Consumer medicine information

Zilarex Tablets

Cetirizine hydrochloride


Brand name

Zilarex Tablets

Active ingredient

Cetirizine hydrochloride




Consumer medicine information (CMI) leaflet

Please read this leaflet carefully before you start using Zilarex Tablets.


This leaflet answers some common questions about Zilarex. It does not contain all the available information. It does not take the place of talking to your doctor or pharmacist.

All medicines have risks and benefits. Your doctor has weighed the risk of you taking Zilarex against the benefits it is expected to have for you.

If you have any concerns about taking this medicine, ask your doctor or pharmacist.

Keep this leaflet with the medicine.

You may want to read it again.


The name of your medicine is Zilarex. It contains the active ingredient cetirizine hydrochloride.

Cetirizine hydrochloride is an antihistamine used to relieve the symptoms of hayfever (also known as seasonal allergic rhinitis) and perennial allergic rhinitis e.g. sneezing, an itchy or runny nose and itchy, watering or red eyes. It is also used to treat some itchy skin rashes such as hives (also known as chronic idiopathic urticaria).

Ask your doctor if you have any questions about why Zilarex was prescribed for you.

Your doctor may have prescribed Zilarex for another reason.

There is no evidence that Zilarex is addictive.


When you must not take it

Do not take this medicine if you have an allergy to:

  • cetirizine hydrochloride, the active ingredient, or to any of the other ingredients listed at the end of this leaflet under Product Description
  • any other similar medicines such as hydroxyzine (another antihistamine, related to cetirizine)

Some of the symptoms of an allergic reaction may include:

  • shortness of breath
  • wheezing or difficulty breathing
  • swelling of the face, lips, tongue or other parts of the body
  • rash, itching or hives on the skin

Do not take this medicine if you have or have had severely impaired kidney function.

Do not take this medicine if you are pregnant.

It may affect your developing baby if you take it during pregnancy.

Do not breastfeed if you are taking this medicine.

The active ingredient in Zilarex passes into breast milk and there is a possibility that your baby may be affected.

Do not take this medicine after the expiry date printed on the pack or if the packaging is torn or shows signs of tampering.

If it has expired or is damaged, return it to your pharmacist for disposal.

If you are not sure whether you should start taking this medicine, talk to your doctor or pharmacist.

Before you start to take it

Tell your doctor or pharmacist if you have allergies to any other medicines, foods, preservatives or dyes.

Tell your doctor or pharmacist if you are pregnant or intend to become pregnant.

Like most medicines, Zilarex is not recommended for use during pregnancy. If there is a need to consider Zilarex during your pregnancy, your doctor or pharmacist will discuss with you the benefits and risks of using it.

Tell your doctor or pharmacist if you are breastfeeding or plan to breastfeed.

Your doctor or pharmacist will discuss the possible risks and benefits of using Zilarex during breastfeeding.

Tell your doctor or pharmacist if you have or have had any medical conditions, especially the following:

  • epilepsy (fits/seizures/convulsions)
  • kidney problems.

Zilarex contains lactose.

If you have been told by your doctor that you have intolerance to some sugars, tell your doctor or pharmacist before taking it.

If you have not told your doctor or pharmacist about any of the above, tell him/her before you start taking Zilarex.

Taking other medicines

Tell your doctor or pharmacist if you are taking any other medicine, including any that you buy without a prescription from your pharmacy, supermarket or health food shop.

Some medicines may be affected by Zilarex or may affect how well it works. Your doctor or pharmacist can advise you about other medicines you might need to be careful with, while taking Zilarex.


Follow all directions given to you by your doctor or pharmacist carefully.

They may differ from the information contained in this leaflet.

If you do not understand the instructions, ask your doctor or pharmacist for help.

How much to take

The usual dose for adults and children 12 years and over is one tablet daily. Some adults may require only half a tablet per day (e.g. people with kidney problems). Some adults may require the maximum dose of two tablets (20mg) per day.

The usual dose for children 6-12 years of age is half a tablet twice a day. Zilarex is not recommended for children under 6 years of age.

Ask your doctor or pharmacist if you are unsure of the correct dose for you.

They will tell you exactly how much to take.

Follow the instructions they give you.

If you take the wrong dose, Zilarex may not work as well and your problem may not improve.

How to take it

The tablets should be swallowed with a glass of water. They can be taken with or without food.

If you need to break the Zilarex tablet, hold tablet with both hands and snap along break line.

When to take Zilarex

If this medicine makes you feel drowsy, take the tablet in the evening or at bed time.

Take your medicine at about the same time each day.

Taking it at the same time each day will have the best effect. It will also help you remember when to take it.

Zilarex can be taken when allergic symptoms start showing:

  • hayfever may begin with itchiness in the throat, nose or eyes
  • hives will usually cause your skin to itch and you may notice pink lumps appearing.

People suffering from hayfever will usually need to take Zilarex during spring and summer, when there is more pollen in the air to trigger symptoms.

How long to take Zilarex

You can stop taking Zilarex when you obtain relief from your symptoms. It can be restarted if your symptoms recur.

If your condition does not improve after a few days or it is not well controlled by Zilarex, speak to your doctor or pharmacist.

If you forget to take it

If you (or a child 12 years or over) forget to take a dose, take one dose as soon as you remember, but wait at least 12 hours before taking the next dose. If you forget to give your child (6-12 years) their dose, give them one dose as soon as you remember, but wait at least 6 hours before giving the next dose to your child.

Do not take a double dose to make up for the dose that you missed.

This may increase the chance of getting an unwanted side effect.

If you are not sure what to do, ask your doctor or pharmacist.

If you have trouble remembering to take your medicine, ask your pharmacist for some hints.

If you take too much

Immediately telephone your doctor or the Poisons Information Centre (telephone Australia 13 11 26 or New Zealand 0800 POISON or 0800 764 766) or go to Accident and Emergency at your nearest hospital, if you think that you or anyone else has taken too much Zilarex. Do this even if there are no signs of discomfort or poisoning.

You may need urgent medical attention.

If you take too much Zilarex, you may feel confused, drowsy, dizzy, restless, tired and may experience diarrhoea, headaches, rash, a rapid heart rate and tremors.


Things you must do

If you are about to be started on any new medicine, remind your doctor and pharmacist that you are taking Zilarex.

Tell any other doctors, dentists and pharmacists who treat you that you are taking this medicine.

If you are going to have surgery, tell the surgeon or anaesthetist that you are taking this medicine.

It may affect other medicines used during surgery.

If you become pregnant while taking this medicine, tell your doctor immediately.

Do not take this medicine for 3 days before any allergy tests.

This medicine will interfere with the results of an allergy test.

If you already know which substances set off your allergies, keep a supply of Zilarex tablets ready so you know you can control the symptoms when they start appearing.

Things you must not do

Do not take Zilarex to treat any other complaints unless your doctor tells you to.

Do not give your medicine to anyone else, even if they have the same condition as you.

Things to be careful of

Be careful driving or operating machinery until you know how Zilarex affects you.

Zilarex may cause dizziness, light-headedness, tiredness or drowsiness in some people. Make sure you know how you react to Zilarex before you drive a car, operate machinery, or do anything else that could be dangerous if you are dizzy or light-headed. If this occurs do not drive. If affected, children should be careful when riding bicycles or climbing trees.

Be careful when drinking alcohol while you are taking this medicine.

If you drink alcohol, dizziness, light-headedness, drowsiness, alertness and motor performance may be worse.

Try to avoid contact with known substances you are allergic to.

Hives are sometimes caused by allergy to certain foods; you should talk to your doctor for more information or if you are worried about this.


Tell your doctor or pharmacist as soon as possible if you do not feel well while you are taking Zilarex.

All medicines can have unwanted effects. Sometimes they are serious, most of the time they are not. You may need medical attention if you get some of the side effects.

Do not be alarmed by this list of possible side effects. You may not experience any of them.

Ask your doctor or pharmacist to answer any questions you may have.

Tell your doctor or pharmacist if you notice any of the following and they worry you:

  • drowsiness, sleepiness, fatigue
  • dizziness or lightheadedness
  • dry mouth
  • headache
  • stomach upset e.g. changes in bowel habits, diarrhoea, nausea and vomiting
  • a restless or agitated feeling
  • rash
  • difficulty breathing/shortness of breath and wheezing
  • rapid heart rate
  • loss of or increase appetite
  • unintentional weight change
  • generally feeling ill.

These side effects are usually mild and short-lived.

Tell your doctor or pharmacist if you notice anything that is making you feel unwell.

Other side effects not listed above may occur in some patients.



Keep Zilarex in the original packaging until you need to take it.

If you take it out of its original container it may not keep well.

Keep your medicine in a cool dry place where the temperature stays below 25°C.

Do not store Zilarex or any other medicine in the bathroom or near a sink. Do not leave it on a window sill or in the car.

Heat and dampness can destroy some medicines.

Keep it where children cannot reach it.

A locked cupboard at least one-and-a-half metres above the ground is a good place to store medicines.


If your doctor tells you to stop taking this medicine or the expiry date has passed, ask your pharmacist what to do with any medicine that is left over.


What it looks like

Zilarex 10 mg: white, oblong-shaped tablets with a score notch on one side. Available in blister packs of 10 or 30 tablets.


Active ingredient:

  • Zilarex 10 mg - 10mg cetirizine hydrochloride.

Inactive ingredients:

  • lactose
  • cellulose microcrystalline
  • silica colloidal anhydrous
  • magnesium stearate
  • hypromellose
  • titanium dioxide
  • macrogol 4000.

This medicine does not contain sucrose, gluten, tartrazine or any other azo dyes.


Sandoz Pty Ltd
ABN 60 075 449 553
19 Harris St
Pyrmont NSW 2009
Tel: 1800 634 500

Novartis New Zealand Ltd
Private Bag 65904 Mairangi Bay
Auckland 0754
New Zealand
Tel: 0800 354 335

This leaflet was revised in August 2011.

Australian registration number:

Zilarex 10 mg tablets:
AUST R 120710 (blisters)


Brand name

Zilarex Tablets

Active ingredient

Cetirizine hydrochloride




Name of the medicine

Cetirizine hydrochloride.


Lactose, cellulose microcrystalline, silica colloidal anhydrous, magnesium stearate, hypromellose, titanium dioxide, macrogol 4000.


The chemical name of cetirizine hydrochloride is 2-(2- (4-(4-chlorophenyl) phenylmethyl)-1-piperazinyl) ethoxy) acetic acid, dihydrochloride. The molecular weight is 461.8.
Cetirizine hydrochloride is a white, crystalline powder and is water soluble (160 g/100 mL).
It is formulated as white, film-coated, scored tablets. Each tablet contains 10 mg cetirizine hydrochloride. Zilarex tablets also contain lactose, cellulose microcrystalline, silica colloidal anhydrous, magnesium stearate, hypromellose, titanium dioxide, macrogol 4000.


Cetirizine hydrochloride is an orally active H1-receptor antagonist.

Mechanism of action.

Cetirizine, a human metabolite of hydroxyzine, is an antiallergic compound; its principal effects are mediated via competitive occupancy of peripheral H1-receptors. Cetirizine is distinguished from other antihistamines by the presence of a carboxylic acid function. This difference may be partly responsible for the selectivity of cetirizine seen in pharmacological models and its distinctive pharmacokinetic properties in man. Thus, while the activity of cetirizine as an antihistamine is comparable to other agents, in vivo animal models have shown negligible anticholinergic or antiserotoninergic activity.
In vitro receptor binding studies have shown no measurable affinity for receptors other than H1-receptors.

CNS Effects.

Autoradiographic studies with radiolabelled cetirizine in the rat have shown very low penetration of the brain. Sedation was observed in animal studies, but only at doses at least 1,000 times greater than those required for antagonism of histamine H1-receptors. Studies in normal volunteers using objective measurements have, most of the time, shown no effect of cetirizine at the recommended dosage of 10 mg on sleep latency time, cognitive function or motor performance. However, the occurrence of CNS effects have been observed in clinical trials in some patients (see Adverse Effects).
Studies using quantitative EEG recordings and various other tests of cognitive function confirmed that cetirizine does not cause CNS depression.


Studies in normal volunteers show that cetirizine at doses of 5 to 20 mg strongly inhibits the skin wheal and flare caused by the intradermal injection of histamine. The onset of activity corresponds with the occurrence of maximal plasma levels, and significantly blockade persists for at least 24 hours after a single dose. The effects of intradermal injection of various other mediators or histamine releasers are also inhibited by cetirizine, as is cold-induced urticaria. The late phase recruitment of eosinophils, a component of the allergic inflammatory response, is inhibited by cetirizine following cutaneous antigen challenge.


Cetirizine is rapidly absorbed after oral administration. In adults, peak plasma levels after a 10 mg dose are approximately 350 nanogram/mL and occur at about one hour. Co-administration with food slows absorption (lower Cmax and greater Tmax), but does not affect bioavailability as measured by the AUC. Plasma protein binding is 93%. The apparent volume of distribution is 0.45 L/kg, suggestive of significant extravascular distribution. The plasma elimination half-life in adults is approximately 8 hours and does not change with multiple dosing. Plasma levels are proportional to the dose administered over the recommended range of 5 to 20 mg.
In children, as with adults, cetirizine is eliminated mostly in the urine. Children over 6 years of age show peak plasma levels and times to peak similar to adults, with slightly more rapid elimination. Younger children have more rapid clearance and a shorter half-life relative to adults. The half-life of cetirizine is approximately 7 hours in children aged 6 to 12 years, 5 hours in children aged 2 to 6 years and 3 hours in infants and toddlers aged 6 to 24 months.
In contrast to other known antihistamines, cetirizine is less extensively metabolised, and approximately 60% of an administered dose is excreted unchanged in the urine. This results in high bioavailability with low inter- or intrasubject variation in blood levels. A study using 14C-labelled cetirizine showed that most of the plasma radioactivity is associated with the parent compound. Only one metabolite has been identified in human plasma, the product of oxidative dealkylation of the terminal carboxymethyl group. The antihistaminic activity of this metabolite is negligible.
The total body clearance of cetirizine is reduced in subjects with renal dysfunction but below a creatinine clearance of about 30 to 50 mL/minute, little further change occurs. Plasma levels of cetirizine are essentially unaffected by haemodialysis, and the plasma elimination half-life in dialysis patients is approximately 20 hours. The plasma AUC is increased about threefold in these patients. The clearance of cetirizine is reduced in elderly patients, but only in proportion to the decrease in creatinine clearance. Thus, in 16 patients with a mean age of 77 years, half-life increased to 12 hours. Cetirizine blood levels were monitored in a clinical trial of 59 patients, aged 60 to 82, who received 10 mg of cetirizine daily for three weeks, and no undue accumulation of cetirizine was found.


Seasonal allergic rhinitis.

Cetirizine is indicated for the relief of symptoms associated with seasonal allergic rhinitis (hay fever) in adults and children aged 6 years and over. Symptoms treated effectively include sneezing, rhinorrhoea, post-nasal discharge, nasal pruritus, ocular pruritus and tearing and redness of the eyes.

Perennial allergic rhinitis.

Cetirizine is indicated for the relief of symptoms associated with perennial allergic rhinitis in adults and children aged 6 years and over. Symptoms treated effectively include sneezing, rhinorrhoea, post-nasal discharge, nasal pruritus, ocular pruritus and tearing.

Chronic idiopathic urticaria.

Cetirizine is indicated for the treatment of the uncomplicated skin manifestations of chronic idiopathic urticaria in adults and children aged 6 years and over. It significantly reduces the occurrence, severity and duration of hives and markedly reduces pruritus. As with other antihistamines, patients should be advised to seek medical advice about the possibility that their urticaria is associated with ingestion of certain foods.


Cetirizine hydrochloride is contraindicated in those patients with a known hypersensitivity to it, or to its parent compound, hydroxyzine, or to any piperazine derivatives or to any other of the ingredients of Zilarex.
Zilarex is also contraindicated in patients with severe renal impairment (less than 10 mL/min creatinine clearance).


Activities requiring mental alertness.

Some patients may experience a degree of drowsiness with cetirizine. Studies using objective measurements have shown no effect of cetirizine on cognitive function, motor performance or sleep latency. However, in clinical trials, the occurrence of CNS effects has been observed in some individual patients and due caution should be exercised when driving a car or operating potentially dangerous machinery. In sensitive patients, concurrent use with alcohol or other CNS depressants may cause additional reductions in alertness and impairment of performance.


Although it has been shown that cetirizine at the recommended dose of 10 mg does not potentiate the effect of alcohol, in sensitive patients, the simultaneous administration of cetirizine and alcohol or other CNS depressants may have affects in the CNS. Therefore, precaution is recommended if alcohol is taken concomitantly.

Patients with epilepsy.

CNS stimulation may occur with antihistamines, especially in children. Therefore, caution is recommended when treating patients suffering from epilepsy or patients at risk of convulsions.

Carcinogenesis and mutagenesis.

Carcinogenicity studies over 24 months showed increased incidences of benign liver tumours in male mice (at the maximum dose of 16 mg/kg/day), but not in female mice or in rats. These benign tumours in mice are commonly found with compounds which cause liver enzyme induction. Since cetirizine does not induce liver enzymes in non-rodents and humans, this may be considered to be a species specific phenomenon. Cetirizine was devoid of mutagenic activity in a series of in vitro and in vivo assays.

Use in pregnancy.

(Category B2)
Reproduction studies in mice, rats and rabbits failed to show evidence of teratogenicity using doses up to 96, 225, and up to 135 mg/kg/day respectively. However, the short half-life of cetirizine in these species suggests that foetal exposure may have been inadequate. In mice, post-natal development was inhibited after 96 mg/kg/day. Clinical data for cetirizine or other compounds of the class are inadequate to establish safety in pregnancy. Until such data are available, cetirizine should be used in pregnancy only if the expected benefits clearly outweigh potential risks to mother and foetus.
Australian categorisation definition of Category B2: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human foetus having been observed.
Studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of foetal damage.

Use in lactation.

Studies in beagle dogs indicate that approximately 3% of the dose is excreted in milk. Cetirizine is excreted in human milk at concentrations representing 0.25 to 0.90 those measured in plasma, depending on sampling time after administration. Use of cetirizine in breastfeeding mothers should be avoided.

Paediatric use.

Cetirizine is not recommended for use in children under 12 months of age. The use of the tablets is not recommended in children aged less than 6 years since this formulation does not allow for appropriate dose adaptation.

Use in the elderly.

Cetirizine is well tolerated by patients 65 years of age and over. Clearance of cetirizine is reduced in proportion to creatinine clearance. In patients whose creatinine clearance is reduced (i.e. those with moderate renal impairment), a starting dose of 5 mg/day is recommended.

Patients with renal insufficiency.

Dosing adjustment is necessary in patients with renal insufficiency (see Dosage and Administration).

Patients with hepatic insufficiency.

Dosing adjustment may be necessary in patients with hepatic insufficiency (See Dosage and Administration).


Cetirizine contains lactose. It should not be given to patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption.

Effects on laboratory tests.

Allergy skin tests are inhibited by antihistamines and a wash-out period (of 3 days) is required before performing them.


Studies with cetirizine demonstrated that there were no clinically relevant adverse interactions with pseudoephedrine, cimetidine, ketoconazole, erythromycin, azithromycin, glipizide and diazepam. A small decrease in the clearance of cetirizine (16%) was observed in a multiple dose study with theophylline (400 mg once a day), while the disposition of theophylline was not altered by concomitant cetirizine administration. In a multiple dose study of ritonavir (600 mg twice daily) and cetirizine (10 mg daily), the extent of exposure to cetirizine was increased by about 40% while the disposition of ritonavir slightly altered (-11%) further to concomitant cetirizine administration.

Adverse Effects

The more commonly observed untoward events reported during cetirizine administration and not associated with an equivalent incidence among placebo-treated patients are somnolence, dry mouth and fatigue.
Table 1 shows adverse events occurring with an incidence of greater than 1% after intake of cetirizine 5 to 20 mg cetirizine a day. It pools all the American and European clinical studies (including open studies with access to rescue drug) in urticaria, perennial and seasonal rhinitis. The incidence of somnolence associated with cetirizine was 14.3% (7.6% under placebo) and was predominantly mild to moderate in severity. After pooling the same studies in the three registered indications, sedation is reported more in the patients suffering from seasonal allergic rhinitis, than in the patients suffering from perennial allergic rhinitis and urticaria.
Assessment of severity of sedation in clinical trials indicates the mild nature of sedation associated with cetirizine.
The following events were observed infrequently (less than 1/100), but more than once, in 2,487 patients who received cetirizine in all US and European trials; a causal relationship with cetirizine administration has not been established. Events are listed in order of decreasing frequency within a given body system.

Autonomic nervous system.

Increased appetite, anorexia, flushing, increased sweating.




Earache, epistaxis, altered sense of taste, tinnitus, tongue disorder.


Eye abnormality, periorbital oedema, abnormal vision, eye pain, conjunctivitis.


Abdominal pain, diarrhoea, vomiting, constipation, flatulence.


Polyuria, urinary retention, urinary tract infection.


Back pain, myalgia, arthralgia, bone disorder (fracture), leg cramps.


Nervousness, impaired concentration, confusion, paraesthesia, asthenia, hypertonia, tremor.

Respiratory system.

Respiratory disorder, coughing, bronchospasm, upper respiratory tract infection, dyspnoea.


Weight increase (see comment below), fever, oedema, chest pain, pain, rigors, dysmenorrhoea, thirst, decreased libido.
Weight gain was reported as an adverse effect in 0.4% of cetirizine patients in placebo-controlled trials. In an open study of six months' duration, the mean gain in weight was 2.8% after 20 weeks, with no further increase at 26 weeks. This effect has been reported for other antihistamines.
Occasional instances of reversible liver function test (transaminase) elevations have occurred during cetirizine therapy, without evidence of jaundice or other clinical findings.
Adverse events at rates of 1% or greater in children aged from 6 months to 12 years, included in placebo-controlled trials are in Table 2.

Postmarketing experience.

In addition to the adverse events reported during clinical studies and listed above, the following undesirable effects have been reported in postmarketing experience.
Undesirable effects are described according to MedDRA System Organ Class and by estimated frequency based on postmarketing experience.
Experiences are defined as follows: Very common (≥ 1/10), common (≥ 1/100 to < 1/10), uncommon (≥ 1/1,000 to < 1/100), rare (≥ 1/10.000 to < 1/1,000), very rare (< 1/10,000).

Blood and lymphatic system disorders.

Very rare: thrombocytopenia.

Immune system disorders.

Rare: hypersensitivity.
Very rare: anaphylactic shock.

Psychiatric disorders.

Uncommon: agitation.
Rare: aggression, confusion, depression, hallucination, insomnia.
Very rare: tics.

Nervous system disorders.

Rare: convulsions.
Very rare: syncope, dysgeusia, dyskinesia, dystonia.

Eye disorders.

Very rare: accommodation disorder; blurred vision; oculogyration.

Hepatobiliary disorders.

Rare: abnormal hepatic function (increased transaminases, alkaline phosphatase, gamma-GT and bilirubin).

Skin and subcutaneous tissue disorders.

Uncommon: pruritis, rash.
Rare: urticaria.
Very rare: angioneurotic oedema, fixed drug eruption.

Renal and urinary disorders.

Very rare: dysuria, enuresis.

General disorders and administration site conditions.

Uncommon: malaise.


Stillbirth, glomerulonephritis, cholestasis, haemolytic anaemia, hepatitis and severe hypotension. Data are insufficient to support an estimate of their incidence in the population to be treated.

Dosage and Administration

Paediatric use.

6-12 years of age.

The recommended daily dose is 10 mg, given as 5 mg twice daily with or without food.

Adults and children 12 years and over.

The recommended initial dose of cetirizine is 10 mg, given as a single dose, with or without food. The time of administration may be varied to suit individual patient needs. If sufficient response is not obtained, the dose may be increased as necessary to the maximum recommended daily dose of 20 mg.

Use in the elderly.

There are no data to suggest that elderly who have normal renal function require a lower dose. However, as advancing age may be associated with declining renal function, dosage may need to be reduced in the elderly if creatinine clearance is reduced.

Renal insufficiency.

Cetirizine clearance is reduced in patients with renal impairment. In patients with renal insufficiency, dosage should be reduced to half the usual recommended dose. Zilarex is contraindicated in patients with severe renal impairment (less than 10 mL/min creatinine clearance (see Contraindications).

Hepatic insufficiency.

In patients with hepatic insufficiency, a dose of 5 mg once daily is recommended. In paediatric patients aged 6 to 11 years, with impaired hepatic function a dose of 5 mg once daily is recommended.


Symptoms observed after an overdose of cetirizine are mainly associated with CNS effects that could suggest an anticholinergic effect. Adverse events reported after an intake of at least 5 times the recommended daily dose are confusion, diarrhoea, dizziness, fatigue, headache, malaise, mydriasis, pruritis, restlessness, sedation, somnolence, stupor, tachycardia, tremor and urinary retention.
Should overdose occur, treatment should be symptomatic or supportive, taking into account any concomitantly ingested medications. There is no known specific antidote to cetirizine. Cetirizine is not effectively removed by dialysis, and dialysis will be ineffective unless an agent which is removed by dialysis has been concomitantly ingested.
In case of overdose, the Poisons Information Centre (telephone 131 126) should be contacted immediately.


Zilarex tablets are white, film-coated, oblong tablets, scored on one face. They are available in blister packs of 10 and 30 tablets.

Poison Schedule