What types of medications are documented to result in constipation?

• A. Narcotics
• B. Laxatives
• C. Antibiotics
• D. Proton pump inhibitors

Answer: (A)

Opioids slow gut movement by binding to mu receptors in the gastrointestinal tract, which reduces propulsive peristalsis and increases fluid absorption. This combination leads to drier, harder stools and fewer bowel movements, making opioid-induced constipation a very common and predictable effect with narcotic analgesics. Because this effect is well-documented and occurs across various opioids and doses, narcotics are the best choice when identifying medications that cause constipation.

Laxatives, by contrast, are used to treat or prevent constipation rather than cause it. Antibiotics more often disrupt the gut flora and lead to diarrhea rather than constipation. Proton pump inhibitors can have a range of GI side effects, but constipation is not the hallmark or most consistent outcome associated with them.