A client receiving morphine reports constipation to the nurse. What is the likely explanation for this symptom?

A. It indicates that the current dose is too low: Constipation is not an indicator of inadequate analgesia. Even therapeutic doses of morphine commonly cause gastrointestinal slowing regardless of pain control. B. It is a sign that the medication is not working: Constipation does not reflect the effectiveness of morphine for pain relief. The analgesic effect may be adequate, while opioid-induced bowel effects occur independently. C. It is an adverse effect of the morphine: Morphine binds to mu-opioid receptors in the gastrointestinal tract, reducing peristalsis and increasing water absorption from the stool. This predictable pharmacologic effect is a common adverse reaction requiring proactive bowel management. D. It is an interaction with another medication: While drug interactions can contribute to gastrointestinal symptoms, opioid-induced constipation is a direct pharmacologic effect of morphine itself and occurs even in the absence of other medications.