Diphenhydramine
GET
/api/v1/drug/diphenhydramine2D structure
2-benzhydryloxy-N,N-dimethylethanamine
SMILES CN(C)CCOC(C1=CC=CC=C1)C2=CC=CC=C2
InChIKey ZZVUWRFHKOJYTH-UHFFFAOYSA-N
Mechanism of action
Sourced from openFDAMechanism-of-action class: Histamine H1 Receptor Antagonists.
Histamine H1 Receptor
Indications
Sourced from openFDA- Uses temporarily relieves these symptoms due to hay fever or other respiratory allergies: ■ sneezing ■ itching of the nose or throat ■ runny nose ■ itchy watery eyes ■temporarily relieves these symptoms due to the common cold: ■ sneezing ■ runny noseICD-10: J00
Dosage & administration
Sourced from openFDADirections ■ if needed, take every 4-6 hours ■ do not take more than 6 doses in 24-hours children under 4 years of age Do not use children 4 to under 6 years of age Do not use unless directed by a doctor children 6 to under 12 years of age 1 to 2 teaspoonfuls (5 ml to 10 ml)
Warnings & precautions
Sourced from openFDADo not use ■ with any other product containing diphenhydramine, even one used on skin ■ to make a child sleepy Ask a doctor before use if the child has ■ glaucoma ■ a breathing problem such as chronic bronchitis
Approval history
Sourced from openFDA- Nov 27, 1972ANDAANDA080817West-ward Pharms Int
- Feb 10, 1982ANDAANDA087513Pharm Assoc
- May 28, 2002ANDAANDA040466App Pharms
- Dec 21, 2005NDANDA021393Haleon Us Holdings
- Dec 21, 2005NDANDA021394Haleon Us Holdings
- Dec 22, 2008ANDAANDA079113Perrigo R And D
- Jul 8, 2009ANDAANDA090619Dr Reddys Labs Ltd
- Jan 17, 2014NDANDA205352Bayer Hlthcare
FAERS reports
Reference statistics only. FAERS reports are voluntarily submitted and are not incidence rates, safety signals, or causal evidence. Counts reflect reporting volume — how often a reaction was reported, not how often it occurs. For decision-grade use, consult openFDA and the FAERS Public Dashboard directly.
195,245 total reports matchedLatest report Share = reports listing the reaction ÷ total matched reports. Rows can sum to >100% because a single report often lists multiple reactions.
- 1Off Label Use18,8659.7%
- 2Fatigue17,7229.1%
- 3Nausea16,2668.3%
- 4Headache15,5478.0%
- 5Drug Ineffective14,9277.6%
- 6Pain13,8887.1%
- 7Dyspnoea12,0426.2%
- 8Pruritus10,8235.5%
- 9Arthralgia10,1615.2%
- 10Diarrhoea9,9895.1%
- 11Infusion Related Reaction9,9615.1%
- 12Rash9,8575.0%
- 13Vomiting9,2594.7%
- 14Pyrexia9,1314.7%
- 15Dizziness9,1204.7%
Literature
Recent PubMed references pinned to Diphenhydramine as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.
- From over-the-counter to criminal evidence: Pharmacological profiles, analytical methods, and forensic insights into diphenhydramine's role in drug-facilitated crime.Journal of forensic and legal medicine · 2026 · Kashindye RC, Yadav D, Yadav R, et al.PMID 41633170DOI 10.1016/j.jflm.2026.103085
- Caffeine potentiates the dependence induced by central nervous system depressants contained in over-the-counter medications in mice.The Journal of toxicological sciences · 2026 · Yonemura-Hirata A, Kaizaki-Mitsumoto A, Numazawa S, et al.PMID 41621858DOI 10.2131/jts.51.131
- Lidocaine for diphenhydramine-induced ventricular tachycardia: A case report.The American journal of emergency medicine · 2026 · Carroll S, McGee M, Audette M, et al.PMID 41610479DOI 10.1016/j.ajem.2026.01.040
- Multisystem Sequelae of Chronic Diphenhydramine Misuse in an Adolescent: A Case Highlighting the Importance of Comprehensive History-Taking.Psychopharmacology bulletin · 2026 · Howe JM, Vora J, Reddy A, et al.PMID 41532003DOI 10.64719/pb.15435
- False-positive tricyclic antidepressant results in diphenhydramine overdose: a report of two cases and a literature review.BMC neurology · 2026 · Ito R, Kobayashi S, Terashima H, et al.PMID 41514262DOI 10.1186/s12883-025-04620-8
- Death due to diphenhydramine toxicity: A 9-year review from the Cook County Medical Examiner's Office and a review of the literature.Journal of forensic sciences · 2026 · Macorano E, Tarozzi I, Gitto L, et al.PMID 41310982DOI 10.1111/1556-4029.70239
- Diphenhydramine, Sodium Bicarbonate, or Combination for Acute Peripheral Vertigo: A Randomized Clinical Trial.JAMA network open · 2025 · Chi CY, Chen YC, Cheng MT, et al.PMID 41196596DOI 10.1001/jamanetworkopen.2025.41472
- Development and characterisation of fast dispersible dimenhydrinate tablets: Compactional study and in-silico PBPK modeling.PloS one · 2025 · Maqbool U, Zafar F, Yasmin R, et al.PMID 41144537DOI 10.1371/journal.pone.0334421
Clinical trials
The 10 most recently updated of 1,239 ClinicalTrials.gov registrations naming Diphenhydramine 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 LLCNCT07227597updated 2026-06-12
- Losartan for Diffuse Myocardial Fibrosis in Sickle Cell DiseaseCompleted · Phase 2 · Interventional · 14 enrolled · Children's Hospital Medical Center, CincinnatiNCT05012631updated 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 LLCNCT06170788updated 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 CancerNot yet recruiting · Phase 2 · Interventional · 120 enrolled · Tianjin Medical University Cancer Institute and HospitalNCT07358689updated 2026-06-12
- Losartan + Sunitinib in Treatment of OsteosarcomaRecruiting · Phase 1 · Interventional · 41 enrolled · University of Colorado, DenverNCT03900793updated 2026-06-11
- Siplizumab for Sickle Cell Disease TransplantTerminated · Phase 1 · Phase 2 · Interventional · 1 enrolled · Columbia UniversityNCT06078696updated 2026-06-10
- Conventional Prophylactic Oral Dexamethasone vs Short-course IV Dexamethasone in Paclitaxel HypersensitivityCompleted · Phase 3 · Interventional · 90 enrolled · Loma Linda UniversityNCT03598426updated 2026-06-09
- Comparing Digital Therapy, Trazodone, and Daridorexant for Menopause-Related Insomnia SymptomsRecruiting · Phase 4 · Interventional · 1,000 enrolled · Brigham and Women's HospitalNCT07136415updated 2026-06-08
- A SMART Approach to Evaluating the Benefits of Common Prescription and OTC Medications for InsomniaRecruiting · Phase 4 · Interventional · 1,200 enrolled · University of PennsylvaniaNCT07542756updated 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 LLCNCT07570173updated 2026-06-05
Structural analogs
Ranked by 2D fingerprint (Tanimoto) similarity over PubChem structures. Structural proximity only — not a claim of therapeutic equivalence.
Frequently asked questions
- How does Diphenhydramine work?
- Mechanism-of-action class: Histamine H1 Receptor Antagonists.
- What is Diphenhydramine used for?
- According to FDA labeling, Diphenhydramine carries indications including: Uses temporarily relieves these symptoms due to hay fever or other respiratory allergies: ■ sneezing ■ itching of the nose or throat ■ runny nose ■ itchy watery eyes ■temporarily relieves these symptoms due to the common cold: ■ sneezing ■ runny nose. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.
- What class of drug is Diphenhydramine?
- Diphenhydramine is classified as Aminoalkyl ethers, Antihistamines for topical use, Histamine-1 Receptor Antagonist, Histamine H1 Receptor Antagonists.
- What are the brand names for Diphenhydramine?
- Diphenhydramine is marketed under brand names including Acetadryl, Aleve PM, Banophen, Banophen Cream, Benadryl, Benadryl Allergy Plus Congestion, Benadryl Itch Stopping, Benadryl-D Allergy and Sinus.
Note. Data for
diphenhydramine is illustrative MVP content compiled from public sources. pharmacopeia is for educational and informational use only and is not a substitute for professional medical advice.