When evaluating a patient who has just experienced a seizure, the physician should first verify that the patient has normal vital signs and adequate oxygenation and that there is no further seizure activity. There is no standardized algorithm for the evaluation of every patient with a first seizure. Instead, a careful history and physical examination should determine imaging and laboratory testing decisions. The history should initially focus on determining whether a seizure actually occurred and evaluating the circumstances and characteristics of the event. The behaviors of the patient during the event and evidence of partial onset may be important in identifying a specific form of epilepsy. A history of trauma or symptoms of infection (e.g., stiff neck, fever, headache) also helps direct the evaluation. The patient should be asked about medication, illicit drug, and alcohol use. A history of neurologic or developmental disorders or a family history of epilepsy may help narrow the differential diagnosis. The physical examination should include a thorough neurologic and mental status evaluation. In older children and adults, a serum prolactin measurement, if obtained within 10 to 20 minutes of the event, is useful in differentiating a generalized tonic-clonic seizure or complex partial seizure from a pseudoseizure. The sensitivity of an elevated prolactin level is 60 percent for generalized tonic-clonic seizures and 46 percent for complex partial seizures.