What is a common side effect associated with opioid use?

Opioid use is well-known for causing constipation as a common side effect. This occurs because opioids bind to receptors in the gastrointestinal (GI) tract, leading to decreased motility and slowing down the movement of food through the intestines. The impact on gastrointestinal function can result in harder stools and difficulty passing them, which characterizes constipation.

While nausea can also occur with opioid use, it's typically more variable between individuals based on their unique reactions to the medication. Diarrhea is generally less common; rather, opioids tend to cause the opposite effect due to their action on the GI tract. Headaches can happen for various reasons, but they are not a direct result of opioid use and are less characteristic than constipation. Thus, constipation stands out as the most predictable and commonly reported adverse effect associated with opioid medications.