8cited
checked 2026-08-05
what it isCheap once daily antihistamine and a reasonable default for hay fever or hives, though it is not quite as non sedating as its category name implies, and stopping abruptly after long use can set off weeks of intense itch
what it doesActs as an inverse agonist / antagonist at Histamine H1 receptor (HRH1), one of 4 targets.what you would noticeControls hives and chronic urticariaThe cheap default newer drugs must earn pastWorks even better taken ahead of exposure
is it safecetirizine is a single molecule in the antihistamine classin its favour: human data in the cited literaturenot settled: no published dosing range
Anti-inflammatoryImmune
classAntihistamine · Non-Sedative
key targetHistamine H1 receptor (HRH1) · Inverse agonist / antagonist; cetirizine is the racemate and levocetirizine is the active eutomer · Strong
targets4
literature1993 to 2026 · 6 journals
also known asZyrtec, Zodak, Cetrin, Solonex and 4 more
outlets1 outlet
see alsoLevocetirizine isomer
spec sheet8 rows
classAntihistamine · Non-Sedative
key targetHistamine H1 receptor (HRH1) · Inverse agonist / antagonist; cetirizine is the racemate and levocetirizine is the active eutomer · Strong
targets4
literature1993 to 2026 · 6 journals
also known asZyrtec, Zodak, Cetrin, Solonex and 4 more
outlets1 outlet
see alsoLevocetirizine isomer
all namesZyrtec, Zodak, Cetrin, Solonex, Reactine, Alerid, cetirizine hydrochloride, cetirizine dihydrochloride
evidence over time
19932 in 20002026
Cetirizine is a second generation H1 antihistamine taken once daily for hay fever, hives and other histamine driven allergy symptoms.
works for
- Once daily relief for hay fever and allergy symptoms
- Controls hives and chronic urticaria
- The cheap default newer drugs must earn past
- Works even better taken ahead of exposure
- Months of daily use is an accepted approach
- Second generation H1 blocker, one small tablet
Gallery
did you know
- Cetirizine is the carboxylated metabolite of hydroxyzine, which is why it retains full peripheral H1 potency while losing most of the parent's CNS penetration.
- It is a racemate and levocetirizine is the eutomer: essentially all the antihistaminic activity resides in the R-enantiomer, which does not racemise in vivo and has a smaller volume of distribution and lower non-renal clearance than dextrocetirizine [5].
- ETAC, an 18-month placebo-controlled trial in 817 infants with atopic dermatitis, is the landmark study; it did not prevent asthma overall but showed a reduction in asthma onset in the subgroup sensitised to grass pollen or house dust mite (PMID 9814724, PMID 12390444, PMID 11742270).
- Cetirizine is only minimally metabolised and is largely renally excreted unchanged, so it has few CYP-mediated interactions but does need dose reduction in renal impairment.
- Unlike terfenadine and astemizole, cetirizine has no clinically relevant hERG liability; ChEMBL puts its hERG IC50 around 30 micromolar, roughly a thousandfold above its H1 affinity.
- Abrupt discontinuation after months to years of daily use can trigger severe rebound pruritus, a phenomenon now recognised in the literature and reflected in recent labelling attention [7].
Mechanism
It is a carboxylated of hydroxyzine that acts as an inverse at peripheral H1 receptors and enters the brain far less than its parent does. It still sedates a minority of people, which is the usual reason someone switches to fexofenadine or bilastine.
receptor fingerprint
reading the marksactivatesblocks / inhibitsmodulates
01
H1 receptor (HRH1)Inverse agonist / antagonist; cetirizine is the racemate and levocetirizine is the active eutomer
strong
Relief of -mediated itch, sneeze, rhinorrhoea and weal-and-flare in rhinitis and urticaria
02
P-glycoprotein (ABCB1) at the Substrate, but a weaker one than fexofenadine or bilastine
moderate
Limits but does not abolish entry, which is why cetirizine is 'low-sedating' rather than genuinely non-sedating and does cause somnolence in a minority at 10 mg
03
hERG potassium channel (KCNH2)Very weak block; no clinically relevant QT effect
weakIC50 median 30,200 nM, roughly a thousandfold above H1 affinity
The wide margin is why cetirizine survived the antihistamine cardiotoxicity purge that removed terfenadine and astemizole
04
Eosinophil chemotaxis and adhesion-molecule (ICAM-1) expressionInhibited at clinically achievable concentrations
downstream
The anti-inflammatory effect beyond simple H1 blockade, long argued to underlie its performance in chronic urticaria
Safetyrisks and cautions, not medical advice
Cetirizine is a single molecule in the antihistamine class. A full adverse effect profile has not been compiled for this entry yet, so nothing here should be read as evidence that it is well tolerated; the absence is missing work rather than a finding. What is documented is what the compound is and what it is used for.
Where to buy
Suppliers
Vendors carrying Cetirizine, with live product details and codes. Links are affiliate links that support the wiki at no cost to you.
RUPharma🌐
Cetirizine
From$3
Options$3 to $20
ShipsWorldwide from Russia and India; 3 to 4 weeks to the US and Canada, and 4 to 7 days on the lines that ship express from India, Singapore or China. Europe and Asia are select destinations rather than every country
RUPharma🌐
Cetirizine
From$11
Options$11 to $31
ShipsWorldwide from Russia and India; 3 to 4 weeks to the US and Canada, and 4 to 7 days on the lines that ship express from India, Singapore or China. Europe and Asia are select destinations rather than every country
RUPharma🌐
Cetirizine
From$11
Options$11 to $38
ShipsWorldwide from Russia and India; 3 to 4 weeks to the US and Canada, and 4 to 7 days on the lines that ship express from India, Singapore or China. Europe and Asia are select destinations rather than every country
RUPharma🌐
Cetirizine
From$11
Options$11 to $32
ShipsWorldwide from Russia and India; 3 to 4 weeks to the US and Canada, and 4 to 7 days on the lines that ship express from India, Singapore or China. Europe and Asia are select destinations rather than every country
RUPharma🌐
Cetirizine
From$11
Options$11 to $32
ShipsWorldwide from Russia and India; 3 to 4 weeks to the US and Canada, and 4 to 7 days on the lines that ship express from India, Singapore or China. Europe and Asia are select destinations rather than every country
Research
- 1993first citedCetirizine: a new, nonsedating antihistamine.
- 1998controlled trialAllergic factors associated with the development of asthma and the influence of cetirizine in a…
- 2026most recentRebound Pruritus and Urticaria After Discontinuation of Chronic Antihistamine Use-A Scoping Rev…
- 1.Allergic factors associated with the development of asthma and the influence of cetirizine in a double-blind, randomised, placebo-controlled trial: first results of ETAC. Early Treatment of the Atopic Child.
- 2.A double-blinded, randomized, placebo-controlled trial of cetirizine in preventing the onset of asthma in children with atopic dermatitis: 18 months' treatment and 18 months' posttreatment follow-up.
- 3.Long-term treatment with cetirizine of infants with atopic dermatitis: a multi-country, double-blind, randomized, placebo-controlled trial (the ETAC trial) over 18 months.
- 4.Clinical pharmacology of the H1-receptor antagonists cetirizine and loratadine in children.
- 5.Compared pharmacological characteristics in humans of racemic cetirizine and levocetirizine, two histamine H1-receptor antagonists.
- 6.Cetirizine: a new, nonsedating antihistamine.
- 7.Rebound Pruritus and Urticaria After Discontinuation of Chronic Antihistamine Use-A Scoping Review.
- 8.Cetirizine-induce cholestasis.
8 listed here; entry last updated August 2026
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Notes and cautions
- Cetirizine has no boxed warning and is one of the safest widely used drugs, but two things are underappreciated.
- First, it is not truly non-sedating: somnolence occurs in roughly one in ten at 10 mg, the effect is dose-dependent and additive with alcohol and other CNS depressants, and it can impair driving in susceptible people.
- Second, stopping long-term daily use can cause severe rebound pruritus lasting days to weeks, which is frequently mistaken for a return of the original allergy and drives people back onto the drug indefinitely; tapering is the sensible approach after prolonged use [7].
- Dose reduction is required in renal impairment and in the elderly because clearance is predominantly renal.
- Rare hepatic injury including cholestasis has been reported [8], and dystonic or oculogyric reactions occur very rarely in children.
reading fda reports