Promethazine
Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026
A first-generation phenothiazine antihistamine with antiemetic, sedative, and anticholinergic properties. Promethazine is used for prevention and treatment of nausea and vomiting from various causes, motion sickness, allergic conditions, and as a pre- and postoperative sedative adjunct.
Exploratory record, not a reviewed medical publication.
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This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.
What the research says.
A quick, data-only summary. The full evidence, dosing, and sources are below.
A first-generation phenothiazine antihistamine with antiemetic, sedative, and anticholinergic properties. NutriStack rates the supporting evidence as strong. Common adult dosing is 12.5–25 mg every 4–6 hours as needed (as prescribed by your physician), though a prescriber sets the actual dose. This profile indexes 10 sources.
- Pronounced sedation and drowsiness
- Dry mouth
- Blurred vision
- Children under 2 years of age (risk of fatal respiratory depression)
- Known hypersensitivity to phenothiazines
The bottom line
Evidence rating strong. Most-documented uses: prevention and treatment of nausea and vomiting, motion sickness prevention, sedation (pre- and postoperative adjunct). 10 sources indexed (2003–2025), with 0 interaction records on file.
How it works, mechanistically.
Core mechanism
Blocks histamine H1 receptors (antihistaminic and antiemetic activity), dopamine receptors in the chemoreceptor trigger zone (antiemetic activity), and muscarinic cholinergic receptors (anticholinergic and anti-motion-sickness activity). The combination of these receptor antagonisms provides broad antiemetic and sedative effects.
Dosing & protocol.
Can be taken with or without food; take 30–60 minutes before travel for motion sickness
Full safety detail.
Side effects
- Pronounced sedation and drowsiness
- Dry mouth
- Blurred vision
- Urinary retention
- Constipation
- Dizziness
- Severe tissue injury with IV or subcutaneous injection
- Respiratory depression (especially in children)
Contraindications
- Children under 2 years of age (risk of fatal respiratory depression)
- Known hypersensitivity to phenothiazines
- Comatose states
- Concurrent use with other respiratory depressants in children
- Intra-arterial or subcutaneous injection (severe tissue necrosis)
- Lower respiratory tract symptoms including asthma
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Meta-analyses & systematic reviews
2- 1"Purple Drank" (Codeine and Promethazine Cough Syrup): A Systematic Review of a Social Phenomenon with Medical ImplicationsPMIDMiuli A, Stigliano G, Lalli A et al. · Journal of psychoactive drugs · 2020
Miuli A, Stigliano G, Lalli A et al.. "Purple Drank" (Codeine and Promethazine Cough Syrup): A Systematic Review of a Social Phenomenon with Medical Implications. Journal of psychoactive drugs. 2020
- 2[Haloperidol plus promethazine for agitated patients--a systematic review]PMIDHuf G, Coutinho ES, Adams CE · Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999) · 2009
Huf G, Coutinho ES, Adams CE. [Haloperidol plus promethazine for agitated patients--a systematic review]. Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999). 2009
Randomized controlled trials
3- 3Promethazine for nausea and vomiting prevention after gynaecological laparoscopic surgery: A randomized controlled trialPMIDRuijuan L, Jiqiang Z, Ruirui B et al. · Scientific reports · 2025
Ruijuan L, Jiqiang Z, Ruirui B et al.. Promethazine for nausea and vomiting prevention after gynaecological laparoscopic surgery: A randomized controlled trial. Scientific reports. 2025
- 4Promethazine Combined with Metoclopramide for the Prevention of Postoperative Nausea and Vomiting in Patients Undergoing Laparoscopic Colorectal Cancer Surgery: A Randomized Controlled TrialPMIDLiu R, Bi R, Zhang J et al. · Drug design, development and therapy · 2025
Liu R, Bi R, Zhang J et al.. Promethazine Combined with Metoclopramide for the Prevention of Postoperative Nausea and Vomiting in Patients Undergoing Laparoscopic Colorectal Cancer Surgery: A Randomized Controlled Trial. Drug design, development and therapy. 2025
- 5Promethazine plus sumatriptan in the treatment of migraine: a randomized clinical trialPMIDAsadollahi S, Heidari K, Vafaee R et al. · Headache · 2014
Asadollahi S, Heidari K, Vafaee R et al.. Promethazine plus sumatriptan in the treatment of migraine: a randomized clinical trial. Headache. 2014
Reviews & position papers
2- 6Promethazine: A Review of Therapeutic Uses and ToxicityPMIDLe CK, Stevens CA, Park JH et al. · The Journal of emergency medicine · 2025
Le CK, Stevens CA, Park JH et al.. Promethazine: A Review of Therapeutic Uses and Toxicity. The Journal of emergency medicine. 2025
- 7Interaction of carbamazepine and promethazine in rabbitsPMIDRukhadze MD, Alexishvili MM, Gonashvili MV et al. · Biomedical chromatography : BMC · 2003
Rukhadze MD, Alexishvili MM, Gonashvili MV et al.. Interaction of carbamazepine and promethazine in rabbits. Biomedical chromatography : BMC. 2003
Reference material
3- 8Gan TJ et al. Fourth Consensus Guidelines for the Management of Postoperative Nausea and Vomiting. Anesth Analg. 2020.Source linkedPMID
- 9Starke PR et al. FDA revision of promethazine labeling, changes and post-marketing safety events. J Clin Pharmacol. 2006.Source linkedPMID
- 10deSouza IS et al. Efficacy and Safety of Pharmacologic Therapies for Nausea and Emesis in the Emergency Department: A Systematic Review and Bayesian Network Meta-analysis. Ann Emerg Med. 2025.Source linkedPMID
Common questions.
Quick answers about Promethazine, drawn from the data on this page.
What is Promethazine?
A first-generation phenothiazine antihistamine with antiemetic, sedative, and anticholinergic properties. Promethazine is used for prevention and treatment of nausea and vomiting from various causes, motion sickness, allergic conditions, and as a pre- and postoperative sedative adjunct.
What is Promethazine used for?
Commonly cited benefits of Promethazine include: Prevention and treatment of nausea and vomiting; Motion sickness prevention; Sedation (pre- and postoperative adjunct); Allergic symptom relief. NutriStack rates the overall evidence as strong.
What is a typical dose of Promethazine?
A typical adult dose of Promethazine is 12.5–25 mg every 4–6 hours as needed (as prescribed by your physician). The commonly recommended form is Tablet, oral solution, rectal suppository, or IM injection. These are general ranges, not personalized advice; confirm the right dose with a clinician.
What are the side effects of Promethazine?
Reported side effects include pronounced sedation and drowsiness, dry mouth, blurred vision, urinary retention, constipation, dizziness. This is educational information; check with a healthcare professional before use.
How strong is the evidence for Promethazine?
NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.
Use this with your stack
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