| Undesirable effects are mainly related to CNS depressant or paradoxical CNS stimulation effects, to anticholinergic activity, or to hypersensitivity reactions. A Clinical trialsThe following table list the relevant undesirable effects reported in placebo-controlled clinical trials for hydroxyzine and including 735 subjects exposed to hydroxyzine up to 50 mg daily. The frequency has been estimated using the following definitions: very common ( 1/10); common ( 1/100 to < 1/10); uncommon ( 1/1000 to <1/100); rare ( 1/10000 to <1/1000); very rare (<1/10000), not known (cannot be estimated from the available data).System Organ Class | Adverse event preferred term | Frequency | Nervous system disorders | Somnolence | Very common | Headache | Common | Dizziness | Uncommon | Insomnia | Uncommon | Disturbance in attention | Uncommon | Gastrointestinal disorders | Dry mouth | Common | Constipation | Uncommon | Nausea | Uncommon | General disorders and administration site conditions | Fatigue | Common | Asthenia | Uncommon | B Post-marketing experienceThe following table lists, per body system, the additional undesirable adverse reactions reported during marketed use of the drug. No frequency can be estimated from post-marketing reporting of events.Immune system disorders : Hypersensitivity, anaphylactic shockPsychiatric disorders :Agitation, confusion, disorientation, hallucinationNervous system disorders : Sedation, tremor, convulsions, dyskinesia Eye disorders : Accommodation disorder, vision blurredCardiac disorders : Tachycardia Vascular disorders : Hypotension Respiratory, thoracic and mediastinal disorders : Bronchospasm Gastrointestinal disorders : Vomiting Skin and subcutaneous tissue disorders : Pruritus, erythematous rash, maculo-papular rash, urticaria, dermatitis, angioneurotic oedema, sweating increased, fixed drug eruptionRenal and urinary disorders : Urinary retentionGeneral disorders and administration site conditions : Malaise, pyrexiaInvestigations : Liver function tests abnormal | |