| Clinical studies have shown that cetirizine at the recommended dosage has minor adverse effects on the CNS, including somnolence in children and adults, fatigue, dizziness and headache. In some cases, paradoxical CNS stimulation has been reported; mouth dryness, drowsiness, agitation, abdominal complaints and digestive disorders. Exceptionally, cases of allergic reactions such as cutaneous reactions and angioedema (Quincke's Oedema) have 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 drug.a) Clinical trialsDouble blind controlled clinical 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 reactions were reported for cetirizine 10 mg in the placebo-controlled trials at rates of 1.0 % or greater:| Adverse reactions(WHO-ART) | Cetirizine 10 mg(n= 3260) | Placebo(n = 3061) | | Body as a whole general disordersFatigue
| 1.63 %
| 0.95 %
| | Central and peripheral nervous system disordersDizziness
Headache | 1.10 %
7.42 %
| 0.98 %
8.07 %
| | Gastro-intestinal system disordersAbdominal pain
Dry mouth
Nausea | 0.98 %
2.09 %
1.07 %
| 1.08 %
0.82 %
1.14 %
| | Psychiatric disordersSomnolence
| 9.63 %
| 5.00 %
| | Respiratory system disordersPharyngitis
| 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 reactions at rates of 1 % or greater in children aged from 6 months to 12 years, included in placebo-controlled clinical trials are:| Adverse reactions(WHO-ART) | Cetirizine(n=1656) | Placebo(n =1294) | | Gastro-intestinal system disordersDiarrhoea
| 1.0 %
| 0.6 %
| | Psychiatric disordersSomnolence
| 1.8 %
| 1. 4 %
| | Respiratory system disordersRhinitis
| 1.4 %
| 1.1 %
| | Body as a whole general disordersFatigue
| 1.0 %
| 0.3 %
| b) Post-marketing experienceIn addition to the adverse reactions reported during clinical studies and listed above, the following undesirable effects 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: hypersensitivity Very rare: anaphylactic shock• Psychiatric disorders: Uncommon: agitation Rare: aggression, confusion, depression, hallucination, insomnia Very rare: tics• Nervous system disorders: Uncommon: paraesthesia Rare: convulsions Very rare: dysgeusia, dyskinesia, dystonia, syncope, tremor Not known: amnesia, memory impairment• Eye disorders: Very rare: accommodation disorder, blurred vision, oculogyration• Cardiac disorders: Rare: tachycardia• Gastro-intestinal disorders: Uncommon: diarrhoea• Hepatobiliary disorders: Rare: hepatic function abnormal (increased transaminases, alkaline phosphatase, γ-GT and bilirubin)• Skin and subcutaneous tissue disorders: Uncommon: pruritus, 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: asthenia, malaise Rare: oedema• Investigations: Rare: weight increased | |