Overview
Diphenhydramine - perhaps known most commonly as its brand name formulation Benadryl - is a first-generation H1 receptor antihistamine that is used extensively for the treatment of seasonal allergies, insect bites and stings, and rashes . However, it also has antiemetic, antitussive, hypnotic, and antiparkinson properties . As histamine receptors exist both peripherally and in the central nervous system, diphenhydramine has been shown to cause sedation due to its competitive antagonism of histamine H1 receptors within the central nervous system . While its use in allergy therapy can sometimes fall out of favor due to its sedative effect, diphenhydramine has been repurposed for use within many non-prescription over-the-counter sleep aids and cough-and-cold medications that have been marketed for "night time" use . Diphenhydramine is also used in combination with 8-chlorotheophylline as the anti-nausea drug Dimenhydrinate where it is utilized primarily for its antagonism of H1 histamine receptors within the vestibular system . Diphenhydramine has also been shown to be implicated in a number of neurotransmitter systems that affect behaviour including dopamine, norepinephrine, serotonin, acetylcholine, and opioid . As a result, diphenhydramine is being investigated for its anxiolytic and anti-depressant properties.
Indication
Diphenhydramine is a first-generation histamine H1 receptor antagonist (H1 antihistamine) that is widely available as a non-prescription, over-the-counter (OTC) medication. As an OTC medication, diphenhydramine is typically formulated as tablets and creams indicated for use in treating sneezing, runny nose, itchy/watery eyes, itching of nose or throat, insomnia, pruritis, urticaria, insect bites/stings, allergic rashes, and nausea . Additionally, when the use of oral diphenhydramine is impractical, there are also prescription-only formulations such as diphenhydramine injection products that are effective in adults and pediatric patients (other than premature infants and neonates) for: i) the amelioration of allergic reactions to blood or plasma, in anaphylaxis as an adjunct to epinephrine and other standard measures after acute allergic reaction symptoms have been controlled, and for other uncomplicated allergic conditions of the immediate type when oral therapy is impossible or contraindicated ; ii) the active treatment of motion sickness ; and iii) use in parkinsonism when oral therapy is impossible or contraindicated, as follows: parkinsonism in the elderly who are unable to tolerate more potent agents; mild cases of parkinsonism in other age groups, and in other cases of parkinsonism in combination with centrally acting anticholinergic agents .
Associated Conditions
- Allergic Reaction
- Allergic Rhinitis (AR)
- Allergic cough
- Allergy to Tree Pollen
- Anaphylaxis
- Angioedema
- Common Cold
- Conjunctival irritation
- Cough
- Cough Variant Asthma
- Cough caused by Common Cold
- Eye allergy
- Fever
- Insect Bites
- Insect Stings
- Insomnia
- Irritative cough
- Itching of the nose
- Itching of the throat
- Motion Sickness
- Nasal Congestion
- Oral Mucositis
- Pain
- Parkinsonian Syndromes
- Productive cough
- Pruritus
- Rash
- Rhinorrhoea
- Sinus Congestion
- Sinus headache
- Skin Irritation
- Sneezing
- Sunburn
- Symptoms of Acute Bronchitis Accompanied by Coughing
- Upper respiratory tract hypersensitivity reaction, site unspecified
- Urticaria
- Cold or flu syndrome
- Dermatographism
- Dry cough
- Watery itchy eyes
Clinical Trials
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Title | Posted | Study ID | Phase | Status | Sponsor |
|---|---|---|---|---|---|
2020/01/22 | Phase 3 | Completed | Ciusss de L'Est de l'Île de Montréal | ||
2020/01/13 | Phase 1 | Recruiting | |||
2020/01/09 | Phase 3 | Active, not recruiting | |||
2019/12/06 | Phase 2 | Completed | |||
2019/11/25 | Phase 3 | Completed | |||
2019/11/15 | Phase 2 | Completed | |||
2019/09/18 | Phase 1 | Completed | |||
2019/05/30 | Phase 4 | Completed | James A. Keeney | ||
2019/04/12 | Phase 2 | Recruiting | |||
2019/01/16 | Phase 1 | Active, not recruiting |
FDA Drug Approvals
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Approved Product | Manufacturer | NDC Code | Route | Strength | Effective Date |
|---|---|---|---|---|---|
| Micro Labs Limited | 42571-169 | INTRAMUSCULAR, INTRAVENOUS | 50 mg in 1 mL | 11/28/2022 | |
| WALGREEN COMPANY | 0363-6123 | ORAL | 50 mg in 1 1 | 5/27/2025 | |
| DOLGENCORP INC | 55910-450 | ORAL | 50 mg in 1 1 | 6/23/2025 | |
| Pharmaceutical Associates, Inc. | 0121-0978 | ORAL | 25 mg in 10 mL | 6/14/2022 | |
| Family Dollar (FAMILY WELLNESS) | 55319-562 | ORAL | 25 mg in 1 1 | 4/9/2025 | |
| BI-MART | 37835-519 | ORAL | 50 mg in 30 mL | 5/20/2025 | |
| Gland Pharma Limited | 68083-611 | INTRAMUSCULAR, INTRAVENOUS | 50 mg in 1 mL | 3/22/2024 | |
| Cardinal Health 107, LLC | 55154-9363 | INTRAVENOUS, INTRAMUSCULAR | 50 mg in 1 mL | 12/30/2019 | |
| WR Group, Inc. | 69607-0916 | ORAL | 50 mg in 1 1 | 3/24/2025 | |
| Walgreens | 0363-0844 | ORAL | 25 mg in 1 1 | 5/7/2025 |
EMA Drug Approvals
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Approved Product | Authorization Holder | Status | Issued Date |
|---|---|---|---|
| No EMA approvals found for this drug. | |||
HSA Drug Approvals
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Approved Product | Manufacturer | Approval Number | Dosage Form | Strength | Approval Date |
|---|---|---|---|---|---|
| No HSA approvals found for this drug. | |||||
NMPA Drug Approvals
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Approved Product | Company | Approval Number | Drug Type | Dosage Form | Approval Date |
|---|---|---|---|---|---|
| Diphenhydramine Hydrochloride Tablets | 国药准字H41023996 | 化学药品 | 片剂（糖衣） | 3/1/2023 | |
| Diphenhydramine Hydrochloride Tablets | 国药准字H32021430 | 化学药品 | 片剂 | 7/9/2020 | |
| Diphenhydramine Hydrochloride Tablets | 国药准字H12020157 | 化学药品 | 片剂 | 9/23/2020 | |
| Diphenhydramine Hydrochloride Tablets | 国药准字H44024124 | 化学药品 | 片剂 | 5/6/2020 | |
| Diphenhydramine Hydrochloride Tablets | 国药准字H20045353 | 化学药品 | 片剂 | 8/17/2020 | |
| Diphenhydramine Hydrochloride Tablets | 国药准字H42021571 | 化学药品 | 片剂(糖衣) | 6/10/2020 | |
| Diphenhydramine Hydrochloride Tablets | 国药准字H34021399 | 化学药品 | 片剂 | 8/7/2020 | |
| Diphenhydramine Hydrochloride Tablets | 国药准字H13020674 | 化学药品 | 片剂 | 1/15/2021 | |
| Diphenhydramine Hydrochloride Tablets | 国药准字H14021813 | 化学药品 | 片剂 | 8/13/2020 | |
| Diphenhydramine Hydrochloride Tablets | 国药准字H22023769 | 化学药品 | 片剂 | 12/31/2020 |
PPB Drug Approvals
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Approved Product | Registration No. | Company | Licence No. | Strength | Registration Date |
|---|---|---|---|---|---|
| ELLAWON CREAM | N/A | N/A | N/A | 1/14/1997 | |
| FULRANIL-T.G. CREAM | N/A | N/A | N/A | 8/31/1989 | |
| FOURDERM CREAM | N/A | N/A | N/A | 1/13/1989 | |
| PHYTOCINE CREAM | N/A | N/A | N/A | 1/24/1979 | |
| GENTAZOLE CREAM | N/A | N/A | N/A | 5/29/2011 | |
| KLOVATE CR | N/A | N/A | N/A | 8/23/1999 | |
| DERMAFULIN CREAM | N/A | N/A | N/A | 1/12/2009 | |
| DITASOL CREAM | N/A | N/A | N/A | 4/19/1999 | |
| ROCO CREAM | N/A | N/A | N/A | 12/2/2004 | |
| CHI-CREAM | N/A | N/A | N/A | 1/14/1997 |
TGA Drug Approvals
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Approved Product | ARTG ID | Sponsor | Registration Type | Status | Registration Date |
|---|---|---|---|---|---|
| No TGA approvals found for this drug. | |||||
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