Promethazine

96 interactions 6 explained in plain English

Also sold as: Phenadoz Phenergan Promethegan

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated Jul 4, 2026 · Editorial policy · Data sources

Sources: FDA prescribing information (Structured Product Labeling), the published literature cited in each entry, DDInter 2.0 (a major open-access drug-interaction database), and legacy DrugBank interaction data distributed by the NIH's RxNav service (decommissioned in 2024) — analyzed and reviewed by our pharmacist team. How we build this library →

Most serious with: Butorphanol Nasal Spray Amitriptyline Alfuzosin Felbamate Butorphanol Injection Diphenhydramine Topical

94 Major 2 Moderate

All (96) Major (94) Moderate (2)

Major

Promethazine Felbamate Felbatol An increased risk of QT interval prolongation Details Promethazine Fentanyl Transdermal Patch Duragesic® Increased risk of paralytic ileus and an increased risk of respiratory and CNS depression Details Promethazine Flecainide Tambocor® An increased risk of QT interval prolongation Details Promethazine Foscarnet Injection Foscavir Increased risk of QT interval prolongation Details Promethazine Fostemsavir Rukobia Increased risk of torsade de pointes Details Promethazine Galantamine Razadyne An increased risk of QT interval prolongation Details Promethazine Gemifloxacin Factive An increased risk of QT interval prolongation Details Promethazine Glasdegib Daurismo Increased risk of QT interval prolongation Details Promethazine Glucagon Injection Baqsimi Increased risk of gastrointestinal side effects Details Promethazine Glucagon Injection / Solution Baqsimi Increased risk of gastrointestinal side effects Details Promethazine Glucagon Nasal Powder Baqsimi Increased risk of gastrointestinal side effects Details Promethazine Glycopyrronium Topical Cuvposa® An increased risk of anticholinergic side effects Details Promethazine Goserelin Implant Zoladex Increased risk of QT interval prolongation Details Promethazine Granisetron Transdermal Patch Sancuso An increased risk of QT interval prolongation Details Promethazine Granisetron Injection Granisol An increased risk of QT interval prolongation Details Promethazine Histrelin Implant Supprelin Increased risk of QT interval prolongation Details Promethazine Hydromorphone Injection Dilaudid Increased risk of paralytic ileus and an increased risk of respiratory and CNS depression Details Promethazine Hydromorphone Rectal available generically Increased risk of paralytic ileus and an increased risk of respiratory and CNS depression Details Promethazine Hydroxychloroquine Plaquenil An increased risk of seizures and an increased risk of QT interval prolongation Details Promethazine Inotuzumab Ozogamicin Injection Besponsa Increased risk of QT interval prolongation Details Promethazine Ipratropium Nasal Spray Atrovent Nasal Spray® Increased risk of urinary retention and/or severe constipation leading to paralytic ileus Details Promethazine Ipratropium Oral Inhalation Atrovent® HFA Increased risk of urinary retention and/or severe constipation leading to paralytic ileus Details Promethazine Isradipine DynaCirc® An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest) Details Promethazine Ivabradine Corlanor Increased risk of QT prolongation Details Promethazine Ketoconazole Topical Extina® Foam Increased risk of QT interval prolongation Details Promethazine Lacosamide Injection Motpoly An increased risk of CNS depression Details Promethazine Lefamulin Xenleta Increased risk of QT interval prolongation Details Promethazine Lenvatinib Lenvima Increased risk of QT-interval prolongation Details Promethazine Levodopa Oral Inhalation Inbrija Reduce efficacy of levodopa (foslevodopa), an increased risk of exacerbating psychosis [or symptoms of Parkinson's disease: delusi... Details Promethazine Levofloxacin Levaquin Increased risk of QT interval prolongation Details Promethazine Levofloxacin Injection Levaquin Increased risk of QT interval prolongation Details Promethazine Lithium Carbonate Lithobid Weakness, dyskinesias, increased extrapyramidal symptoms, encephalopathy, and brain damage Details Promethazine Loperamide Diamode An increased risk of QT interval prolongation, which may increase risk of cardiotoxicity (torsade de pointes, cardiac arrest) Details Promethazine Mefloquine Lariam® An increased risk of QT interval prolongation Details Promethazine Metoclopramide Injection Gimoti Increased risk of CNS depression Details Promethazine Metoclopramide Nasal Spray Gimoti Increased risk of CNS depression Details Promethazine Metronidazole Flagyl An increased risk of QT interval prolongation Details Promethazine Metronidazole Injection Flagyl An increased risk of QT interval prolongation Details Promethazine Metronidazole Topical MetroCream® An increased risk of QT interval prolongation Details Promethazine Metronidazole Vaginal MetroGel® Vaginal An increased risk of QT interval prolongation Details

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Educational information only, not medical advice. Always confirm interactions with your pharmacist or prescriber before making any change to your medications.