A nurse is caring for a client who started the SSRI fluoxetine 3 days ago and now reports feeling agitated, with muscle tremors and a temperature of 39°C (102.2°F). Upon assessment, the nurse notes hyperreflexia, tremors, and diaphoresis. What is the nurse's best initial action?

Administer acetaminophen for the fever and continue to monitor the client.

increase the client's fluid intake to prevent dehydration and recheck vital signs in one hour.

Notify the provider immediately to evaluate for serotonin syndrome and initiate treatment.

Encourage the client to rest and provide a cooling blanket to reduce the fever