Can promethazine be used to treat nausea?

From the Guidelines

Yes, promethazine can be used to treat nausea and vomiting, as it works by blocking histamine H1 receptors and has anticholinergic properties that help reduce nausea signals in the brain. The typical adult dose is 12.5 to 25 mg taken orally every 4-6 hours as needed, with a maximum daily dose of 100 mg 1. For children, dosing is weight-based and should be determined by a healthcare provider. Promethazine is available in tablet, syrup, and injectable forms. When taking promethazine, be aware that it may cause drowsiness, so avoid driving or operating machinery until you know how it affects you. Other common side effects include dry mouth, blurred vision, and constipation.

Key Considerations

• Promethazine should be used with caution in elderly patients and those with certain medical conditions like glaucoma, urinary retention, or severe heart or liver disease 1.
• The clinical effects of promethazine are evident within 5 minutes of intravenous administration, with a duration of action of 4 to 6 hours, and a plasma half-life of 9 to 16 hours 1.
• Promethazine has been investigated as an adjunct for sedation during minor surgical and endoscopic procedures, and has been used for the management of allergic reactions and anaphylaxis, as treatment of postoperative nausea and vomiting, and as an adjuvant for postoperative pain and sedation 1.

Administration and Dosage

• The usual dose of promethazine is 12.5 to 25 mg intravenously, infused slowly (25 mg/min) to minimize the risk of hypotension 1.
• A total dose of 25–100 mg may be used as an adjuvant to narcotics and benzodiazepines 1.
• For breakthrough treatment of chemotherapy-induced nausea and vomiting, promethazine can be used at a dose of 12.5-25 mg PO or IV every 4 hours 1.

Comparison with Other Antiemetics

• Promethazine is a phenothiazine antipsychotic that reduces nausea and vomiting by inhibiting dopamine receptors in the brain, but its use has not been studied in gastroparesis or compared prospectively with other anti-emetics 1.
• Other antiemetic agents, such as 5-HT3 receptor antagonists (e.g., ondansetron, granisetron) and neurokinin (NK-1) receptor antagonists (e.g., aprepitant, tradipitant), may also be effective in treating nausea and vomiting, but their use should be determined based on individual patient needs and medical history 1.

From the FDA Drug Label

For control of nausea and vomiting, the usual adult dose is 12. 5 to 25 mg, not to be repeated more frequently than every four hours. The average effective dose of promethazine hydrochloride for the active therapy of nausea and vomiting in children or adults is 25 mg 12.5- to 25-mg doses may be repeated, as necessary, at 4- to 6-hour intervals.

Yes, promethazine can be used to treat nausea, with a usual adult dose of 12.5 to 25 mg, not to be repeated more frequently than every four hours 2 3.

From the Research

Efficacy of Promethazine in Treating Nausea

• Promethazine has been shown to be effective in relieving nausea and vomiting, with studies indicating that low-dose intravenous promethazine (6.25 or 12.5 mg) can be as effective as intravenous ondansetron 4 mg 4.
• A review of promethazine's therapeutic uses and toxicity also supports its use as an antiemetic agent, particularly in the emergency department setting 5.
• Another study found that promethazine was effective in treating nausea and vomiting in hospitalized elderly patients, with a starting dose of 6.25 mg IV promethazine being as effective as higher doses and having fewer adverse drug reactions 6.

Safety Considerations

• While promethazine can be an effective antiemetic, its use must be approached with caution due to the risk of serious adverse effects, such as vascular damage upon intravenous administration 5, 7.
• Promethazine has also been associated with sedation, akathisia, and other adverse effects, particularly at higher doses 7.
• A case report highlighted the risk of acute orofacial dystonia associated with promethazine treatment, particularly in older patients 8.

Comparison with Other Antiemetic Agents

• Promethazine has been compared to other antiemetic agents, such as ondansetron, droperidol, prochlorperazine, and metoclopramide, with varying results 4, 7.
• Ondansetron has been shown to be as effective as promethazine in relieving nausea and vomiting, without the associated sedation and akathisia 4, 7.