| Clinical studies have shown that cetirizine at the recommended dosage has minor undesirable effects on the CNS, including somnolence, fatigue, dizziness and headache. In some cases, paradoxical CNS stimulation has been reported.Although cetirizine is a selective antagonist of peripheral H1-receptors and is relatively free of anticholinergic activity, isolated cases of micturition difficulty, eye accommodation disorders and dry mouth have been reported.Instances of abnormal hepatic function with elevated hepatic enzymes accompanied by elevated bilirubin have been reported. Mostly this resolves upon discontinuation of the treatment with cetirizine dihydrochloride. Clinical trials Double blind controlled clinical or pharmacoclinical trials comparing cetirizine to placebo or other antihistamines at the recommended dosage (10 mg daily for cetirizine), of which quantified safety data are available, included more than 3200 subjects exposed to cetirizine.From this pooling, the following adverse events were reported for cetirizine 10 mg in the placebo-controlled trials at rates of 1.0 % or greater:| Adverse event (WHO-ART)
| Cetirizine 10 mg (n= 3260)
| Placebo (n = 3061)
| | Body as a whole general disorders Fatigue
| 1.63 %
| 0.95 %
| | Central and peripheral nervous system disordersDizziness Headache
| 1.10 %7.42 %
| 0.98 %8.07 %
| | Gastro-intestinal system disorders Abdominal pain Dry mouth Nausea
| 0.98 %2.09 %1.07 %
| 1.08 %0.82 %1.14 %
| | Psychiatric disorders Somnolence
| 9.63 %
| 5.00 %
| | Respiratory system disorders Pharyngitis
| 1.29 %
| 1.34 %
| Although statistically more common than under placebo, somnolence was mild to moderate in the majority of cases. Objective tests as demonstrated by other studies have demonstrated that usual daily activities are unaffected at the recommended daily dose in healthy young volunteers.Adverse drug reactions at rates of 1 % or greater in children aged from 6 months to 12 years, included in placebo-controlled clinical or pharmacoclinical trials are:| Adverse drug reactions (WHO-ART)
| Cetirizine (n= 1656)
| Placebo (n = 1294)
| | Gastro-intestinal system disorders Diarrhoea
| 1.0 %
| 0.6 %
| | Psychiatric disorders Somnolence
| 1.8 %
| 1. 4 %
| | Respiratory system disorders Rhinitis
| 1.4 %
| 1.1 %
| | Body as a whole general disorders Fatigue
| 1.0 %
| 0.3 %
|
Post-marketing experience In addition to the adverse effects reported during clinical studies and listed above, isolated cases of the following adverse drug reactions have been reported in post-marketing experience. Undesirable effects are described according to MedDRA System Organ Class and by estimated frequency based on post-marketing experience.Frequencies 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), not known (cannot be estimated from the available data)• Blood and lymphatic disorders: Very rare: thrombocytopenia• Immune system disorders: Rare: hypersensitivityVery rare: anaphylactic shock• Psychiatric disorders: Uncommon: agitationRare: aggression, confusion, depression, hallucinations, insomniaVery rare: tics• Nervous system disorders: Uncommon: paraesthesiaRare: convulsions, movement disordersVery rare: dysgeusia, syncope, tremor, dystonia, dyskinesiaNot known: amnesia, memory impairment• Eye disorders: Very rare: accommodation disorder, blurred vision, oculogyration• Cardiac disorders: Rare: tachycardia• Gastrointestinal disorders: Uncommon: diarrhoea• Hepatobiliary disorders: Rare: hepatic function abnormal (increased transaminases, alkaline phosphatase, γ-GT and bilirubin)• Skin and subcutaneous tissue disorders: Uncommon: pruritus, rashRare: urticariaVery rare: angioneurotic oedema, fixed drug eruption• Renal and urinary disorders: Very rare: dysuria, enuresis• General disorders and administration site conditions: Uncommon: asthenia, malaiseRare: oedema• Investigations: Rare: weight increased | |