From the Guidelines
Phenergan (promethazine) can cause several side effects, including drowsiness, dizziness, dry mouth, blurred vision, and constipation, as well as more serious side effects like confusion, irregular heartbeat, tremors, and difficulty urinating, as reported in a study published in Gastroenterology 1.
Common Side Effects
- Drowsiness
- Dizziness
- Dry mouth
- Blurred vision
- Constipation These side effects are due to promethazine's antihistamine, sedative, anti-emetic, and anticholinergic effects, as described in a study on the use of promethazine for sedation during endoscopic procedures 1.
Serious Side Effects
- Confusion
- Irregular heartbeat
- Tremors
- Difficulty urinating It is essential to note that promethazine can cause significant sedation, which is why it's often used to help with sleep or as an anti-nausea medication before surgery, as mentioned in a study on the management of postoperative nausea and vomiting 1.
Special Considerations
- Paradoxical reaction with restlessness or excitability, particularly in children
- Long-term use can lead to tolerance
- Interaction with other medications that cause drowsiness, including alcohol, potentially increasing sedation If you experience severe side effects like difficulty breathing, seizures, or uncontrolled movements, seek immediate medical attention, as advised in the study on the use of promethazine for sedation during endoscopic procedures 1. Always take Phenergan as prescribed and discuss any concerns with your healthcare provider.
From the FDA Drug Label
ADVERSE REACTIONS 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). The side effects of Phenergan (promethazine) include:
- Central Nervous System: drowsiness, sedation, somnolence, blurred vision, dizziness, confusion, disorientation, extrapyramidal symptoms, lassitude, tinnitus, incoordination, fatigue, euphoria, nervousness, diplopia, insomnia, tremors, convulsive seizures, excitation, catatonic-like states, hysteria, hallucinations
- 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, apnea 2
From the Research
Side Effects of Phenergan (Promethazine)
- Drowsiness: All subjects in a study reported drowsiness as a result of the promethazine injection 3
- Nervous excitation: Most subjects in a study reported nervous excitation as a result of the promethazine injection 3
- Dry mouth: Most subjects in a study reported dry mouth as a result of the promethazine injection 3
- Fatigue: Most subjects in a study reported fatigue as a result of the promethazine injection 3
- Excessive anxiety: Two subjects in a study reported excessive anxiety as a result of the promethazine injection 3
- Dizziness: One subject in a study reported dizziness as a result of the promethazine injection 3
- Sedation: Opioid side effects, including sedation, were reported when meperidine was combined with promethazine 4
- Nausea: Opioid side effects, including nausea, were reported when meperidine was combined with promethazine 4
- Limb-threatening adverse effects: Rare but serious limb-threatening adverse effects have been associated with injectable promethazine after extravasation or inadvertent intra-arterial injection 5
- Impairment and dysregulation of the central and autonomic nervous systems: Promethazine has a well-documented history of undesired side effects relating to impairment and dysregulation of the central and autonomic nervous systems, such as sedation, extrapyramidal symptoms, dystonia, impairment of psychomotor function, neuroleptic malignant syndrome, and hypotension 6
- Side-effects: More side-effects were seen in the promethazine-treated group compared to the ondansetron-treated group in a clinical trial 7