Hydroxyzine (Atarax) Adverse Reactions
- abdominal pain
- agitation
- appetite stimulation
- asthenia
- ataxia
- blurred vision
- confusion
- constipation
- contact dermatitis
- dizziness
- drowsiness
- dysarthria
- dyskinesia
- dystonic reaction
- fatigue
- hallucinations
- headache
- hemolysis
- hypotension
- impaired cognition
- injection site reaction
- insomnia
- maculopapular rash
- mydriasis
- palpitations
- priapism
- psychosis
- rash (unspecified)
- respiratory depression
- restlessness
- seizures
- sinus tachycardia
- tardive dyskinesia
- thrombosis
- tissue necrosis
- tremor
- urinary retention
- urticaria
- weakness
- xerophthalmia
- xerostomia
Hydroxyzine (Atarax) Adverse Reactions
The most frequently reported adverse reaction to hydroxyzine is xerostomia (dry mouth), resulting from the anticholinergic effects of the drug. Peripheral neurologic effects due to cholinergic blockade may include dilated pupils (mydriasis) or blurred vision, xerophthalmia, and urinary retention (especially in males). H1-antagonists may cause adverse GI effects including constipation or abdominal pain. Stomach upset may be relieved by taking the drug with food. Elderly persons usually have the greatest risk of experiencing anticholinergic-related side effects.
Common side effects of hydroxyzine and other sedating antihistamines include drowsiness and decreased alertness. An important consequence of this action may be the impairment of driving ability. With hydroxyzine, drowsiness or fatigue is usually transient, and continued therapy or dosage reduction can diminish this effect. After a bedtime dose of hydroxyzine, most patients feel fully awake the following morning. However, temporarily impaired cognition has been reported in clinical use. A small study showed that hydroxyzine produced less sedation than either azatadine or clemastine. Other less frequently occurring CNS effects of sedating antihistamines include dizziness, asthenia/weakness, dysarthria (slurred speech), confusion, or headache. Elderly persons and pediatric patients taking classic antihistamines have the greatest risk of CNS related side effects. Hydroxyzine, like many antihistamines, can cause CNS stimulation, although, this is more likely to occur in children. Other stimulatory reactions may include appetite stimulation, agitation or muscle spasms. The anticholinergic reactions of insomnia, nervousness or restlessness, irritability, palpitations, and sinus tachycardia may also occur.
Drug allergy has been reported with hydroxyzine, although rare. Cases have included contact dermatitis, fixed drug eruptions of the penis or scrotum, maculopapular rash, rash (unspecified), and urticaria.
Antihistamine overdose has been linked to coma; stimulatory CNS effects such as dyskinesia, dystonic reaction, tardive dyskinesia, tremor and seizures; and neuropsychiatric effects such as hallucinations or psychosis. Rarely, ataxia and delirium are also seen. Fatalities have been reported with overdose.
Priapism (prolonged penile erections) have been reported very rarely in the literature with hydroxyzine. Norchlorcyclizine (a hydroxyzine metabolite), has structural similarities to a trazodone metabolite, m-chlorophenylpiperazine, suggesting potential mechanistic similarities. It should be noted that causality between priapism and hydroxyzine has not been established.
An injection site reaction is possible after the intramuscular (IM) injection of hydroxyzine and can include erythema, local irritation, and tissue necrosis. Care should be taken to avoid extravasation or inadvertant parenteral administration by other routes. Hydroxyzine is not recommended for intravenous (IV) administration since it can cause serious adverse effects, including hemolysis. Severe local reactions from inadvertent intravenous or intra-arterial administration have included thrombophlebitis, thrombosis and tissue necrosis (gangrene). Subcutaneous injection may also result in severe local tissue damage.
While oral or intramuscular therapeutic dosages of hydroxyzine (a piperazine derivative) have minimal effects on blood pressure, overdosage or inadvertant routes of administration may magnify the hypotensive and sedative effects. Hypotension and sedation with parenteral hydroxyzine, including intramuscular administration, may be particularly relevant when the drug is administered along with a parenteral opiate or other sedative. Do not give hydroxyzine intravenously or intra-arterially. In one study, intravenous (IV) hydroxyzine doses of 0.75 - 1 mg/pound to young adults resulted in sinus tachycardia and hypotension. Other cases of respiratory depression or cardiovascular instability following intravenous use of hydroxyzine have been reported, mostly as uncontrolled case reports in the literature. Investigations supporting the side effects of intravenous hydroxyzine were primarily performed in the mid-to-late 1960s and 1970s. At that time, intravenous use of hydroxyzine quickly fell out of favor and IV administration is now contraindicated.
[ Last revised: 12/11/2002 3:49:00 PM ]
References
. Levander S, Hagermark O, Stahle M. Peripheral antihistamine and central sedative effects of three H1-receptor antagonists. Eur J Clin Pharmacol 1985;28:523 - 9.
. Linder GS, Dillon JB. Hydroxyzine hemolysis in surgical patients. Anesth Analg 1967;46:90 - 5.
. Lauria JI et al. Circulatory and respiratory effects of hydroxyzine in volunteers and geriatric patients. Anesth Analg 1968;47:378 - 82.
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