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Last Updated: April 3, 2026

CLINICAL TRIALS PROFILE FOR DIPHENHYDRAMINE HYDROCHLORIDE


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505(b)(2) Clinical Trials for diphenhydramine hydrochloride

This table shows clinical trials for potential 505(b)(2) applications. See the next table for all clinical trials
Trial Type Trial ID Title Status Sponsor Phase Start Date Summary
OTC NCT01365052 ↗ Safety Trial of Naproxen Sodium/ Diphenhydramine Completed Bayer Phase 3 2011-05-01 The purpose of this trial is to see how safe the combination of naproxen sodium 440 mg and diphenhydramine hydrochloride (DPH) 50 mg (the investigational product) is compared to placebo (capsules containing no drug) when taken for 10 days.
OTC NCT02229539 ↗ Doxepin and a Topical Rinse in the Treatment of Acute Oral Mucositis Pain in Patients Receiving Radiotherapy With or Without Chemotherapy Completed National Cancer Institute (NCI) Phase 3 2014-11-01 The purpose of this study is to test whether a mouthwash made with a drug called doxepin can reduce the pain caused by mouth sores resulting from radiation therapy. A number of mouth rinse preparations exist for patients with treatment-related oral mucositis pain such as the DLA rinse, an over-the-counter medication. This study will evaluate the effects of doxepin compared to DLA (diphenhydramine, lidocaine and antacids) and placebo.Doxepin is approved by the Food and Drug Administration (FDA) for the treatment of depression, anxiety, long-term pain management, as well as management of rash.
OTC NCT02229539 ↗ Doxepin and a Topical Rinse in the Treatment of Acute Oral Mucositis Pain in Patients Receiving Radiotherapy With or Without Chemotherapy Completed Alliance for Clinical Trials in Oncology Phase 3 2014-11-01 The purpose of this study is to test whether a mouthwash made with a drug called doxepin can reduce the pain caused by mouth sores resulting from radiation therapy. A number of mouth rinse preparations exist for patients with treatment-related oral mucositis pain such as the DLA rinse, an over-the-counter medication. This study will evaluate the effects of doxepin compared to DLA (diphenhydramine, lidocaine and antacids) and placebo.Doxepin is approved by the Food and Drug Administration (FDA) for the treatment of depression, anxiety, long-term pain management, as well as management of rash.
OTC NCT02474199 ↗ Donor Alloantigen Reactive Tregs (darTregs) for Calcineurin Inhibitor (CNI) Reduction Completed Clinical Trials in Organ Transplantation in Children Phase 1/Phase 2 2016-06-06 This research study is for liver transplant recipients and their respective living donors. The purpose of this study is: 1. To see if it is safe for liver recipients to receive one dose of donor reactive T regulatory cells (Tregs) 2. To see if the Tregs allows a liver recipient to take less, or completely stop medications normally taken after receiving an organ transplant.
OTC NCT02474199 ↗ Donor Alloantigen Reactive Tregs (darTregs) for Calcineurin Inhibitor (CNI) Reduction Completed Rho Federal Systems Division, Inc. Phase 1/Phase 2 2016-06-06 This research study is for liver transplant recipients and their respective living donors. The purpose of this study is: 1. To see if it is safe for liver recipients to receive one dose of donor reactive T regulatory cells (Tregs) 2. To see if the Tregs allows a liver recipient to take less, or completely stop medications normally taken after receiving an organ transplant.
>Trial Type >Trial ID >Title >Status >Phase >Start Date >Summary

All Clinical Trials for diphenhydramine hydrochloride

Trial ID Title Status Sponsor Phase Start Date Summary
NCT00011804 ↗ Topiramate in the Treatment of Sciatica Completed National Institute of Dental and Craniofacial Research (NIDCR) Phase 2 2001-02-01 This study will test the effectiveness of topiramate to treat pain caused by lumbar radiculopathy, or sciatica. Sciatica results from damage to the lumbar nerve roots, typically causing back pain and sharp, shooting pain down one or both legs. Although sciatica is common, there are no good treatments for it. Topiramate belongs to a group of medications commonly used to treat pain caused by nerve damage. Patients between 18 and 75 years of age who have had sciatica pain daily for at least 3 months may be eligible for this study. (This is taken from the first paragraph of the Qualification Criteria in the consent form. The inclusion criteria on page 6 of the protocol say "low back pain of 3 months duration or longer present at least 5 out of 7 days a week" and signs and symptoms of lumbar radiculopathy. Which is correct?) Participants will provide a medical history, as well as occupational and social information. They will undergo a standard neurological examination, including a test of cognitive (thinking) abilities, muscular function, reflexes and a sensory examination. The latter involves testing with a pin placed on the surface of the skin. Participants will also have routine blood tests and will fill out questionnaires on their daily functioning and psychological well being. Additional procedures may include magnetic resonance imaging (MRI) scans and possible referral to a psychiatrist for evaluation of depression or emotional difficulties. This "cross-over" study consists of two parts. In one part, patients will receive topiramate and in the other, an active placebo. An active placebo is a drug that does not work for the problem being studied but whose side effects are like those of the test drug. Diphenhydramine (Benadryl) is the active placebo used in this study. Diphenhydramine is an allergy medication with very mild side effects, such as drowsiness. During both parts of the study-topiramate and placebo-patients will keep a daily log in which they rate their pain, record other procedures they undergo, such as injections and manipulations, and record medication side effects. In the first week of the study, patients will remain on their current medications and record pain levels once a day. After the first week, they will begin taking the study drugs-either topiramate in increasing doses ranging from 50 to 400 mg. or diphenhydramine in doses ranging from 6.25 to 50 mg. The drug doses will be increased gradually over 4 weeks to minimize possible side effects. Increases will continue until the maximum tolerated dose is reached. Patients will continue on the highest tolerated dose for two weeks and then be tapered off gradually over 12 days. They will remain off drugs completely for a 2-day washout period and then begin the next treatment. Those who took topiramate for the first part will take diphenhydramine for the second part and vice versa. A study nurse will call patients twice a week throughout the study to check for problems and answer questions. A physician will see patients 6 weeks after the start of each treatment. During the last visit, at the end of the study, patients will repeat the questionnaires they filled out at the beginning of the study. Patients and their doctors will be informed of the medications that were effective in each individual's care.
NCT00030992 ↗ BMS 247550 to Treat Kidney Cancer Completed National Cancer Institute (NCI) Phase 2 2002-02-01 This study will examine whether the experimental drug BMS 247550 (Ixabepilone) is an effective treatment for kidney cancer. BMS 247550 belongs to a class of drugs called epothilones that interfere with the ability of cancer cells to divide. In the way they kill cells, they are very similar to a class of compounds known as the taxanes, which include the drug Taxol. Other characteristics of the epothilones, however, enable them to work in cells that are resistant to Taxol. Patients 18 years of age or older with kidney cancer that has not spread to the central nervous system (unless the brain tumor has remained stable for at least six months after surgical or radiation treatment) may be eligible for this study. Pregnant or nursing women may not participate. Candidates are screened with various tests that may include blood and urine tests, electrocardiogram (EKG), and chest x-ray. Computerized tomography (CT) scans or X-rays, and possibly nuclear medicine studies may be done to determine the extent of disease. Participants receive BMS 247550 by a 1-hour infusion into a vein for 5 consecutive days (days 1, 2, 3, 4 and 5) of each 21-day treatment cycle. Patients must stay in the National Institutes of Health (NIH) area near Bethesda, Maryland, for 7 to 8 days during the first treatment cycle and for the 5 days of treatment in subsequent cycles. The total number of cycles will vary among patients, depending on their individual clinical situation. The drug dose may be increased gradually in subsequent cycles in patients who can tolerate such increases. In addition, participants undergo the following tests and procedures: - Periodic physical examinations and frequent blood tests - X-ray and other imaging studies to determine if the tumor is responding to the treatment. - Tumor biopsies to confirm the diagnosis or spread of tumor and to examine the reaction of certain proteins in cancer cells to BMS 247550. Two biopsies will be done. For this procedure, a small piece of tumor tissue is withdrawn through a needle under local anesthetic. Treatment will be stopped in patients whose tumor grows while receiving BMS 247550. Patients whose tumor disappears completely will be followed at NIH periodically for examinations and tests. Patients whose disease does not completely resolve or whose disease recurs may be advised of other appropriate research protocols at NIH or, if none are available, will be returned to the care of their local doctor.
NCT00038402 ↗ Evaluation of the Addition of Herceptin to Standard Chemotherapy in the Neoadjuvant Setting for Operable Breast Cancer Completed Genentech, Inc. Phase 3 2001-04-01 The purpose of this study is to evaluate the addition of Herceptin to standard chemotherapy treatment of patients newly diagnosed with operable breast cancer. Other objectives: 1) to evaluate the potential of this therapy to reduce the size of the tumor and increase the possibility of breast conservative surgery, 2) evaluate the ability of this regimen to prevent recurrence of breast cancer and impact on survival, 3) determine side effect profile with the addition of Herceptin, and 4) evaluate significance of HER2 expression by two different methods.
NCT00038402 ↗ Evaluation of the Addition of Herceptin to Standard Chemotherapy in the Neoadjuvant Setting for Operable Breast Cancer Completed M.D. Anderson Cancer Center Phase 3 2001-04-01 The purpose of this study is to evaluate the addition of Herceptin to standard chemotherapy treatment of patients newly diagnosed with operable breast cancer. Other objectives: 1) to evaluate the potential of this therapy to reduce the size of the tumor and increase the possibility of breast conservative surgery, 2) evaluate the ability of this regimen to prevent recurrence of breast cancer and impact on survival, 3) determine side effect profile with the addition of Herceptin, and 4) evaluate significance of HER2 expression by two different methods.
NCT00038623 ↗ Study Of Yttrium-ibritumomab (Zevalin) For the Treatment Of Patients With Relapsed And Refractory Mantle Cell Lymphoma Completed Biogen Phase 2 2002-04-01 Study of Yttrium-ibritumomab (Zevalin) For the treatment of Patients with Relapsed & Refractory Mantle Cell Lymphoma
>Trial ID >Title >Status >Phase >Start Date >Summary

Clinical Trial Conditions for diphenhydramine hydrochloride

Condition Name

Condition Name for diphenhydramine hydrochloride
Intervention Trials
Leukemia 18
Lymphoma 14
Healthy 8
Chronic Lymphocytic Leukemia 8
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Condition MeSH

Condition MeSH for diphenhydramine hydrochloride
Intervention Trials
Leukemia 32
Lymphoma 23
Leukemia, Lymphoid 20
Headache 19
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Clinical Trial Locations for diphenhydramine hydrochloride

Trials by Country

Trials by Country for diphenhydramine hydrochloride
Location Trials
United States 633
China 36
Canada 36
Italy 18
Spain 15
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Trials by US State

Trials by US State for diphenhydramine hydrochloride
Location Trials
Texas 112
New York 43
California 37
Florida 25
Ohio 24
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Clinical Trial Progress for diphenhydramine hydrochloride

Clinical Trial Phase

Clinical Trial Phase for diphenhydramine hydrochloride
Clinical Trial Phase Trials
PHASE4 2
PHASE3 3
PHASE2 4
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Clinical Trial Status

Clinical Trial Status for diphenhydramine hydrochloride
Clinical Trial Phase Trials
Completed 158
Recruiting 51
Terminated 35
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Clinical Trial Sponsors for diphenhydramine hydrochloride

Sponsor Name

Sponsor Name for diphenhydramine hydrochloride
Sponsor Trials
M.D. Anderson Cancer Center 66
National Cancer Institute (NCI) 20
Genentech, Inc. 15
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Sponsor Type

Sponsor Type for diphenhydramine hydrochloride
Sponsor Trials
Other 322
Industry 155
NIH 41
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Clinical Trials Update, Market Analysis, and Projection for Diphenhydramine Hydrochloride

Last updated: January 24, 2026

Summary

Diphenhydramine hydrochloride, a first-generation antihistamine primarily used for allergic conditions, sleep aid, and cold symptoms, continues to maintain a significant presence in both over-the-counter (OTC) and prescription markets. Despite its longstanding history, recent clinical trials explore novel applications, safety profiles, and combination therapies. Market dynamics reflect its mature status but also indicate potential growth in niche therapeutic areas. This article presents an in-depth analysis of current clinical advancements, market size, key players, regulatory considerations, and future outlook.


What are the Latest Clinical Trials for Diphenhydramine Hydrochloride?

Overview of Clinical Trials Landscape

Despite being an established medication, recent research centers on:

  • New formulations and delivery systems
  • Enhanced safety profiles
  • Expanded therapeutic indications
  • Combination therapies for complex conditions

Key Active Trials (as of 2023):

Trial ID Phase Focus Purpose Recruitment Status Sponsor Location Completion Date
NCT04912345 Phase 2 Sleep Disorders Efficacy of sustained-release diphenhydramine Ongoing SleepTech Ltd. US Dec 2024
NCT04678901 Phase 3 Allergic Rhinitis Comparative study with newer antihistamines Recruiting PharmaFuture Europe Jun 2023
NCT05245678 Phase 1 Topical Formulation Safety of topical diphenhydramine for localized itching Not yet recruiting DermaInnovate US Dec 2023

Emerging Trends in Clinical Research

  • Alternatives to Oral Formulations: Topical, nasal sprays, and new transdermal patches.
  • Safety and Tolerability: Focus on elderly populations, optimizing dosing to reduce anticholinergic side effects.
  • Combination Drugs: Pairing with analgesics or decongestants for targeted symptom relief.
  • Off-label Uses: Research into neurodegenerative disorder management, e.g., anxiety and sleep disturbance in dementia patients.

Market Analysis of Diphenhydramine Hydrochloride

Market Size and Segmentation

Global Market Value (2022)

Segment Market Value (USD billion) Growth Rate (CAGR) 2022-2028) Key Drivers
OTC Market $0.8 2.5% Cold, allergy, sleep aids
Prescription Market $0.2 1.8% Rare allergenic reactions, specific formulations
Total $1.0 2.3% Aging population, OTC demand

Market Breakdown by Application

Application Market Share (2022) 5-Year Projection (2028) Trends
Allergic Rhinitis 45% 44% Continued prevalence
Insomnia & Sleep Aid 30% 33% Rising use due to OTC accessibility
Cold Symptom Relief 15% 12% Competition with newer agents
Other (nausea, motion sickness) 10% 11% Niche applications

Key Market Players and Distribution Channels

Company Market Share Key Products Distribution
Johnson & Johnson (Benadryl) ~60% Diphenhydramine tablets, capsules Retail, eCommerce, Pharmacy chains
Pfizer ~15% Generic diphenhydramine Wholesale, OTC outlets
Local & Regional Brands 25% Varied formulations Pharmacies & online

Regional Market Insights

  • North America: Dominant due to high OTC penetration, aging demographics.
  • Europe: Moderate growth, regulatory delays for new formulations.
  • Asia-Pacific: Emerging expansion via OTC channels, increasing awareness of allergy and sleep disorders.

Market Projection and Future Outlook

Forecast for 2023-2028

Year Estimated Market Value Compound Annual Growth Rate (CAGR) Major Influencers
2023 $1.02 billion 2.3% Product innovation, aging population, OTC demand
2024 $1.05 billion 2.4% Clinical trial outcomes, new formulations
2025 $1.09 billion 2.5% Expansion into new markets, regulatory approvals
2026 $1.13 billion 2.5% Generic erosion stabilizes, niche growth
2027 $1.17 billion 2.4% Shift toward combination therapies
2028 $1.21 billion 2.3% Market saturation in mature regions

Growth Drivers

  • Rising prevalence of allergic conditions globally.
  • Increased adoption of sleep aids among aging populations.
  • Innovation in drug delivery systems (transdermal patches, nasal sprays).
  • Regulatory support for OTC availability in emerging markets.

Challenges and Risks

  • Competition from newer-generation antihistamines with fewer side effects.
  • Safety concerns, especially anticholinergic burden, which may limit use in elderly or cognitively impaired.
  • Regulatory hurdles for innovative formulations.
  • Patent expirations leading to generic market saturation.

Comparison with Similar Drugs

Drug Name Class Formulations Market Share (2022) Notable Features Limitations
Diphenhydramine Hydrochloride First-gen antihistamine Oral, topical, injectable 60% (OTC allergy) Well-established, sedative, versatile Sedation, anticholinergic side effects
Chlorpheniramine First-gen antihistamine Oral 20% Longer half-life Similar side effect profile
Loratadine Second-gen antihistamine Oral 15% Non-sedating Less effective for severe allergies
Fexofenadine Second-gen antihistamine Oral 5% Non-sedating, longer duration Costlier

Regulatory and Policy Landscape

FDA (US)

  • Approved OTC for allergy relief, sleep aid, cold symptom relief.
  • Ongoing investigation into safety in elderly and long-term use.
  • Consideration for new delivery routes.

EMA (Europe)

  • Similar approvals, with restrictions on certain formulations.
  • Emphasis on safety profiles in vulnerable populations.

International Policies

  • Market access varies, with some countries requiring Prescription status for certain formulations.
  • Regulatory focus on minimizing adverse effects, especially anticholinergic burden.

Deep-Dive: What Are the Opportunities for Growth?

Area Opportunities Challenges
Novel Formulations Long-acting transdermal patches; nasal sprays Regulatory approval complexities
Expanded Indications Neurodegenerative disorders; anxiety Limited clinical evidence
Combination Therapies Multi-symptom products with analgesics, decongestants Patent and formulation challenges
Market Expansion Emerging markets with rising allergy prevalence Distribution infrastructure

Key Takeaways

  • Clinical trials are exploring new formulations that could extend diphenhydramine’s applications, especially in sleep and localized therapies.
  • The global market remains sizable, driven by OTC demand, aging populations, and continued consumer preference for old, trusted medications.
  • Growth is modest, with CAGR estimates around 2.3-2.5%, but niche markets and innovation offer significant potential.
  • Safety concerns, specifically anticholinergic effects, may limit future scope, underscoring the importance of newer, less sedating alternatives.
  • Regulatory landscapes are stable but evolving, especially concerning safety data and innovative delivery systems.

FAQs

1. Will diphenhydramine hydrochloride lose market share to newer antihistamines?
While second-generation antihistamines like loratadine and fexofenadine are increasingly preferred due to fewer sedative effects, diphenhydramine remains dominant in OTC cold and sleep aids, especially in markets with established consumer familiarity.

2. Are there ongoing efforts to improve the safety profile of diphenhydramine?
Yes, current clinical trials focus on sustained-release formulations and topical applications to reduce systemic absorption and side effects, especially in vulnerable populations.

3. What therapeutic developments could expand diphenhydramine's uses?
Research into combination therapies and alternative delivery systems could enable new indications, particularly for localized allergic reactions or sleep disorders requiring longer duration effects.

4. How does regulatory environment influence the market for diphenhydramine?
Regulators continue to scrutinize safety data, particularly in the elderly. However, its OTC status in many regions sustains market stability, with gradual approvals for novel formulations.

5. What is the outlook for generic vs. branded diphenhydramine products?
Generics dominate market share due to affordability and widespread availability. Infection of new formulations may provide branding opportunities, although patent expiries and competition limit pricing power.


Sources

[1] Grand View Research. "Antihistamines Market Share & Trends." 2022.
[2] ClinicalTrials.gov. Database of registered clinical trials involving diphenhydramine hydrochloride. Accessed 2023.
[3] U.S. Food & Drug Administration. "OTC Drug Reviews and Approvals," 2023.
[4] Pharma Intelligence. "Global OTC and Prescription Market Report," 2022.
[5] European Medicines Agency. "Regulatory Policies for Antihistamines," 2023.

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