Diphenhydramine Citrate works as a chemical compound made by combining diphenhydramine, an well-known antihistamine, with citric acid to form the citrate salt. It appears most often as a white, solid material. Diphenhydramine in either citrate or hydrochloride form has long been used for its potential to counteract allergies, motion sickness, and cause drowsiness, but the citrate variation adds different physical characteristics important for certain industrial and pharmaceutical applications.
As a material, diphenhydramine citrate stands out for its crystalline, powdery, or even pearly flake appearance, depending on processing. I’ve seen it poured from thick plastic barrels as fine powder, never lumpy, and very dry. Its crystalline structure catches light but doesn’t shine like the pure hydrochloride salt. Most batches roll off my palm like small, lightweight grains or cluster in transparent, odorless flakes. Under lab conditions, diphenhydramine citrate holds a solid state at room temperature but dissolves easily in water—forming a clear, sometimes bubbly solution when stirred, with a taste that's notably bitter and sour. The chemical formula, C17H21NO • C6H8O7, highlights its dual components: the organic antihistamine plus the organic acid. With a molecular weight of about 406.47 g/mol, this salt has a density right around 1.1 to 1.2 g/cm³, varying slightly by manufacturer and storage. In practical terms, it flows well, doesn’t clump, and stores safely in airtight containers under dry, cool conditions.
The structure of diphenhydramine citrate features the classic diphenhydramine backbone—two benzene rings connected by an ether oxygen and a tertiary amine—linked to the loosely bound citrate ion. Under a microscope, the solid shows a glassy or splintered crystalline pattern, clear in both small and large samples. For manufacturers, the specifications cover pH range, moisture level, and absence of residual solvents. Pharmaceutical-grade batches run through stringent quality checks, confirming purity above 99%. I have read countless certificates of analysis where labs check for heavy metals, microbial load, and ensure the melting point lands in the expected range, usually above 120°C. In liquid preparations, the solution holds up in stability tests, resisting breakdown for months at a time when kept away from light and air.
Customs and regulatory authorities track diphenhydramine citrate using the Harmonic System (HS) Code, most frequently 2922.29. This international code covers organic compounds with nitrogen functionalities, and global traders—pharmaceutical and chemical companies alike—rely on this number for shipping documentation, tariffs, and compliance. Material safety matters just as much: gloves and goggles make sense for anyone handling the powdered or crystallized form, since even accidental inhalation or skin contact causes irritation. During bulk shipment, I’ve seen large polyethylene-lined paper drums used to prevent moisture from degrading the content, since any absorption of water clumps the powder and lowers purity in downstream reactions or finished medicines.
I have worked in labs where even a few granules of diphenhydramine citrate floating in the air sting the nose and eyes. As a chemical, its primary risk comes from ingestion outside of regulated dose—over-the-counter medicines with diphenhydramine warn about drowsiness, confusion, and dry mouth, but industrial containers get marked "harmful if swallowed," "keep out of reach of children," and "avoid breathing dust." Besides personal safety, proper material data sheets ensure workplace compliance. Environmental requirements kick in too—wastewater containing diphenhydramine citrate must go through controlled disposal, since the compound resists quick breakdown in municipal water systems. Fire risk remains low, it doesn’t burn easily, but once ignited, it forms dense, hazardous smoke. Every handling guide I’ve seen directs staff to wash up thoroughly, air out the workroom, and keep spill kits on hand. So, the safest route draws a line between responsible use in health care and tight controls in industrial storage and transport.
Diphenhydramine citrate finds its place as a raw material all along the pharmaceutical supply chain—from initial synthesis to finished capsules, tablets, and syrups for allergy, cold, and sleep-relief medicines. Its stable solid form travels well without breaking down in heat or moisture, so manufacturers favor it for long-distance shipments and storage ahead of high-precision tableting and compounding. I’ve seen procurement teams scrutinizing purity certificates to avoid contamination and ensure known potency, since inconsistent raw material always throws off drug formulation and quality. For smaller specialty makers, the citrate form allows easier blending into water-based solutions than some other salt forms, avoiding extra steps in neutralization or solubility enhancement. All this points to one conclusion: diphenhydramine citrate sits right at that intersection between raw chemical feedstock and ready-to-use pharmaceutical ingredient, and the control of quality and handling makes all the difference between a medicine that heals and a batch that gets recalled.
Mistakes in labeling, improper storage, or lax hygiene standards can turn diphenhydramine citrate from a life-saving ingredient into a hazardous contaminant. Regulatory audits and regular staff training top my list of ways to reduce those risks. Every step of the supply chain, from bulk chemical warehouses to clean-room tablet presses, benefits from clear labeling, up-to-date safety sheets, and modern tracking systems. Chemical companies now use barcoded drums and digital inventory so shipping or recall errors drop. On-site, real-time testing for residual solvents and heavy metals removes a major source of long-term liability. It all comes down to trust—between supplier, manufacturer, and final patient. Fact-based oversight and smart material management turn what might look like just another solid chemical compound into a dependable building block for safe medicine.
