List of Excipients in Branded Drug DIPHENHYDRAMINE HYDROCHLORIDE

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Generic Drugs Containing DIPHENHYDRAMINE HYDROCHLORIDE

Company	Ingredient	NDC	Excipient
PAI Holdings LLC dba PAI Pharma	diphenhydramine hydrochloride	0121-0489	ALCOHOL
PAI Holdings LLC dba PAI Pharma	diphenhydramine hydrochloride	0121-0489	ANHYDROUS CITRIC ACID
PAI Holdings LLC dba PAI Pharma	diphenhydramine hydrochloride	0121-0489	D&C RED NO. 33
PAI Holdings LLC dba PAI Pharma	diphenhydramine hydrochloride	0121-0489	FD&C RED NO. 40

What are the Most Frequently-Used Excipients in DIPHENHYDRAMINE HYDROCHLORIDE?

# Of NDCs	Excipient
3	ALCOHOL
1	ANHYDROUS CITRIC ACID
2	ANHYDROUS LACTOSE
18	BENZETHONIUM CHLORIDE

Diphenhydramine Hydrochloride Excipient Strategy and Commercial Opportunities

Last updated: October 21, 2026

Diphenhydramine hydrochloride is a mature, low-cost first-generation antihistamine with broad OTC use in allergy, cough-and-cold, nighttime sleep, and topical products. Its core active-ingredient patent protection has expired, and commercial value now depends on formulation performance, consumer positioning, manufacturing efficiency, regulatory compliance, and retail distribution.

The strongest excipient opportunities are in alcohol-free pediatric liquids, sugar-free and dye-free products, taste-masked chewables, rapid-disintegration tablets, softgels, topical systems, and differentiated combination products. The main technical constraints are bitter taste, sedation, dose accuracy, chemical stability, microbial control in aqueous products, and the need to avoid excipient-driven increases in abuse or overdose risk.

What is diphenhydramine hydrochloride used for?

Diphenhydramine hydrochloride is an H1 antihistamine with anticholinergic and sedative effects. It is marketed in several product categories:

Product category	Typical dosage form	Commercial use
Allergy relief	Tablets, capsules, liquids, chewables	Sneezing, runny nose, itching
Nighttime sleep aids	Tablets, capsules, softgels, liquids	Occasional sleeplessness
Cough-and-cold combinations	Liquids, tablets, capsules	Multi-symptom relief
Topical antipruritic products	Creams, gels, sprays	Localized itching and insect bites
Pediatric products	Liquids, chewables, dissolving tablets	Age-appropriate allergy relief
Combination analgesics	Tablets, caplets, liquid products	Nighttime pain and cold relief

The FDA recognizes diphenhydramine as an OTC oral antihistamine active ingredient and as a topical external analgesic or antipruritic active ingredient under separate monograph frameworks. Oral labeling includes warnings related to drowsiness, alcohol, sedatives, driving, and use in children. The FDA has also warned against administering cough-and-cold products containing antihistamines to children younger than two years unless directed by a health professional. (FDA, 2023; 21 C.F.R. §§ 341, 346)

What excipients are used in diphenhydramine hydrochloride products?

Diphenhydramine hydrochloride formulations commonly use excipients in five functional groups: fillers, binders, disintegrants, taste-masking agents, and preservation or stability systems.

Oral tablets and caplets

Immediate-release tablets commonly use:

• Microcrystalline cellulose as a filler and dry binder
• Lactose monohydrate, mannitol, or dibasic calcium phosphate as diluents
• Croscarmellose sodium, sodium starch glycolate, or crospovidone as disintegrants
• Povidone as a binder
• Magnesium stearate or stearic acid as lubricants
• Colloidal silicon dioxide as a glidant
• Hypromellose, polyethylene glycol, titanium dioxide, and iron oxides for film coating

The preferred platform depends on target cost, tablet size, hardness, friability, disintegration time, and brand positioning. Lactose-based systems are economical but exclude consumers avoiding dairy-derived excipients. Mannitol-based systems improve mouthfeel and support chewable or orally disintegrating formats, but they increase cost and may create a cooling sensation or gastrointestinal tolerance issues at higher levels.

Capsules and softgels

Hard-shell capsules can reduce tablet compression problems and allow faster development. Typical excipient systems include microcrystalline cellulose, starch, magnesium stearate, and colloidal silicon dioxide.

Softgels require a different approach. Diphenhydramine hydrochloride is a water-soluble salt, so an aqueous or hydroalcoholic fill may be more practical than a conventional lipid fill. The formulation must manage shell compatibility, water migration, fill viscosity, sealing, and long-term stability. A softgel can provide a premium consumer presentation, but manufacturing cost and scale-up complexity are higher than for tablets.

Oral liquids

Liquid products provide the strongest excipient differentiation opportunities because they address swallowing difficulty, pediatric dosing, and consumer preference.

Common components include:

• Purified water as the vehicle
• Glycerin, sorbitol, or propylene glycol for sweetness, viscosity, and solubilization
• Sucrose in conventional syrups
• Sucralose, saccharin sodium, or acesulfame potassium in sugar-free products
• Citric acid and sodium citrate for pH adjustment and flavor balance
• Sodium benzoate or potassium sorbate for preservation
• Flavor systems, including grape, cherry, berry, or fruit blends
• Polysorbates or other solubilizers when required
• Coloring agents, where used

Diphenhydramine hydrochloride is bitter, so flavor alone may not deliver adequate palatability. A commercial formulation may require a combination of pH control, sweetener selection, viscosity modification, flavor layering, and taste-masking polymers. Excessive sweetness can create pediatric compliance and dental concerns, while excessive viscosity can impair dose delivery through oral syringes.

Alcohol-free formulations are commercially attractive because they address parent and caregiver concerns. Sugar-free formulations also support diabetic-friendly positioning and reduce the need for sugar-related labeling. Dye-free products can target consumers seeking simpler formulations and reduce the risk of concerns about artificial colors.

Chewable and orally disintegrating tablets

Chewable products require careful control of:

• Bitter taste release
• Tablet hardness
• Friability
• Mouthfeel
• Residual grittiness
• Sweetener stability
• Flavor persistence

Mannitol, xylitol, sorbitol, and compressible sugars can support chewable performance. Crospovidone or low-substituted hydroxypropyl cellulose can accelerate disintegration in orally disintegrating tablets. Ion-exchange resins, polymeric coatings, cyclodextrins, and lipid-based barriers may be used for taste masking.

Xylitol provides strong consumer appeal but can create gastrointestinal effects at higher intake levels and is highly toxic to dogs. Product labeling, manufacturing controls, and household-use considerations are relevant for pet-owning consumers.

Topical creams, gels, and sprays

Topical diphenhydramine hydrochloride products typically require:

• Water or hydroalcoholic vehicle
• Carbomer or cellulose-based rheology modifiers
• Propylene glycol or glycerin as humectants and penetration aids
• Neutralizers such as tromethamine or sodium hydroxide
• Preservatives such as parabens, phenoxyethanol, or benzoates
• Emulsifiers and emollients in cream systems

Topical products must balance spreadability, drying time, skin feel, drug release, and irritation potential. A gel can offer fast drying and a non-greasy profile. A cream can provide longer residence time and a more moisturizing consumer experience. Hydroalcoholic sprays can improve convenience but may cause stinging on damaged skin.

Which excipient strategies create the strongest commercial opportunities?

The highest-value opportunities are those that solve a recognizable consumer problem while remaining compatible with OTC labeling and scalable manufacturing.

Opportunity	Excipient strategy	Commercial rationale
Dye-free allergy product	No synthetic colorants; neutral flavor and coating system	Parent and clean-label demand
Alcohol-free liquid	Water, glycerin, sorbitol, approved preservative system	Pediatric and caregiver acceptance
Sugar-free syrup	Polyols plus high-intensity sweeteners	Diabetic-friendly and lower-sugar positioning
Taste-masked chewable	Polymer coating, resin complex, flavor-sweetener system	Improved adherence and convenience
Rapid-dissolving tablet	Mannitol, crospovidone, low-moisture process	No-water dosing and portability
Premium softgel	Controlled aqueous or mixed solvent fill	Differentiated sensory and brand presentation
Low-cost generic tablet	Direct compression with robust excipient platform	Margin protection and supply efficiency
Gentle topical gel	Carbomer or cellulose gel with reduced alcohol	Sensitive-skin and non-greasy positioning
Dual-format family line	Tablets, liquid, and topical products using common brand architecture	Retail shelf expansion

The most defensible commercial claims generally relate to format, sensory performance, excipient exclusion, delivery convenience, or manufacturing quality. Claims that imply superior antihistamine efficacy require appropriate clinical and regulatory support.

What formulations are protected by diphenhydramine patents?

Diphenhydramine hydrochloride has no meaningful remaining composition-of-matter exclusivity in the United States. The active ingredient has been marketed for decades, and ordinary immediate-release tablets, capsules, liquids, and topical products are generally exposed to generic and private-label competition.

Potentially protectable subject matter may include:

• Specific taste-masking systems
• Novel orally disintegrating compositions
• Controlled-release dosage forms
• Stable aqueous formulations
• Low-alcohol or alcohol-free liquid systems
• Transdermal or topical delivery systems
• Combination products
• Manufacturing processes that improve uniformity or yield
• Packaging systems that improve moisture or light protection
• Pediatric dosing systems

Patent strength depends on claim breadth, demonstrated technical effect, prior-art density, enablement, and commercial relevance. A narrow formulation patent covering a specific polymer ratio or manufacturing sequence may be enforceable but commercially weak if competitors can design around it. A stronger estate would combine composition claims, process claims, dosage-form claims, and product-by-process or packaging claims where legally supportable.

When does diphenhydramine hydrochloride lose exclusivity?

Diphenhydramine hydrochloride has already lost practical exclusivity in the United States. It is a mature OTC active ingredient with multiple manufacturers and private-label products.

Exclusivity category	Current position
Composition-of-matter patent	Expired or commercially irrelevant
Core active-ingredient exclusivity	None
FDA new-drug exclusivity	Not a meaningful barrier for standard OTC products
OTC monograph access	Available for compliant products
Generic competition	Extensive
Formulation protection	Potentially available only for specific innovations
Orange Book barrier	Generally limited for ordinary OTC products

The FDA Orange Book primarily identifies approved drug products and associated patents for products approved through the new drug application pathway. Many OTC monograph products do not present the same Orange Book patent framework as prescription drugs. An NDA-based diphenhydramine product could have listed patents, but ordinary monograph-compliant products generally do not depend on branded patent exclusivity. (FDA, 2024a)

What is the FDA regulatory status of diphenhydramine hydrochloride?

Diphenhydramine hydrochloride is used in FDA-regulated OTC products under monograph conditions for specified indications, dosage forms, labeling, and concentrations. Products must comply with applicable active-ingredient requirements and the general OTC framework under the Federal Food, Drug, and Cosmetic Act and the final monograph regulations.

Regulatory attention should focus on:

• Correct active-ingredient concentration
• Age-based dosing
• Warning language
• Measuring-device accuracy for liquids
• Preservative effectiveness
• Microbial limits
• Child-resistant packaging where applicable
• Excipient safety and permissible use levels
• Drug Facts labeling
• Combination-product compatibility
• Stability through labeled shelf life

A liquid product may require more extensive development work than a tablet because microbial control, preservative effectiveness, pH drift, flavor stability, and dosing-device performance all affect commercial release.

How should manufacturers select excipients for diphenhydramine products?

Manufacturers should rank excipients against five decision criteria:

1. Regulatory acceptability at the intended route and concentration
2. Taste and sensory performance
3. Chemical and physical stability
4. Manufacturing robustness
5. Cost and supply-chain resilience

The FDA Inactive Ingredient Database provides a useful starting point for evaluating prior use by route and dosage form, but prior use does not eliminate the need for product-specific safety, compatibility, and quality assessment. (FDA, 2024b)

Key compatibility risks

Diphenhydramine hydrochloride formulation development should evaluate:

• pH-dependent solubility and degradation
• Interaction with reducing sugars
• Moisture uptake in hygroscopic excipients
• Lubricant effects on dissolution
• Adsorption to packaging or dosing components
• Preservative partitioning into surfactant or flavor systems
• Color or flavor instability
• Polymer-drug interactions in taste-masked systems
• Gel viscosity drift over shelf life

High-moisture excipients can create tablet stability problems. Excessive magnesium stearate can slow wetting and dissolution. Surfactants can improve wetting but may also alter preservative performance or produce undesirable mouthfeel.

Which companies are challenging diphenhydramine hydrochloride products?

Competition is broad and fragmented. The market includes branded OTC manufacturers, generic drug companies, contract manufacturers, pharmacy chains, mass retailers, and private-label distributors.

Representative competitive groups include:

• Kenvue and legacy Benadryl-branded products
• Perrigo generic and private-label products
• Haleon and other consumer-health companies in adjacent nighttime and cough-and-cold categories
• Retailer-owned brands
• Contract development and manufacturing organizations
• International OTC manufacturers

Competitive advantage is usually created through distribution, price, product reviews, packaging, line extensions, and supply reliability rather than active-ingredient exclusivity.

What generic launch risks exist for diphenhydramine products?

Generic launch risk is high for conventional tablets and capsules because manufacturing processes are well established and the active ingredient is inexpensive. The principal barriers are commercial rather than patent-based.

High-risk segments

• Standard 25 mg tablets
• Standard 25 mg capsules
• Conventional liquid products
• Basic topical creams

Moderate-opportunity segments

• Alcohol-free pediatric liquids
• Sugar-free or dye-free liquids
• Chewable tablets
• Fast-dissolving tablets
• Improved dosing-device systems

Higher technical-barrier segments

• Taste-masked products with demonstrated sensory superiority
• Long-acting formulations
• Novel topical delivery systems
• Stable combination products
• Premium softgels
• Products requiring specialized coating or encapsulation equipment

A generic entrant can usually avoid patent exposure by using a conventional excipient system. A differentiated entrant needs a specific technical advantage, such as reduced bitterness, faster disintegration, improved stability, or a meaningful consumer-use benefit.

What licensing opportunities exist for diphenhydramine formulations?

Licensing opportunities are more likely to involve platform technology than the active ingredient itself. Potentially valuable assets include:

• Taste-masking technology applicable to bitter antihistamines
• Orally disintegrating tablet platforms
• Pediatric liquid preservation systems
• Unit-dose liquid packaging
• Low-moisture direct-compression technology
• Topical gel or film systems
• Combination-product formulation know-how
• Drug-device systems for accurate pediatric dosing

A licensee would likely prioritize technologies that can be reused across multiple OTC actives. A diphenhydramine-only license has limited strategic value unless it covers a commercially important format, has clear freedom-to-operate advantages, or supports a differentiated brand launch.

What manufacturing and intellectual-property barriers affect diphenhydramine?

Manufacturing barriers are modest for conventional tablets but increase for liquids, taste-masked products, and specialized delivery systems.

Important barriers include:

• Uniformity of low-dose blends
• Powder flow and segregation control
• Film-coating reproducibility
• Flavor and preservative compatibility
• Microbial control in aqueous products
• Softgel fill and shell compatibility
• Taste-masking process control
• Equipment qualification
• Packaging-barrier performance
• Scale-up from laboratory to commercial batch size

The strongest IP strategy usually combines formulation claims with process controls and packaging claims. A formulation that cannot be reproduced consistently at commercial scale has limited business value even if its patent claims appear broad.

How does diphenhydramine compare with competing antihistamines?

Diphenhydramine competes with newer antihistamines such as cetirizine, loratadine, and fexofenadine, which are generally positioned around reduced sedation or once-daily dosing. Diphenhydramine retains advantages in brand recognition, low cost, broad availability, and established use in nighttime products.

Attribute	Diphenhydramine	Cetirizine	Loratadine	Fexofenadine
Sedation concern	High	Moderate in some users	Generally lower	Generally lower
Typical dosing frequency	Multiple daily doses	Usually once daily	Usually once daily	Usually once or twice daily
Mature generic supply	Extensive	Extensive	Extensive	Extensive
Strong nighttime positioning	Yes	Limited	Limited	Limited
Pediatric liquid opportunity	High	High	High	High
Formulation differentiation	Taste, delivery, combination use	Taste and dosing convenience	Taste and pediatric delivery	Solubility and dosing convenience

Diphenhydramine’s sedation profile limits its suitability for daytime allergy products but supports nighttime and sleep-related positioning. Regulatory and commercial teams must manage labeling carefully because misuse and excessive dosing can produce serious adverse effects.

What is the commercial outlook for diphenhydramine excipient innovation?

The commercial outlook is strongest in product renovation rather than basic generic substitution. A manufacturer can create value through:

• Better palatability
• Fewer excipients of consumer concern
• Alcohol-free and dye-free positioning
• Accurate pediatric dosing
• Convenient no-water formats
• Improved topical sensory properties
• Stable, low-cost liquid systems
• Retailer-exclusive or private-label formulations

Revenue exposure for a diphenhydramine product is driven by unit volume, retail placement, brand strength, seasonal demand, and price realization. The active ingredient contributes little differentiation. Excipient strategy affects conversion, repeat purchase, manufacturing yield, complaint rates, and product reviews.

Key Takeaways

• Diphenhydramine hydrochloride has no meaningful remaining core patent exclusivity.
• Conventional tablets, capsules, liquids, and creams face intense generic and private-label competition.
• The strongest commercial opportunities are alcohol-free liquids, sugar-free products, dye-free products, taste-masked chewables, orally disintegrating tablets, softgels, and improved topical systems.
• Taste masking, preservative compatibility, microbial control, and pediatric dosing accuracy are major formulation-development issues.
• OTC monograph compliance is more important than Orange Book patent strategy for most standard products.
• Valuable licensing targets are reusable formulation and delivery platforms rather than diphenhydramine-specific active-ingredient rights.
• A defensible patent estate should combine formulation, process, delivery, and packaging claims where the technical evidence supports them.
• Sedation and overdose warnings constrain product positioning and require careful labeling and consumer communication.

FAQs

Is diphenhydramine hydrochloride still patent protected?

The active ingredient is not commercially protected by an active composition-of-matter patent. Specific formulation, delivery, combination, process, or packaging inventions may have separate patent rights.

What is the best excipient for masking diphenhydramine taste?

No single excipient is universally optimal. Effective systems often combine polymeric or resin-based taste masking with mannitol or another mouthfeel modifier, high-intensity sweeteners, pH control, and a persistent flavor system.

Can diphenhydramine hydrochloride be formulated without alcohol?

Yes. Alcohol-free oral liquids can use purified water, glycerin, sorbitol, approved sweeteners, flavors, and a suitable preservative system. The formulation must maintain solubility, palatability, microbial quality, and stability.

Is diphenhydramine hydrochloride listed in the Orange Book?

Some NDA-approved products may have Orange Book records, but ordinary OTC monograph products generally do not rely on Orange Book-listed patent protection in the same manner as branded prescription products.

Which diphenhydramine dosage form has the best commercial potential?

Taste-masked pediatric liquids, dye-free and alcohol-free products, chewables, orally disintegrating tablets, and differentiated topical gels offer greater commercial potential than standard immediate-release tablets because they address usability and consumer-preference gaps.

References

1. Code of Federal Regulations. (2024a). 21 C.F.R. Part 341: Cold, cough, allergy, bronchodilator, and antiasthmatic drug products for over-the-counter human use. U.S. Government Publishing Office.

2. Code of Federal Regulations. (2024b). 21 C.F.R. Part 346: External analgesic drug products for over-the-counter human use. U.S. Government Publishing Office.

3. U.S. Food and Drug Administration. (2023). Use caution when giving cough and cold products to kids. https://www.fda.gov

4. U.S. Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

5. U.S. Food and Drug Administration. (2024b). Inactive Ingredient Database. https://www.accessdata.fda.gov/scripts/cder/iig/

6. U.S. Pharmacopeial Convention. (2024). United States Pharmacopeia and National Formulary. U.S. Pharmacopeial Convention.