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Diphenhydramine HCL
Diphenhydramine blocks histamine H1 receptors, preventing histamine-mediated allergic and inflammatory responses.
Diphenhydramine blocks histamine H1 receptors, preventing histamine-mediated allergic and inflammatory responses. Used for Allergic reactions and urticaria, Pruritus, Allergic rhinitis.
At a glance
| Generic name | Diphenhydramine HCL |
|---|---|
| Also known as | Diphenhydramine Hydrochloride, Benadryl, Unisom, ZzzQuil, Children's Benadryl Allergy Liquid |
| Sponsor | National Cancer Institute (NCI) |
| Drug class | First-generation H1 receptor antagonist (antihistamine) |
| Target | Histamine H1 receptor |
| Modality | Small molecule |
| Therapeutic area | Allergy/Immunology |
| Phase | FDA-approved |
Mechanism of action
Diphenhydramine is a first-generation antihistamine that competitively antagonizes H1 histamine receptors on various tissues. By blocking histamine binding, it reduces allergic symptoms such as itching, urticaria, and angioedema, and also produces sedation due to central nervous system penetration. It has additional anticholinergic properties that contribute to its antiemetic and anti-motion sickness effects.
Approved indications
- Allergic reactions and urticaria
- Pruritus
- Allergic rhinitis
- Motion sickness and nausea
- Insomnia
Common side effects
- Drowsiness/sedation
- Dizziness
- Dry mouth
- Headache
- Anticholinergic effects (urinary retention, constipation)
Key clinical trials
- Trial of Diphenhydramine for Sleep in Children With Autism (PHASE2)
- Trial of Zolpidem for Sleep in Children With Autism (PHASE2)
- 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) (PHASE3)
- A Study of Daratumumab, Carfilzomib, Lenalidomide, and Dexamethasone in Patients With Newly-Diagnosed Multiple Myeloma (PHASE2)
- A Clinical Study of Gocatamig (MK-6070) and Infinatamab Deruxtecan (MK-2400) in People With Small Cell Lung Cancer (MK-6070-003) (PHASE1, PHASE2)
- Cetuximab After Immunotherapy for the Treatment of Head and Neck Squamous Cell Cancer (PHASE2)
- Durvalumab and Vicineum in Subjects With High-Grade Non-Muscle-Invasive Bladder Cancer Previously Treated With Bacillus Calmette-Guerin (BCG) (PHASE1)
- IMPOWER-QoL: IMPact Of Discontinuing Premedication for WEekly Paclitaxel on bReast Cancer Patient's Quality Of Life (NA)
Primary sources
Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.
| Source | Used for |
|---|---|
| ClinicalTrials.gov | Trial enrolment, design, endpoints, results |
Competitive intelligence
For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:
- Diphenhydramine HCL CI brief — competitive landscape report
- Diphenhydramine HCL updates RSS · CI watch RSS
- National Cancer Institute (NCI) portfolio CI