A client taking fluoxetine calls the clinic to report onset of new symptoms. From the list of symptoms below, identify the ones that would lead the nurse to believe the client may be experiencing serotonin syndrome.

Rationale: A. Irritability: Irritability is a neuropsychiatric symptom that can occur in serotonin syndrome due to excessive serotonergic activity in the central nervous system. It often presents alongside agitation, confusion, and anxiety, reflecting overstimulation of serotonin pathways. B. Insomnia: Insomnia is a common side effect of SSRIs like fluoxetine but is not specific to serotonin syndrome. It can occur independently due to the activating effects of the medication on central nervous system arousal without indicating a toxic serotonergic state. C. Decreased libido: Decreased libido is a well-documented adverse effect of SSRIs caused by altered serotonin modulation of sexual function. However, it is a chronic medication effect and not an acute indicator of serotonin syndrome. D. Muscle spasms: Muscle rigidity, tremor, and spontaneous muscle spasms are hallmark physical manifestations of serotonin syndrome. These occur due to excessive serotonergic stimulation in the spinal cord and neuromuscular junction, leading to abnormal muscle contractions. E. Hypertension: Hypertension is a sign of autonomic dysfunction that can accompany serotonin syndrome, along with tachycardia, hyperthermia, and diaphoresis. It reflects overstimulation of sympathetic pathways due to excessive serotonin activity.