Which adverse effects are commonly associated with cholinesterase inhibitors?

• A. Gastrointestinal symptoms such as nausea, vomiting, diarrhea
• B. Renal colic
• C. Hepatotoxicity
• D. Seizures

Answer: (A)

Cholinesterase inhibitors raise acetylcholine levels, boosting parasympathetic activity. In the gut, acetylcholine stimulates smooth muscle contraction and secretions, leading to increased motility and secretory activity. That combination produces common gastrointestinal symptoms like nausea, vomiting, and diarrhea, making these effects the most consistently observed adverse effects with these medications. Other options don’t fit as well: renal colic isn’t a typical consequence of cholinergic overactivity, hepatotoxicity is not a common issue with standard cholinesterase inhibitors, and seizures are not typically seen at therapeutic doses (they may occur with overdose or severe cholinergic crisis). So the GI disturbances best reflect the usual adverse effect profile mediated by enhanced muscarinic stimulation in the GI tract.