What is the definition or description of: phenergan (promethazine) overdose?

Death possible but: Overdose signs/symptoms range from mild depression of the central nervous system and cardiovascular system to profound hypotension, respiratory depression, and unconsciousness, and sudden death. Other reported reactions include hyperreflexia, hypertonia, ataxia, athetosis, and extensor-plantar reflexes. Ref: http://www.rxlist.com/phenergan-drug/overdosage-contraindications.htm