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 antichloinergic 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 hydrochloride.
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) |
General disorders and administration site conditions Fatigue | 1.63% | 0.95% |
Nervous system disorders Dizziness 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, thoracic and mediastinaldisorders 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 event (WHO-ART) | Cetirizine 10 mg (n=1656) | Placebo (n=1294) |
Gastro-intestinal system disorders Diarrhoea | 1.0% | 0.6% |
Psychiatric disorders Somnolence | 1.8% | 1.4% |
Respiratory thoracic and mediastinal disorders Rhinitis | 1.4% | 1.1% |
General disorders and administration site conditions Fatigue | 1.0% | 0.3% |
The adverse effects listed below are classified by system organ class and frequency according to the following convention: 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) or very rare (<1/10,000).
MEDRA SOC | Adverse reaction | Frequency |
Blood and lymphatic disorders | Thrombocytopenia | Very rare |
Metabolism and nutrition disorders: | Increased appetite | Not known |
Psychiatric disorders: | Agitation | Uncommon: |
Aggression, confusion, depression, hallucinations, insomnia | Rare |
Tic | Very rare |
Suicidal ideation, nightmare | Not known |
Nervous system disorders: | Paraesthesia | Uncommon |
Convulsions, movement disorders | Rare |
Dysgeusia, syncope, tremor, dystonia, dyskinesia | Very rare |
Amnesia, memory impairment | Unknown |
Eye disorders | Accommodation disorder, blurred vision, oculogyration | Very rare |
Ear and labyrinth disorders | Vertigo | Not known |
Cardiac disorders | Tachycardia | Rare |
Gastro-intestinal disorders | Diarrhoea | Uncommon |
Hepatobiliary disorders: | Hepatic function abnormal (increased transaminases, alkaline phosphates, γ -GT and bilirubin) | Rare |
Hepatitis | Unknown |
Skin and subcutaneous tissue disorders | Pruritus, rash | Uncommon |
Urticaria | Rare |
Angioneurotic oedema, fixed drug eruption | Very rare |
Acute generalized exanthematous pustulosis (AGEP) | Unknown |
Musculoskeletal and connective tissue disorder | Arthralgia | Not known |
Renal and urinary disorders | Dysuria, enuresis | Very rare |
Urinary retention (see section Warnings and Precautions) | Not known |
General disorders and administration site conditions | Asthenia, malaise | Uncommon |
Oedema | Rare |
Investigations | Weight increased | Rare |
Immune system disorders | Hypersensitivity | Rare |
Anaphylactic shock | Very rare |
Skin reactions occuring after discontinuation of cetirizine
After discontinuation of cetirizine, pruritus (intense itching) and/or urticaria have been reported (see Section Warnings and Precautions).
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at:www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
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