HYDROXYZINE (Vistaril): What is used for?

What is Hydroxyzine?

Hydroxyzine (Hidroxizina) is a drug used for the treatment of anxiety, pruritus and urticaria. The product ingredients are Hydroxyzine hydrochloride (hcl) and Hydroxyzine pamoate.

The brand names of Hydroxyzine in United States are: Vistaril, Atarax, Hyzine.

Mechanism of action (MOA) of Hydroxyzine

Its action may be due to a suppression of activity in certain regions of the subcortical area of the CNS. It has anxiolytic, antiemetic, antihistamine and bronchodilator activity, antispasmodic and sympathicolytic effects.

Therapeutic indications, uses and benefits of Hydroxyzine

Symptomatic treatment of anxiety in adults. Symptomatic treatment of pruritus and urticaria. Premedication before anaesthesia in adults and children (> 6 years for solid oral forms; > 30 months for liquid oral forms).

Hydroxyzine dosage

– Symptomatic treatment of anxiety: 50-100 mg/day in 3 doses of 12.5-25 mg, 12.5-25 mg, 25-50 mg.
– Symptomatic treatment of pruritus and urticaria: 25 mg at night, increase 25 mg/3 times/day, if necessary.
– Premedication before anaesthesia: 50-100 mg/day in 1 or 2 doses. Maximum adult dose: 100 mg/day.
Children from 12 months:
– Symptomatic treatment of pruritus and urticaria: 1 mg/kg/day to 2 mg/kg/day in several doses. In children weighing up to 40 kg, the maximum daily dose is 2 mg/kg/day.
– Premedication before anaesthesia: single dose of 0.6 mg/kg 1 h before the operation, which may be preceded by 0.6 mg/kg the night before the anaesthesia.
Accumulated dose in 24 h: should not exceed 2 mg/kg/day. Maximum dose in children 2 mg/kg/day in children up to 40 kg.
Liver failure reduce daily dose by 33%. Moderate or severe renal insufficiency reduce dose.

Contraindications of Hydroxyzine

  • Hypersensitivity to hydroxyzine, cetirizine, other piperazine derivatives, aminophylline or ethylenediamine. Porphyria.
  • Pregnancy and lactation.
  • With prolongation of the congenital or acquired QT interval.
  • With known predisposing risk factors for prolongation of the QT interval including pre-existing cardiovascular disease, alterations of electrolyte balance (hypokalemia, hypomagnesemia), family history of sudden cardiac death, significant bradycardia and concomitant use of substances with recognized potential to produce prolongation of the QT interval and/or induce Torsade de Pointes.

Warnings and precautions with Hydroxyzine

Moderate or severe renal failure.

Liver failure.

Elderly (not recommended).


Obstruction of bladder flow.

Decreased gastrointestinal motility.

Myasthenia gravis or dementia.

High risk of convulsions, especially in children.

Risk of prolongation of the QT interval, if signs or symptoms appear that may be associated with cardiac arrhythmia, discontinue treatment.

Liver failure

Caution. Dose reduction is recommended.

Kidney failure

Caution in moderate or severe renal failure. It is recommended to reduce the dose, decreases the excretion of the metabolite cetirizine.

Interactions with hydroxyzine

  • Increase the risk of cadiac arrhythmia with: substance known to prolong the QT interval and/or induce Torsade de Pointes, e.g. class IA (e.g. quinidine, disopyramide) and class III (e.g. amiodarone, sotalol) antiarrhythmics, some antihistamines, some antipsychotics (e.g. haloperidol), some antipsychotics (e.g. haloperidol).
  • Antidepressants (e.g. citalopram, escitalopram), some antimalarial drugs (e.g. mefloquine and hydroxychloroquine), some antibiotics (e.g. erythromycin, levofloxacin, moxifloxacin), some antifungal agents (e.g. pentamidine), some gastrointestinal agents (e.g. prucalopride), some cancer agents (e.g. toremifen, vandetanib), or methadone. This association is contraindicated
    effects enhanced by: alcohol.
  • Plasma concentration increased by: cimetidine.
  • Avoid simultaneous administration with: MAOI.
  • Counterpressive action of: adrenaline.
  • Antagonizes effects of: betahistidine and anticholinesterase drugs.
  • Caution when administered with other substances capable of producing hypokalemia and/or bradycardia.
  • Lob: interferes with the results of allergy test or bronchial provocation test with metacholine.

Pregnancy and Hydroxyzine



It is contraindicated during lactation. If hydroxyzine therapy is necessary, lactation should be discontinued.

Effects on driving ability

Hydroxyzine, depending on the dose and individual sensitivity, may decrease attention, alter the ability to react and produce drowsiness, amnesia or sedation, especially at the start of treatment or after an increase in dose.

It is not advisable to drive vehicles or operate machinery whose use requires special attention or concentration, until it is proven that the ability to perform these activities is not affected.

Adverse reactions and side effects of Hydroxyzine

Drowsiness, headache, fatigue, dry mouth, sedation.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


PubChem CID: 3658
NCI Thesaurus: C29103

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