Hydroxyzine vs Diphenhydramine: what is the difference?
Hydroxyzine and diphenhydramine, sold as Benadryl, both cause drowsiness, but hydroxyzine lasts longer, is prescription only and also treats anxiety.
Sources and notes
- The sentence under the titlefrom sourceMoleculeFinder comparison notesThe pair's answer line.
- The two drawingscomputedMoleculeFinder rule (RDKit MCS)Drawn the same way round on the skeleton they share. Aligned; 19 atoms differ, too many to mark as one group.
Side by side
| Hydroxyzine | Diphenhydramine | |
|---|---|---|
| Molecular weightCalculated PubChem | 374.9 g/molC21H27ClN2O2 | 255.35 g/molC17H21NO |
| Hydrogen-bond donorsCalculated PubChem | 1 | 0 |
| Where each turns upEditorial MoleculeFinder food and product lists | Not on our lists |
|
| Also sold asEditorial MoleculeFinder curated | Not recorded | Benadryl, ZzzQuil, Sominex |
| FamilyEditorial MoleculeFinder curated | Antihistamines | Over-the-counter medicines |
| Everyday groupEditorial MoleculeFinder curated | Prescription medicine | OTC medicine |
| Chemical groupsCalculated Found by rule (RDKit) | Alcohols, Aromatics, Ethers, Halogenated | Aromatics, Ethers |
| Hazard labelReported ECHA via PubChem | Danger | Warning |
| The supplier-filed hazard label's signal word, not a statement about ordinary use. | ||
| Oral LD50Measured HSDB via PubChem | 840 mg/kgpure hydroxyzine, rat, oral | Not recorded |
| A single acute animal measure. It ranks nothing about human safety. | ||
Sources and notes
- Molecular weightcomputedPubChemComputed from the structure; the formula is under each weight.
- Hydrogen-bond donorscomputedPubChemThe hydrogens on nitrogen or oxygen that each molecule can lend to a hydrogen bond, counted from its structure.
- Where each turns upfrom sourceMoleculeFinder food and product listsEach amount is an editorial figure from our lists, not a measurement of any one product. Each mark is set by hand on the list, never inferred.
- Also sold asfrom sourceMoleculeFinder curated
- Familyfrom sourceMoleculeFinder curated
- Everyday groupfrom sourceMoleculeFinder curated
- Chemical groupscomputedFound by rule (RDKit)Each group is found in the structure by a chemical pattern.
- Hazard labelfrom sourceECHA via PubChem
- Oral LD50from sourceHSDB via PubChem
- ECHAfrom sourceAttributionSource: European Chemicals Agency, echa.europa.eu.
- Identifiersfrom sourcePubChemPubChem CID 3658 (Hydroxyzine) and 3100 (Diphenhydramine).
In more detail
Both are first generation antihistamines that cross into the brain, and they are used for noticeably different things. Diphenhydramine is an over-the-counter allergy medicine and sleep aid with a short duration, a few hours. Hydroxyzine lasts much longer, is prescription-only in the United States and the United Kingdom, and is used for anxiety and itching as well as allergy, partly because it also acts on serotonin receptors. Hydroxyzine is the heavier molecule at 374.9 against 255.35 and carries a piperazine ring where diphenhydramine has a simple dimethylamine. Cetirizine, the common non-drowsy antihistamine, is actually hydroxyzine's own metabolite with that ring capped by a carboxylic acid.
Sources and notes
- The paragraphfrom sourceMoleculeFinder comparison notes
Questions
- What is the difference between Hydroxyzine and Diphenhydramine (Benadryl)?
- Hydroxyzine and diphenhydramine, sold as Benadryl, both cause drowsiness, but hydroxyzine lasts longer, is prescription only and also treats anxiety.
- Is Hydroxyzine bigger than Diphenhydramine?
- Hydroxyzine is the heavier molecule, 374.9 g/mol against 255.35 g/mol for Diphenhydramine. Hydroxyzine is C21H27ClN2O2 and Diphenhydramine is C17H21NO.
Sources and notes
- The answersfrom sourceMoleculeFinderThe first is the pair's answer line; the others are read off the table above.