moleculefinder

Levocetirizine

C21H25ClN2O3388.9 g/mol Calculated

Also called Xazal.

The active mirror-image half of cetirizine, sold over the counter as Xyzal for hay fever and hives. Levocetirizine (C21H25ClN2O3, 389 g/mol) is an antihistamine sold over the counter.

Sources and notes
  • The introductionfrom sourceMoleculeFinder curated
  • Other namesfrom sourcePubChem / Wikidata
  • Formula and weightcomputedPubChem
  • 2D drawingcomputedPubChem structure, drawn by RDKit
  • 3D modelfrom sourcePubChem 3D conformerLoaded after the page has painted, and on a phone only when you ask for it; the 2D drawing shows until it arrives.

Where you encounter it

Sold over the counter, without a prescription. Levocetirizine on the product labels we hold.

Medicines

Xyzal Allergy 24HrAdded by the makerActive ingredient, 5 mg in each tablet

Every product and list we hold

Sources and notes
  • The product labels and their strengthsfrom sourceDailyMed (FDA label)Each label lists the molecule as an ingredient, and an active ingredient at the strength shown.
  • How it gets therefrom sourceMoleculeFinder curatedEach mark is set by hand on our lists, never inferred; a label's ingredient is added by the maker. A row with no mark data says Not marked.
  • The line abovefrom sourceMoleculeFinder curatedFrom the group the molecule belongs to.

Explore its structure

Choose a part to light it up.

A carbon carrying both a C=O and an O-H, written COOH. In water it gives up that hydrogen, which is what makes the molecule an acid.

From: standard chemistry.

Sources and notes
  • The drawingcomputedPubChem structure, drawn by RDKitThe page's one shipped drawing, with the chosen part lit in amber under it.
  • The partscomputedFound by ruleEach part is found by a chemical pattern, never picked by hand atom by atom; its words say where they come from.

Compare a related molecule

Levocetirizine

Cetirizine

The same atoms; levocetirizine is one mirror-image form, cetirizine a mix of both.

Cetirizine is a mix of two mirror-image forms and levocetirizine is the active one alone, so it works at about half the amount for a similar effect.

Levocetirizine vs Cetirizine, side by side
Sources and notes
  • The sentencefrom sourceMoleculeFinder comparison notesThe pair's answer line.
  • The two drawingscomputedPubChem structures, drawn by RDKitDrawn the same way round; the amber marks where the two differ.
  • The captionfrom sourceMoleculeFinder curated

Properties and sources

Calculated by PubChem

Molecular formula
C21H25ClN2O3
Molecular weight
388.9 g/mol
XLogP3octanol/water, log units
1.7
Polar surface areatopological
53 Ų
H-bond donors
1
H-bond acceptors
5
Rotatable bonds
8
Complexity
443

Reported Licence

The US Food and Drug Administration licenses Levocetirizine for human use (NDA 209089, authorized January 31, 2017), as Xyzal Allergy 24Hr. Drugs@FDA

Groups it belongs to

Category
OTC medicine
Family
Antihistamines
Use
Allergy
Chemical groups
Carboxylic Acids, Aromatics, Ethers, Halogenated
Elements
Chlorine, Nitrogen
SMILESC1CN(CCN1CCOCC(=O)O)[C@H](C2=CC=CC=C2)C3=CC=C(C=C3)Cl

PubChem CID 1549000 · Wikidata Q421091 · InChIKey ZKLPARSLTMPFCP-OAQYLSRUSA-N · Data refreshed

How MoleculeFinder sources and labels its data

Questions
What is Levocetirizine?
The active mirror-image half of cetirizine, sold over the counter as Xyzal for hay fever and hives. Levocetirizine (C21H25ClN2O3, 389 g/mol) is an antihistamine sold over the counter.
What kind of molecule is Levocetirizine?
Levocetirizine has the formula C21H25ClN2O3 and a molecular weight of 388.9 g/mol. MoleculeFinder files it under antihistamines, in the OTC medicine group. from sourcefrom sourcefrom sourcefrom source
Who licenses Levocetirizine as a medicine?
The US Food and Drug Administration licenses Levocetirizine for human use (NDA 209089, authorized January 31, 2017), as Xyzal Allergy 24Hr. from source
Sources and notes
  • Calculated valuescomputedPubChemComputed from the structure, so no laboratory conditions apply; complexity is PubChem's own structural score.
  • Licencefrom sourceDrugs@FDARead 2026-10-21.
  • Data refreshedfrom sourceMoleculeFinder2026-11-09

Keep exploring

The same atoms; levocetirizine is one mirror-image form, cetirizine a mix of both.CetirizineC21H25ClN2O3Also an antihistamineHydroxyzineC21H27ClN2O2Both carry an aromatic ring and a halogen atom.MeclizineC25H27ClN2Both carry an aromatic ring.CyclizineC18H22N2
Sources and notes
  • A group apartfrom sourceMoleculeFinder comparison captions
  • The same kind of moleculefrom sourceMoleculeFinder curated groupsA structural neighbour in the same family or type group; the line names the group in its own words.
  • Similar in shapecomputedRDKit Morgan/TanimotoNeighbours by structural fingerprint; the sentence names the chemical groups the two share.
  • The drawingscomputedPubChem structures, drawn by RDKit