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Antihistamine (H1) — Anxiolytic / Sedative Pregnancy: Contraindicated. Verbatim §4.6: 'Hydroxyzine Tablets should not be used during pregnancy (see section 4.3 'Contraindications'). Clinical data in humans are inadequate to establish safety in early pregnancy. The use of sedating antihistamines in the latter part of the third trimester may cause adverse effects in neonates such as irritability, paradoxical excitability, and tremor. Animal studies have shown reproductive toxicity... Hydroxyzine crosses the placental barrier which may lead to higher foetal than maternal concentrations. In neonates whose mothers received Hydroxyzine Tablets during late pregnancy and/or labour, the following events were observed immediately or only a few hours after birth: hypotonia, movement disorders including extrapyramidal disorders, clonic movements, CNS depression, neonatal hypoxic conditions, or urinary retention.' Breast-feeding, verbatim: 'It is expected that Hydroxyzine Tablets may be excreted into breast milk. The effects on the nursing infant are unknown. Hydroxyzine Tablets should not be given to nursing mothers (see section 4.3).' Fertility: 'No human data on the effect of hydroxyzine on fertility are available.'

Hydroxyzine

Brand names: Atarax, Ucerax

Hydroxyzine is a sedating first-generation antihistamine used for the short-term management of anxiety and for symptomatic relief of pruritus.

Adult dose

Dose: Anxiety: 50–100 mg daily in divided doses
Route: Oral
Frequency: Daily in divided doses
Max: Maximum daily dose 100 mg per day in adults; maximum daily dose 50 mg per day in the elderly
SCOPE — anxiety is this page's primary indication (Psychiatry; category 'Antihistamine (H1) — Anxiolytic / Sedative') and the oral route is the SPC's only route ('Method of administration: Oral'). Verbatim §4.2: 'Anxiety Adults 50-100mg daily in divided doses'. Adult ceiling, verbatim: 'In adults and children over 40 kg in weight, the maximum daily dose is 100mg per day.' Elderly, verbatim: 'In the elderly, the maximum daily dose is 50 mg per day (see section 4.4). A reduced dose is advised.'; §4.4 adds 'Hydroxyzine is not recommended in elderly patients because of a decrease of hydroxyzine elimination in this population as compared to adults and the greater risk of adverse reactions (e.g. anticholinergic effects)'. Overarching rule, verbatim: 'Hydroxyzine Tablets should be used at the lowest effective dose and for the shortest possible duration.' The same SPC also carries a pruritus regimen (a secondary indication for this page), verbatim: 'Pruritis Adults Starting dose of 25mg at night increasing as necessary to 25mg three or four times daily.' — the same 100 mg/day adult ceiling applies to it. CROSS-CHECK DISCREPANCY, DO NOT USE IN THE UK: the US hydroxyzine pamoate label in this bundle states 'in adults, 50 mg to 100 mg q.i.d.' for anxiety (i.e. up to 400 mg/day) and 'As a sedative when used as a premedication and following general anesthesia: 50 mg to 100 mg in adults, and 0.6 mg/kg in children' — those are US figures, four times the UK total daily ceiling, and are not adopted here.

Paediatric dose

Route: Oral
Frequency: Daily in divided doses
Max: Maximum daily dose 100 mg per day in children and adolescents over 40 kg
dosePerKg is null deliberately: the SPC does not give a per-kg per-dose figure — it doses children by AGE BAND in fixed milligrams and uses weight only as a ceiling. Verbatim §4.2: 'From 6 months to 6 years, 5-15mg daily in divided doses adjusted depending on the child's weight.' and 'For children over 6 years, starting at 15-25mg and increasing to 50-100mg daily in divided doses adjusted according to the child's weight.' Weight-based ceiling for smaller children, verbatim: 'In children up to 40 kg in weight, the maximum daily dose is 2 mg/kg/day.' (that per-kg ceiling is recorded here rather than in maxDose on purpose). Over 40 kg, verbatim: 'In children and adolescents over 40kg in weight, the maximum daily dose is 100mg per day.' General rule, verbatim: 'As with all medications, the dosage should be adjusted according to the patient's response to therapy.' concentration is null: the bundle's product is a 10 mg film-coated TABLET and no oral solution strength appears anywhere in it, so no volume can be calculated. Verify the paediatric dose against a children's formulary before prescribing.

Dose adjustments

Renal

Verbatim §4.2: 'For patients with moderate or severe renal impairment, it is recommended that the total daily dosage should be reduced by 50% (see section 4.4 'Special Warnings and Precautions for Use').' §4.4 adds: 'Hydroxyzine Tablets should be used with caution in patients with impaired renal function... It is uncertain whether the drug may accumulate or have other adverse effects in such patients. Hydroxyzine Tablets are completely metabolised and one of the metabolites is the active metabolite cetirizine. Cetirizine is renally excreted and clearance is reduced in patients with moderate renal impairment and on dialysis compared to normal volunteers.'

Hepatic

Verbatim §4.2: 'The total daily dose should be reduced by 33%. Use in patients with severe liver disease should be avoided (see Section 4.4 ...).' §4.4 adds: 'Due to its sedative properties, use of hydroxyzine should be avoided in severe liver disease due to an increased risk of coma, and in patients with hepatic failure due to possibility of hepatic encephalopathy. Hydroxyzine elimination is impaired in patients with hepatic dysfunction secondary to primary biliary cirrhosis.'

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Previous hypersensitivity to hydroxyzine hydrochloride, cetirizine, other piperazine derivatives, aminophylline or ethylenediamine, or to any of the excipients (§4.3)
  • Known acquired or congenital QT interval prolongation (§4.3)
  • Known risk factor for QT interval prolongation — including known cardiovascular disease, significant electrolyte imbalance (hypokalaemia, hypomagnesaemia), family history of sudden cardiac death, significant bradycardia, or concomitant use with drugs known to prolong the QT interval and/or induce Torsade de Pointes (§4.3)
  • Asthmatics who have previously experienced a serious anti-histamine-induced adverse bronchopulmonary effect (§4.3)
  • Porphyria (§4.3)
  • Pregnancy and breast-feeding (§4.3, see §4.6)
  • Contains lactose — 'Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.' (§4.3)

Side effects

  • CNS depression is the most common effect of the sedating antihistamines — §4.8: 'Effects vary from slight drowsiness to deep sleep, and include lassitude, dizziness, and incoordination.' Paradoxical stimulation may occur, 'especially at high doses and in children and the elderly'
  • Nervous system (frequency not known): dyskinesia, insomnia, sedation, drowsiness, dizziness, weakness, headache, tremor, convulsions, psychomotor impairment, paraesthesias, extrapyramidal effects, seizure, coma, somnolence, disturbance in attention, involuntary motor activity, ataxia, slurred speech, bitter taste in mouth, faintness
  • Cardiac (frequency not known): ventricular arrhythmias (e.g. Torsade de Pointes), QT interval prolongation, tachycardia, palpitation
  • Vascular (frequency not known): hypotension, flushing
  • Antimuscarinic / gastrointestinal (frequency not known): dry mouth, constipation, nausea, vomiting, increased gastric reflux, diarrhoea, epigastric pain, increased GI peristalsis
  • Renal and urinary (frequency not known): urinary retention, dysuria
  • Eye and ear (frequency not known): accommodation disorder, blurred vision, tinnitus, labyrinthitis, vertigo
  • Psychiatric (frequency not known): agitation, confusion, disorientation, hallucinations, sleep disturbances, depression, increased anxiety, nightmares
  • Respiratory (frequency not known): bronchospasm, thickened respiratory tract secretions, wheezing, nasal stuffiness, dryness of throat
  • Skin (very rare for the listed severe reactions): dermatitis, fixed drug eruption, pruritus, erythema, papular rash, increased sweating, urticaria, hair loss, eczema, acute generalised exanthematous pustulosis (AGEP), toxic epidermal necrolysis, Stevens-Johnson syndrome, erythema multiforme
  • Blood (frequency not known): blood disorders including agranulocytosis, leucopenia, haemolytic anaemia and thrombocytopenia
  • Immune (frequency not known): hypersensitivity reactions, anaphylaxis, angioedema
  • Hepatobiliary (frequency not known): liver dysfunction; metabolic: porphyria, anorexia; musculoskeletal: myalgia; reproductive: priapism, impotence, early menses

Monitoring

  • The SPC has no dedicated monitoring section — the items below are the §4.3/§4.4 safety checks it does state. Before prescribing, screen for QT risk: §4.3 makes 'a known risk factor to QT interval prolongation' an absolute contraindication.
  • Cardiac symptoms on treatment — §4.4, verbatim: 'Treatment with hydroxyzine should be stopped if signs or symptoms occur that may be associated with cardiac arrhythmia, and the patients should seek immediate medical attention. Patients should be advised to promptly report any cardiac symptoms.'
  • Electrolytes — §4.3 lists 'significant electrolytes imbalance (hypokalaemia, hypomagnesaemia)' among the contraindicating QT risk factors; §4.4 notes that in post-marketing QT/torsade cases 'Most of these patients had other risk factors, electrolyte abnormalities and concomitant treatment that may have been contributory'.
  • Sedation and anticholinergic burden — §4.4 requires caution in angle-closure glaucoma, urinary retention, prostatic hyperplasia, pyroduodenal obstruction, decreased GI motility, bladder outflow obstruction, stenosing peptic ulcer, increased intraocular pressure, seizure disorders including epilepsy, myasthenia gravis, dementia, breathing problems (e.g. emphysema, chronic bronchitis) and hyperthyroidism.
  • Duration and dose — §4.2/§4.4, verbatim: 'Hydroxyzine should be used at the lowest effective dose and for the shortest possible duration.'
  • Renal and hepatic function — both drive a mandatory dose reduction (see renalAdjustment / hepaticAdjustment).

Clinical monograph

How it works

It is an antagonist at peripheral and central histamine H1 receptors, producing sedative, anxiolytic and antipruritic effects.

Prescribing in practice

  • It can prolong the QT interval and has been associated with torsades de pointes, so avoid in patients with known QT prolongation or significant cardiac risk factors and use the lowest effective dose for the shortest time.
  • Marked sedation and antimuscarinic effects can occur, so use with caution in the elderly and in those with urinary retention, glaucoma or prostatic enlargement.
  • Avoid concurrent use with other medicines that prolong the QT interval or have additive sedative effects.

Monitoring

Assess cardiac risk factors before starting and review for excessive sedation and antimuscarinic effects, with ECG consideration in those at risk of QT prolongation.

Counselling the patient

  • Warn that drowsiness is common and may impair driving and skilled tasks.
  • Avoid alcohol while taking this medicine.
  • Seek urgent advice if palpitations or fainting occur.

Evidence & guidelines

The MHRA has highlighted the risk of QT-interval prolongation and torsades de pointes with hydroxyzine, supporting cautious use as detailed in current prescribing references.

Reference: NICE NG106 (GAD); MHRA Hydroxyzine Safety Update 2015; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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