Nervous System - CNS depression, particularly respiratory depression, and to a lesser extent circulatory depression; light-headedness, dizziness, sedation, euphoria, dysphoria, headache, transient hallucination, disorientation, visual disturbances, and convulsions.
Cardiovascular - Tachycardia, bradycardia, palpitation, faintness, syncope, orthostatic hypotension (common to narcotic analgesics).
Gastrointestinal - Nausea, vomiting, constipation, and biliary tract spasm. Patients with chronic ulcerative colitis may experience increased colonic motility; in patients with acute ulcerative colitis, toxic dilation has been reported.
Genitourinary - Oliguria, urinary retention; antidiuretic effect has been reported (common to narcotic analgesics).
Allergic - Infrequent pruritus, giant urticaria, angioneurotic edema, and laryngeal edema.
Other - Flushing of the face, sweating and pruritus (due to opiate-induced histamine release); weakness.
Central Nervous System - Drowsiness is the most prominent CNS effect of this drug. Sedation, somnolence, blurred vision, dizziness; confusion, disorientation, and extrapyramidal symptoms such as oculogyric crisis, torticollis, and tongue protrusion; lassitude, tinnitus, incoordination, fatigue, euphoria, nervousness, diplopia, insomnia, tremors, convulsive seizures, excitation, catatonic-like states, hysteria. Hallucinations have also been reported.
Cardiovascular - Increased or decreased blood pressure, tachycardia, bradycardia, faintness.
Dermatologic - Dermatitis, photosensitivity, urticaria.
Hematologic - Leukopenia, thrombocytopenia, thrombocytopenic purpura, agranulocytosis.
Gastrointestinal - Dry mouth, nausea, vomiting, jaundice.
Respiratory - Asthma, nasal stuffiness, respiratory depression (potentially fatal) and apnea (potentially fatal). (See WARNINGS-Promethazine; Respiratory Depression.)
Other - Angioneurotic edema. Neuroleptic malignant syndrome (potentially fatal) has also been reported. (See WARNINGS-Promethazine; Neuroleptic Malignant Syndrome.)
Paradoxical Reactions - Hyperexcitability and abnormal movements have been reported in patients following a single administration of promethazine hydrochloride. Consideration should be given to the discontinuation of promethazine hydrochloride and to the use of other drugs if these reactions occur. Respiratory depression, nightmares, delirium, and agitated behavior have also been reported in some of these patients.