Which of the following symptoms is least likely to occur with opioid-induced constipation?

Opioid-induced constipation is a common side effect of opioid medications due to their action on the gastrointestinal (GI) tract, which decreases motility and causes harder stool formation. Among the symptoms typically associated with this condition, unintended weight gain is least likely to occur.

Opioids frequently lead to symptoms such as abdominal cramping, nausea, and difficulty passing stool. Abdominal cramping may arise from increased pressure in the intestines or associated discomfort from bowel obstruction or distention due to constipation. Nausea is also a prevalent complication of opioid use, often related to their central nervous system effects, which can influence both gastrointestinal motility and sensory perception in the GI tract. Difficulty passing stool is a direct consequence of the slowed transit time and the increased hardness of the stool, characteristic of opioid-induced constipation.

In contrast, unintended weight gain is not typically associated with opioid-induced constipation. While prolonged constipation may lead to some transient fluid retention or minor dietary changes, the overall trend with opioid use tends to favor weight loss or stasis due to decreased appetite and reduced physical activity. Therefore, it is the symptom least aligned with the expected effects of opioid-induced constipation.