Can taking a phenergan (promethazine) cause someone to be in an altered state?

Yes: Some significant possible adverse effects of Phenergan (promethazine) involving the central nervous system include catatonic states, confusion, delirium, disorientation, dizziness, drowsiness, euphoria, excitation, faintness, fatigue, hallucinations, hysteria, insomnia, lassitude, nervousness, nightmares, sedation, seizure, and somnolence. I am not sure of the individual frequencies of these side effects.