What is the primary side effect associated with opioid use?

Opioid use is most commonly associated with constipation as a primary side effect. This occurs because opioids bind to specific receptors in the gastrointestinal tract, leading to decreased peristalsis and increased absorption of fluids from the intestinal contents. As a result, bowel movements can become infrequent and difficult, leading to the discomfort often reported by patients receiving opioid therapy.

The other options, such as increased energy, insomnia, and hyperactivity, do not reflect typical effects of opioids, which are primarily sedative in nature. Opioids often produce drowsiness and relaxation rather than increased activity or wakefulness. This highlights the importance of monitoring patients for constipation and implementing preventive measures when prescribing opioids, as it can significantly impact their quality of life.