Which of the following are common symptoms of serotonin syndrome?

Serotonin syndrome is characterized by an excess of serotonin in the brain, often resulting from the use of certain medications or drug interactions that increase serotonin levels. The common symptoms associated with serotonin syndrome typically include alterations in mental status, which can manifest as agitation, confusion, hallucinations, and other neuropsychiatric symptoms. Agitation reflects a heightened state of arousal and restlessness, while hallucinations involve sensory experiences that are not present, indicating significant alterations in perception.

The other options, while they may describe symptoms related to different conditions or side effects of various medications, do not correlate with the hallmark symptoms of serotonin syndrome. For example, fatigue and weight gain are more often associated with conditions like depression or certain medications that affect metabolism. Dry mouth and constipation can result from various medications but are not specific to serotonin syndrome. Blurred vision and confusion might indicate other medical issues, but confusion is usually present in serotonin syndrome, while blurred vision does not typically characterize that syndrome.

Overall, the presence of agitation and hallucinations directly aligns with the clinical picture of serotonin syndrome, making it the correct choice among the symptoms listed.