ZIRTEC ® - Cetirizine

ZIRTEC ® is a drug based on Cetirizine dihydrochloride

THERAPEUTIC GROUP: Antihistamines for systemic use - H1 antagonist

Indications ZIRTEC ® - Cetirizine

ZIRTEC ® is indicated in the symptomatic treatment of allergic states and in particular in the treatment of rhinitis and allergic conjunctivitis and chronic idiopathic urticaria.

Mechanism of action ZIRTEC ® - Cetirizine

ZIRTEC ® is a drug based on Cetirizine, a piperazine derivative counted among the second generation H1 antagonists, and therefore characterized by pharmacokinetic and pharmacodynamic properties such as to optimize the interaction with the H1 receptors, thus limiting the onset of central side effects such as sedation.
Like the other antihistamines antagonists of the H1 receptors, even Cetirizine, albeit with greater affinity, following a good intestinal absorption, reaches these receptors, disseminated among the various organs and systems, limiting their activation and thus manifesting:

  • An anti-edema action, controlling vascular permeability at the level of the perivenular capillaries;
  • An anti-bronchospasmic action, controlling the activation of histamine receptors at the level of smooth muscle, precisely responsible for bronchospasm.

Once its activity is over and without an intense hepatic metabolism, Cetirizine, still in unchanged form, is eliminated mainly through the urine.

Studies carried out and clinical efficacy

Br J Pharmacol. 2010 Sep; 161: 456-66.

Histamine H1 receptor antagonist cetirizine impairs working memory processing speed, but not episodic memory.

van Ruitenbeek P, Vermeeren A, Riedel WJ.

In light of the numerous evidences that describe the importance of the histaminergic pattern in the control of nervous functions, and in particular of cognitive functions, this study demonstrates how Cetirizine can reduce cognitive performance, however in a not serious way and without defining side effects. significant.

Nagoya J Med Sci. 2008 Aug; 70 (3-4): 97-106.

Evaluation of cetirizine hydrochloride-based therapeutic strategy for chronic urticaria.

Sugiura K, Hirai S, Suzuki T, Usuda T, Kondo T, Azumi T, Masaki S, Yokoi T, Nitta Y, Kamiya S, Ando K, Mori T, Tomita Y.

Study that demonstrates how treatment with Cetirizine at 10 mg daily for two weeks can guarantee in the first instance a remission of symptoms related to chronic idiopathic urticaria in about 74% of treated patients, reaching 83% after another 2 weeks.

J Am Acad Dermatol. 2004 Jun; 50: 953-6.

Cutaneous drug eruption from cetirizine and hydroxyzine.

Lew BL, Haw CR, Lee MH.

Interesting case report that reports the onset of adverse skin reactions following the use of Cetirizine, demonstrating a potential cross-reactivity between this active ingredient and other functionally related ones.

Method of use and dosage

10 mg coated tablets of Cetirizine dihydrochloride;
10 mg oral drops of Cetirizine dihydrochloride per ml of solution.
Dosage and timing of intake should be defined by your doctor based on the age of the patient, his general health conditions and the severity of the clinical picture in progress.
Considering the dose of 10 mg per day of Cetirizine, as the most used and effective in adults, in certain cases the doctor could consider the idea of ‚Äč‚Äčadapting the dosages by formulating doses that respect the degree of renal function of the patient.
Same thing is said for pediatric patients.

Warnings ZIRTEC ® - Cetirizine

The intake of ZIRTEC ® must be preceded by a careful medical examination necessary to verify the patient's overall state of health, as well as the specific symptoms, in order to identify conditions incompatible with antihistamine therapy.
Particular caution should in fact be reserved for all patients suffering from hepatic, renal, cardiac and neurological diseases, potentially more exposed to the onset of the side effects of Cetirizine.
It is also useful to remember how the presence of hydroxybenzoates in the formulation in oral drops could determine the development of hypersensitivity reactions in predisposed patients.
ZIRTEC ® in tablets contains lactose, therefore its intake is not recommended in patients with glucose-galactose malabsorption syndrome, lactase enzyme deficiency and hereditary galactose intolerance.
In order to obtain adequate results, it is recommended to stop taking antihistamines at least 48 hours before allergy tests.
Keep this medicine out of the reach of children.


The absence of clinical trials able to verify with absolute certainty the safety of Cetirizine for the health of the unborn child and the infant, require the utmost caution to the use of ZIRTEC ® during pregnancy and in the subsequent breastfeeding period.

The use of this drug, in the aforementioned periods, should be limited to cases of unavoidable necessity and always supervised by your gynecologist.


The patient treated with ZIRTEC ® should pay particular attention to the intake of alcohol and other active ingredients that can increase the risk of adverse reactions.

Contraindications ZIRTEC ® - Cetirizine

The use of ZIRTEC ® is contraindicated in case of hypersensitivity to the active ingredient or to one of its excipients or to other structurally related molecules and in patients with severe liver disease and kidney disease.

Undesirable Effects - Side Effects

Therapy with ZIRTEC ®, especially when prolonged for a long time or carried out in predisposed patients, could lead to the onset of diarrhea, hypertransaminasemia, asthenia, malaise, agitation and dermatological reactions due to hypersensitivity to the active ingredient or its excipients.
Fortunately rare are the neurological effects characterized by headache, sedation and drowsiness such as to make the driving of vehicles or the use of machinery dangerous.


ZIRTEC ® is a prescription drug.

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