive urine output, is the opposite effect of vasopressin. While diabetes insipidus is characterized by polyuria due to insufficient ADH secretion or renal responsiveness to ADH, administering vasopressin should decrease urine output. Therefore, polyuria would not be expected as a side effect of vasopressin administration. C) Polydipsia: Polydipsia, or excessive thirst, is also a symptom of diabetes insipidus but is not typically associated with vasopressin administration. Vasopressin functions to decrease urine output and, consequently, reduce thirst. Therefore, polydipsia would not be expected as a side effect of vasopressin administration. D) Low urine specific gravity: Vasopressin administration is expected to increase urine specific gravity by promoting water reabsorption in the kidneys, leading to more concentrated urine. Therefore, low urine specific gravity would not be an expected side effect of vasopressin administration.