Hydroxyzine: Nursing Drug Guide, CNS Sedation Stacking & NCLEX Review

Hydroxyzine is available as hydroxyzine hydrochloride (HCl) and hydroxyzine pamoate salts. Both are first-generation agents with sedating and anticholinergic effects. Pamoate capsules are labeled as equivalent to hydroxyzine HCl strengths (e.g., 25 mg or 50 mg HCl). This guide focuses on oral and intramuscular use per U.S. prescribing information.

• Hydrochloride: Atarax tablets (10, 25, 50, 100 mg) and syrup (10 mg per 5 mL; syrup contains alcohol per Atarax labeling)
• Pamoate: Vistaril and generics—capsules commonly 25 mg and 50 mg (equivalent to HCl)
• Routes: Oral tablets, capsules, syrup; IM initiation with subsequent oral doses allowed per labeling
• Active metabolite context: Parent compound of cetirizine—cross-sensitivity contraindications apply on current pamoate labeling
• Less sedating alternatives: loratadine or fexofenadine when sedation burden is unacceptable (different profiles)

Per Atarax (hydroxyzine HCl) and hydroxyzine pamoate prescribing information:

• Anxiety and tension: Symptomatic relief associated with psychoneurosis and as an adjunct when anxiety is manifested in organic disease states
• Pruritus: Allergic conditions such as chronic urticaria and atopic/contact dermatoses, and histamine-mediated itch—often with hives or allergies
• Sedation: Premedication and post–general anesthesia sedation; may potentiate meperidine and barbiturates—doses of those agents should be modified individually
• Long-term anxiety: Effectiveness beyond 4 months has not been assessed by systematic studies—periodic reassessment required per labeling
• Hospital nursing context: PRN anxiety, itch, or pre-procedure calming per order—not a substitute for definitive treatment of long-term anxiety disorders or anaphylaxis pathways

Hydroxyzine is unrelated chemically to phenothiazines, reserpine, meprobamate, and benzodiazepines per labeling. It is not a cortical depressant; action may involve suppression of activity in subcortical CNS regions.

Experimentally and clinically it shows antihistaminic, bronchodilator, antiemetic, and mild antisecretory activity. At therapeutic doses it generally does not increase gastric secretion or acidity per labeling.

Because it is sedating and anticholinergic, nurses should expect drowsiness, dry mouth, and additive depression with other CNS depressants—especially in older adults.

Match salt, strength, and indication to the order. Dosage should be adjusted according to the patient’s response per labeling. Verify institutional protocol for IM-to-oral conversion.

Anxiety and tension — adults (Atarax HCl and pamoate labeling)

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Pruritus — adults and children (labeling)

Premedication / post-anesthesia sedation

• Adults: 50–100 mg
• Children: 0.6 mg/kg
• When treatment begins IM, subsequent doses may be given orally per labeling

Maximum daily limits for all indications combined: Not specified in the reviewed prescribing information as a single explicit cap—calculate total 24-hour hydroxyzine from all scheduled and PRN doses and clarify with pharmacy if multiple indications are ordered.

• Absorption: Rapidly absorbed from the GI tract per labeling
• Onset: Clinical effects usually noted within 15 to 30 minutes after oral administration
• Distribution/metabolism/elimination half-life: Not specified in the reviewed prescribing information
• Renal excretion: Extent of renal excretion has not been determined—use caution selecting doses in elderly patients with decreased renal function per geriatric labeling

Answer these before the first dose or when reconciling home medications:

• Correct patient, salt (HCl vs pamoate), strength, route, and scheduled time
• Indication-specific dose—anxiety regimens differ from pruritus regimens; do not borrow doses across indications
• CNS depressants: opioids (oxycodone, morphine), benzodiazepines (lorazepam, alprazolam), barbiturates, alcohol
• Only one sedating antihistamine for overlapping symptoms unless documented otherwise
• QT risk: prolonged QT, recent MI, uncompensated heart failure, bradyarrhythmias, electrolyte imbalance, or QT-prolonging drugs (e.g., antiarrhythmics, some antipsychotics/antibiotics per pamoate labeling)
• Pregnancy: contraindicated in early pregnancy per labeling; confirm status
• Lactation: labeling advises not giving to nursing mothers
• Cross-allergy: hypersensitivity to hydroxyzine, cetirizine, or levocetirizine per pamoate labeling
• Older adult: baseline cognition, fall risk, orthostatic symptoms
• Perform medication reconciliation including PRN anxiety and allergy meds per medication reconciliation protocol

• Early pregnancy—animal studies showed fetal abnormalities at doses above human therapeutic range; human data inadequate per Atarax and pamoate labeling
• Hypersensitivity to hydroxyzine or formulation components
• Prolonged QT interval (hydroxyzine pamoate labeling)
• Known hypersensitivity to cetirizine or levocetirizine (pamoate labeling)

Nursing mothers: labeling states hydroxyzine should not be given to nursing mothers because excretion in human milk is not known (warnings section).

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Oral

• May give with or without food unless institutional policy states otherwise—Not specified in the reviewed prescribing information
• Syrup: 10 mg per teaspoon (5 mL); contains alcohol per Atarax labeling—consider in patients who must avoid alcohol
• Use calibrated device for liquids; confirm mg per 5 mL on each product

Intramuscular

• When IM therapy initiates treatment, subsequent doses may be oral per labeling
• Document exact mg, route, time, and prescriber indication
• Follow medication administration rights and institutional IM policy

• Reduced anxiety or tension within 15–30 minutes of oral dose per pharmacology labeling
• Decreased pruritus and improved comfort with urticaria or allergic itch
• Appropriate sedation when used preoperatively—without excessive respiratory depression at recommended doses (clinically significant respiratory depression not reported at recommended doses per labeling)
• If symptoms persist at maximum labeled dosing for the indication, contact prescriber rather than adding another sedating antihistamine

• Unable to arouse, respiratory depression, or severe altered mental status—especially with CNS depressants
• New confusion, hallucinations, or tremor—may occur at doses higher than recommended per labeling
• Palpitations, syncope, or ECG changes suggesting QT prolongation / Torsade de Pointes
• Fever with widespread pustules on erythematous skin—consider AGEP; discontinue hydroxyzine per pamoate labeling
• Generalized rash, angioedema, or bronchospasm—stop drug; manage per emergency pathway if systemic allergic reaction
• Paradoxical agitation (more common in children with sedating drugs per geriatric/pediatric caution context)—notify prescriber

Reported effects are usually mild and transitory per labeling. Nursing priorities: sedation, CNS potentiation, anticholinergic effects, and cardiac QT signals (pamoate labeling).

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The most common manifestation of overdosage is hyperedation per labeling. Pamoate labeling also reports convulsions, stupor, nausea, and vomiting. Assume multiple agents may have been ingested.

Antidote

No specific antidote is listed. Management is supportive:

• Induce vomiting if not spontaneous; gastric lavage recommended per labeling
• Monitor vital signs closely; hypotension may be treated with IV fluids and vasopressors
• Do not use epinephrine—hydroxyzine counteracts its pressor action
• ECG monitoring recommended in overdose because of QT prolongation risk (pamoate labeling)
• Caffeine and sodium benzoate injection may counteract CNS depressant effects (pamoate labeling)
• Hemodialysis unlikely to help hydroxyzine alone; may be indicated if barbiturates co-ingested

• Hydroxyzine vs hydralazine—high-risk sound-alike; verify indication (itch/anxiety vs hypertension)
• Hydroxyzine HCl vs hydroxyzine pamoate—both labeled as HCl-equivalent strengths but different products; confirm correct capsule/tablet
• Atarax vs Vistaril—brand confusion between HCl and pamoate lines
• 25 mg vs 50 mg vs 100 mg—anxiety regimens use higher daily totals than pruritus
• Hydroxyzine vs cetirizine/levocetirizine—related chemistry; cross-sensitivity contraindication on pamoate labeling
• Stacking with diphenhydramine or promethazine—duplicate sedating antihistamine therapy

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Monitor

• Level of sedation, orientation, respiratory rate, and safe ambulation
• Blood pressure and heart rate—orthostatic symptoms in older adults
• Pruritus or anxiety symptom response versus adverse CNS effects
• ECG or telemetry when QT risk factors present and patient symptomatic—institutional protocol
• Skin for new rash, pustules, or worsening itch after dose

Document

• Indication, salt, dose, route, time, and 24-hour cumulative hydroxyzine total
• CNS depressant co-therapy and patient counseling on alcohol/machinery
• Sedation scale and fall precautions in older adults
• Prescriber/pharmacy notification when hold criteria met

Routine serum hydroxyzine levels: Not specified in the reviewed prescribing information for therapeutic monitoring.

• This medicine causes drowsiness—do not drive or operate dangerous machinery until you know how you respond
• Do not drink alcohol or take other sedating medicines unless the prescriber approves—effects may be increased per labeling
• Do not start another sedating allergy or sleep medicine without checking with your care team
• Report extreme sleepiness, confusion, palpitations, fainting, or rash with fever/pustules immediately
• If you are pregnant, planning pregnancy, or breastfeeding—discuss before taking hydroxyzine
• If you have ever reacted to cetirizine (Zyrtec) or levocetirizine—tell your nurse before hydroxyzine
• Store securely away from children—overdose causes dangerous sedation

Do not give and contact the prescriber/pharmacist when:

Hold parameters may vary by institutional protocol. Follow prescriber orders, pharmacy guidance, and facility policy.