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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.
Hyperexcitability and abnormal movements have been reported in patients following a single administration of promethazine HCl (promethazine hydrochloride) . Consideration should be given to the discontinuation of promethazine HCl (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.
Read the Promethazine HCl (promethazine hydrochloride) Side Effects Center for a complete guide to possible side effects
CNS Depressants- Promethazine hydrochloride tablets may increase, prolong, or intensify the sedative action of other central-nervous-system depressants, such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic anti-depressants, and tranquilizers; therefore, such agents should be avoided or administered in reduced dosage to patients receiving promethazine HCl. When given concomitantly with promethazine hydrochloride tablets, the dose of barbiturates should be reduced by at least one-half, and the dose of narcotics should be reduced by one-quarter to one-half. Dosage must be individualized. Excessive amounts of promethazine HCl (promethazine hydrochloride) relative to a narcotic may lead to restlessness and motor hyperactivity in the patient with pain; these symptoms usually disappear with adequate control of the pain.
Epinephrine- Because of the potential for promethazine to reverse epinephrine's vasopressor effect, epinephrine should NOT be used to treat hypotension associated with promethazine hydrochloride tablets overdose.
Anticholinergics- Concomitant use of other agents with anticholinergic properties should be undertaken with caution. Monoamine Oxidase Inhibitors (MAOI) - Drug interactions, including an increased incidence of extrapyramidal effects, have been reported when some MAOI and phenothiazines are used concomitantly. This possibility should be considered with promethazine hydrochloride tablets.
Drug/laboratory test interactions
Diagnostic pregnancy tests based on immunological reactions between HCG and anti-HCG may result in false-negative or false-positive interpretations.
Glucose Tolerance Test
An increase in blood glucose has been reported in patients receiving promethazine HCl (promethazine hydrochloride) .
Last reviewed on RxList: 6/13/2008
This monograph has been modified to include the generic and brand name in many instances.
Additional Promethazine HCl Information
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