In serotonin syndrome, which symptom indicates increased autonomic activity?

In serotonin syndrome, increased autonomic activity is characterized by symptoms that reflect heightened sympathetic nervous system activity. An increased heart rate is a direct manifestation of this autonomic stimulation, which can occur due to excessive serotonin levels in the central nervous system. The condition frequently presents with tachycardia, hypertension, hyperthermia, and other autonomic dysregulation symptoms, illustrating a state of heightened bodily response.

While dry skin may suggest other forms of autonomic dysfunction, it does not typically represent increased sympathetic activity. Weight gain is not associated with serotonin syndrome but rather with chronic conditions or long-term medication effects. Muscle cramps might be seen in serotonin syndrome due to neuromuscular excitability but do not signify increased autonomic activity. Thus, increased heart rate stands out as the most pertinent indication of heightened autonomic activity specifically in the context of serotonin syndrome.