Which of the following is not a common side effect of opioids?

Opioids are well-known for several common side effects due to their mechanism of action in the central nervous system. Nausea, constipation, and respiratory depression are frequently observed effects when these medications are used.

Nausea occurs because opioids can trigger the area postrema, which is involved in the vomiting reflex. Constipation is a very common side effect as opioids bind to receptors in the gastrointestinal tract, reducing peristalsis and slowing bowel movements. Respiratory depression is another significant and potentially dangerous side effect, as opioids depress the neurons in the brain that control breathing, leading to decreased respiratory rate and depth.

Insomnia, while it can be a result of pain or other underlying issues, is not a direct effect of opioids. Rather, opioids can sometimes induce drowsiness or sedation. In many cases, they may actually help with sleep in patients who are experiencing pain, making insomnia less likely to be considered a common side effect, particularly when compared to the well-documented effects of nausea, constipation, and respiratory depression. This distinction helps clarify why insomnia is viewed as less characteristic of opioid use when assessing potential side effects.