Article: Cetirizine

Systematic (IUPAC) name
piperazin-1-yl]ethoxy]acetic acid
CAS number 83881-51-0
ATC code R06AE07
PubChem 2678
DrugBank APRD00630
Chemical data
Formula C21H25N2ClO3 
Mol. weight 388.888
Pharmacokinetic data
Bioavailability  ?
Metabolism CYP3A4
Half life 8.3 Hours
Excretion Hepatic
Therapeutic considerations
Pregnancy cat.


Legal status

Rx-only, OTC in Canada and UK

Routes Oral

Cetirizine hydrochloride is a medication used for the treatment of allergies, hay fever, angioedema, and hives. It is a second-generation H1-receptor antagonist antihistamine and works by blocking H1 histamine receptors. It is a major metabolite of hydroxyzine, and has the same basic side effects, including dry mouth.

  • It has long duration of action
  • No reported cardiotoxicity associated with the use of this drug
  • Minimal penetration of the blood-brain barrier
  • Only mild sedating effects, although more than some other non-sedating antihistamines

Brand Names

The medication is produced by UCB, a Belgian pharmaceutical company. The drug is marketed under the following brand names:

  • Zyrtec in the USA
  • Zirtek, Zynor and generically in the United Kingdom
  • Zyrlex in many other European countries
  • Reactine in Canada (as well as generically) and Europe (all by Pfizer [1])
  • Benaday and generic Cetirizin in Denmark
  • Virlix in Mexico and parts of Europe (by GlaxoSmithKline [2])
  • Humex in France

It can be found under a variety of other brand names in other countries [3].


Like many other antihistamine medications, cetirizine is commonly prescribed in combination with pseudoephedrine hydrochloride, a decongestant. These combinations are marketed using the same brand name as the cetirizine with a "-D" suffix (Zyrtec-D, Virlix-D, etc.)