Abstract Interferon-α (IFN-α) is a cytokine used as a first line of defense against diseases such as cancer and hepatitis C. However, reports indicate that its effectiveness as a treatment is countered by central nervous system (CNS) disruptions in patients. Our work explored the possibility that it may also cause long-term behavioral disruptions by chronicling the behavioral and physiological disturbances associated with a single injection of vehicle, 10, 100, or 1000 units of IFN-α in male Sprague–Dawley rats ( n = 5/dose). Following 1 day of locomotor baseline collection, we monitored sickness behaviors (ptosis, piloerection, lethargy, and sleep), food and water intake, body weight, temperature, and motor activity. Observations were recorded 4 days prior to and 4 days following the IFN-α injection. Temperature and sickness behaviors were recorded three times daily at 9:00, 15:00, and 21:00 h, and all other indices, once daily. On the injection day, temperature values were highest in the animals receiving the 10-unit IFN-α dose 15 min and 13 h post-injection. In the case of sickness behaviors, a significant increase was observed in piloerection in all IFN-α groups at each time point measured, while the scores of the rats in the vehicle condition remained unchanged between pre- and post-injection days. Analyses of overall sickness behaviors during morning and night observation periods indicated increased scores in all IFN-α groups following injection. Cumulatively, these data suggest that a single IFN-α exposure may elicit long-term behavioral disruptions and that its consequences should be thoroughly investigated for its use in clinical populations.