Promethazine

Mechanism-of-action classes: Dopamine Antagonists; Histamine H1 Receptor Antagonists.

• Promethazine HCl Suppositories are useful for: Perennial and seasonal allergic rhinitis. Vasomotor rhinitis.ICD-10: J30.9

• Promethazine HCl Suppositories are contraindicated for use in pediatric patients less than two years of age. Promethazine HCl Suppositories are contraindicated in comatose states, and in individuals known to be hypersensitive or to have had an idiosyncratic reaction to promethazine or to other phenothiazines.contraindicated

Promethazine HCl Suppositories are contraindicated for children under 2 years of age (see WARNINGS - Black Box Warning and Use in Pediatric Patients ). Promethazine HCl Suppositories are for rectal administration only. Allergy - The average dose is 25 mg taken before retiring; however, 12.5 mg may be taken before meals and on retiring, if necessary. Single 25 mg doses at bedtime or 6.25 to 12.5 mg taken three times daily will usually suffice. After initiation of treatment in children or adults, dosage should be adjusted to the smallest amount adequate to relieve symptoms. The administration of promethazine hydrochloride in 25 mg doses will control minor transfusion reactions of an allergic nature. Motion Sickness - The average adult dose is 25 mg taken twice daily. The initial dose should be taken one-half to one hour before anticipated travel and be repeated 8 to 12 hours later, if necessary. On succeeding days of travel, it is recommended that 25 mg be given on arising and again before the evening meal. For children, Promethazine HCl Rectal Suppositories, 12.5 to 25 mg, twice daily, may be administered. Nausea and Vomiting - Antiemetics should not be used in vomiting of unknown etiology in children and adolescents (see WARNINGS - Use In Pediatric Patients ). The average effective dose of promethazine HCl 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.

PROMETHAZINE HCl SUPPOSITORIES SHOULD NOT BE USED IN PEDIATRIC PATIENTS LESS THAN 2 YEARS OF AGE BECAUSE OF THE POTENTIAL FOR FATAL RESPIRATORY DEPRESSION. POSTMARKETING CASES OF RESPIRATORY DEPRESSION, INCLUDING FATALITIES, HAVE BEEN REPORTED WITH USE OF PROMETHAZINE HCl SUPPOSITORIES IN PEDIATRIC PATIENTS LESS THAN 2 YEARS OF AGE. A WIDE RANGE OF WEIGHT-BASED DOSES OF PROMETHAZINE HCl SUPPOSITORIES HAVE RESULTED IN RESPIRATORY DEPRESSION IN THESE PATIENTS. CAUTION SHOULD BE EXERCISED WHEN ADMINISTERING PROMETHAZINE HCl TO PEDIATRIC PATIENTS 2 YEARS OF AGE AND OLDER. IT IS RECOMMENDED THAT THE LOWEST EFFECTIVE DOSE OF PROMETHAZINE HCl BE USED IN PEDIATRIC PATIENTS 2 YEARS OF AGE AND OLDER AND CONCOMITANT ADMINISTRATION OF OTHER DRUGS WITH RESPIRATORY DEPRESSANT EFFECTS BE AVOIDED. CNS Depression - Promethazine HCl Suppositories may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a vehicle or operating machinery. The impairment may be amplified by concomitant use of other central-nervous-system depressants such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore such agents should either be eliminated or given in reduced dosage in the presence of promethazine HCl (see PRECAUTIONS - Information for Patients and Drug Interactions ). Respiratory Depression - Promethazine HCl Suppositories may lead to potentially fatal respiratory depression.

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 and 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 - Respiratory Depression ). Other - Angioneurotic edema. Neuroleptic malignant syndrome (potentially fatal) has also been reported. (See WARNINGS – Neuroleptic Malignant Syndrome ). Paradoxical Reactions - Hyperexcitability and abnormal movements have been reported in patients following a single administration of promethazine HCl. Consideration should be given to the discontinuation of promethazine HCl 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.

Pregnancy: Teratogenic Effects: Teratogenic effects have not been demonstrated in rat-feeding studies at doses of 6.25 and 12.5 mg/kg of promethazine. These doses are from approximately 2.1 to 4.2 times the maximum recommended total daily dose of promethazine for a 50-kg subject, depending upon the indication for which the drug is prescribed. Daily doses of 25 mg/kg intraperitoneally have been found to produce fetal mortality in rats. Specific studies to test the action of the drug on parturition, lactation, and development of the animal neonate were not done, but a general preliminary study in rats indicated no effect on these parameters. Although antihistamines have been found to produce fetal mortality in rodents, the pharmacological effects of histamine in the rodent do not parallel those in man. There are no adequate and well-controlled studies of Promethazine HCl Suppositories in pregnant women. Promethazine HCl Suppositories should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Nonteratogenic Effects - Promethazine HCl Suppositories administered to a pregnant woman within two weeks of delivery may inhibit platelet aggregation in the newborn.

Signs and symptoms of overdosage with promethazine HCl range from mild depression of the central nervous system and cardiovascular system to profound hypotension, respiratory depression, unconsciousness, and sudden death. Other reported reactions include hyperreflexia, hypertonia, ataxia, athetosis, and extensor-plantar reflexes (Babinski reflex). Stimulation may be evident, especially in children and geriatric patients. Convulsions may rarely occur. A paradoxical-type reaction has been reported in children receiving single doses of 75 mg to 125 mg orally, characterized by hyperexcitability and nightmares. Atropine-like signs and symptoms-dry mouth, fixed, dilated pupils, flushing, as well as gastrointestinal symptoms, may occur. Treatment - Treatment of overdosage is essentially symptomatic and supportive. Only in cases of extreme overdosage or individual sensitivity do vital signs, including respiration, pulse, blood pressure, temperature, and EKG, need to be monitored. Activated charcoal orally or by lavage may be given, or sodium or magnesium sulfate orally as a cathartic.

• Dec 3, 1957NDANDA011265Ani Pharms
• Sep 19, 1973ANDAANDA083312Hikma
• Sep 19, 1973ANDAANDA083426Watson Labs
• Sep 21, 1973ANDAANDA083711Watson Labs
• Nov 15, 1982ANDAANDA087953Pharmobedient
• Jan 4, 1985ANDAANDA088864Pharmobedient
• Aug 14, 1987ANDAANDA087165Cosette
• Sep 25, 1998ANDAANDA040026Chartwell Rx

1. 1Dependence3,58616%
2. 2Nausea2,61312%
3. 3Vomiting1,7828.0%
4. 4Pain1,6847.5%
5. 5Fatigue1,4806.6%
6. 6Diarrhoea1,3265.9%
7. 7Headache1,2745.7%
8. 8Dyspnoea1,1295.0%
9. 9Back Pain1,0044.5%
10. 10Anxiety9454.2%
11. 11Drug Ineffective8944.0%
12. 12Overdose8874.0%
13. 13Pneumonia8363.7%
14. 14Asthenia8293.7%
15. 15Arthralgia8223.7%

Recent PubMed references pinned to Promethazine as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• A paper-based sensor with distance readout for rapid on-site screening of promethazine hydrochloride in beverages.
  Analytica chimica acta · 2026 · Xu J, Zhang X, Lin S, et al.
  PMID 42108063DOI 10.1016/j.aca.2026.345537
• Promethazine provokes behavioral alterations and disrupts redox homeostasis in planarians.
  Neurotoxicology · 2026 · Mayeski KK, Solek CC, Carus KM, et al.
  PMID 41698614DOI 10.1016/j.neuro.2026.103408
• Effect of promethazine and hydroxyzine, two inhibitors of Tumor Controlled Translational Protein (TCTP), on the growth of in vitro culture of Trypanosoma brucei gambiense and Trypanosoma congolense.
  Experimental parasitology · 2026 · Bossard G, Geiger A
  PMID 41679619DOI 10.1016/j.exppara.2025.109087
• [Clinical characteristics of cyclic vomiting syndrome and the therapeutic efficacy of chlorpromazine combined with promethazine].
  Zhonghua er ke za zhi = Chinese journal of pediatrics · 2026 · Xiong LY, Chen PY, Xie J, et al.
  PMID 41674423DOI 10.3760/cma.j.cn112140-20250601-00467
• Efficacy and safety of haloperidol-promethazine combination versus chlorpromazine-promethazine in managing acute behavioral disturbances and violent behavior in psychiatric patients.
  Psychiatry research · 2026 · Huang J, Zhang PH, Li WF, et al.
  PMID 41420909DOI 10.1016/j.psychres.2025.116908
• Preventive activity of promethazine against fluconazole-resistant Candida spp. biofilms fixed on urinary catheters.
  Biofouling · 2026 · Rocha da Silva C, Andrade Neto JB, Pessoa de Farias Cabral V, et al.
  PMID 41417270DOI 10.1080/08927014.2025.2605127
• Promethazine Effects on Motion Sickness During Altered Gravity Induced by Parabolic Flight.
  Aerospace medicine and human performance · 2025 · Abbott R, Weinrich MM, Keller NW, et al.
  PMID 41253367DOI 10.3357/AMHP.6669.2025
• Development and validation of a green UV-Vis spectrophotometric method for the determination of potassium bromate in bread using promethazine.
  Food chemistry · 2025 · Alshutairi AM, Althaqfi FM, Alansari MA, et al.
  PMID 41092591DOI 10.1016/j.foodchem.2025.146577

The 10 most recently updated of 1,239 ClinicalTrials.gov registrations naming Promethazine as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• A Clinical Study of Gocatamig (MK-6070) and Infinatamab Deruxtecan (MK-2400) in People With Small Cell Lung Cancer (MK-6070-003)
  Recruiting · Phase 1 · Phase 2 · Interventional · 170 enrolled · Merck Sharp & Dohme LLC
  NCT07227597updated 2026-06-12
• Losartan for Diffuse Myocardial Fibrosis in Sickle Cell Disease
  Completed · Phase 2 · Interventional · 14 enrolled · Children's Hospital Medical Center, Cincinnati
  NCT05012631updated 2026-06-12
• Sacituzumab Tirumotecan (MK-2870) in Combination With Pembrolizumab Versus Pembrolizumab Alone in Metastatic Non-small Cell Lung Cancer (NSCLC) With Programmed Cell Death Ligand 1 (PD-L1) Tumor Proportion Score (TPS) ≥ 50% (MK-2870-007)
  Recruiting · Phase 3 · Interventional · 614 enrolled · Merck Sharp & Dohme LLC
  NCT06170788updated 2026-06-12
• Toripalimab Combined With Platinum-based Chemotherapy With or Without H1 Receptor Antagonist in the Perioperative Treatment of Resectable Non-small Cell Lung Cancer
  Not yet recruiting · Phase 2 · Interventional · 120 enrolled · Tianjin Medical University Cancer Institute and Hospital
  NCT07358689updated 2026-06-12
• Losartan + Sunitinib in Treatment of Osteosarcoma
  Recruiting · Phase 1 · Interventional · 41 enrolled · University of Colorado, Denver
  NCT03900793updated 2026-06-11
• Siplizumab for Sickle Cell Disease Transplant
  Terminated · Phase 1 · Phase 2 · Interventional · 1 enrolled · Columbia University
  NCT06078696updated 2026-06-10
• Conventional Prophylactic Oral Dexamethasone vs Short-course IV Dexamethasone in Paclitaxel Hypersensitivity
  Completed · Phase 3 · Interventional · 90 enrolled · Loma Linda University
  NCT03598426updated 2026-06-09
• Comparing Digital Therapy, Trazodone, and Daridorexant for Menopause-Related Insomnia Symptoms
  Recruiting · Phase 4 · Interventional · 1,000 enrolled · Brigham and Women's Hospital
  NCT07136415updated 2026-06-08
• A SMART Approach to Evaluating the Benefits of Common Prescription and OTC Medications for Insomnia
  Recruiting · Phase 4 · Interventional · 1,200 enrolled · University of Pennsylvania
  NCT07542756updated 2026-06-05
• A Clinical Trial of MK-1045 in People With B-cell Acute Lymphoblastic Leukemia (MK-1045-005)
  Recruiting · Phase 2 · Phase 3 · Interventional · 340 enrolled · Merck Sharp & Dohme LLC
  NCT07570173updated 2026-06-05

Frequently asked questions

How does Promethazine work?

Mechanism-of-action classes: Dopamine Antagonists; Histamine H1 Receptor Antagonists.

What is Promethazine used for?

According to FDA labeling, Promethazine carries indications including: Promethazine HCl Suppositories are useful for: Perennial and seasonal allergic rhinitis. Vasomotor rhinitis.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Promethazine?

Promethazine is classified as Antihistamines for topical use, Phenothiazine derivatives, Phenothiazine, Dopamine Antagonists, Histamine H1 Receptor Antagonists, Decreased Central Nervous System Organized Electrical Activity, Decreased Disorganized Electrical Activity, Decreased Dopamine Activity, Decreased Histamine Activity, Decreased Norepinephrine Activity, Emesis Suppression.

What are the brand names for Promethazine?

Promethazine is marketed under brand names including Phenadoz, Phenergan, Promethegan.

What are the contraindications for Promethazine?

Promethazine labeling lists contraindications including: Promethazine HCl Suppositories are contraindicated for use in pediatric patients less than two years of age. Promethazine HCl Suppositories are contraindicated in comatose states, and in individuals known to be hypersensitive or to have had an idiosyncratic reaction to promethazine or to other phenothiazines.. Always consult the full prescribing information and a clinician.