Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ATARAX vs ACTIDIL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: June 2026 · OpiCalc Medical Review Team
Hydroxyzine is a piperazine derivative with antihistaminic (H1-receptor antagonist) and anticholinergic properties; also exhibits sedative, anxiolytic, and antiemetic effects due to suppression of activity in subcortical areas of the CNS.
H1-receptor antagonist; competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract, blocking histamine-induced bronchoconstriction, vasodilation, and increased capillary permeability.
Pruritus due to allergic conditions (FDA approved),Anxiety and tension (FDA approved for psychoneurosis),Sedation before and after general anesthesia (FDA approved),Off-label: Nausea and vomiting, motion sickness, insomnia
Allergic rhinitis,Allergic conjunctivitis,Urticaria,Angioedema
25 mg orally 3-4 times daily; maximum 100 mg per day. Also available as 50 mg intramuscular injection every 4-6 hours.
2.5 mg orally every 4 to 6 hours as needed; maximum 10 mg per day.
Terminal elimination half-life is approximately 20-25 hours in healthy adults; may be prolonged in elderly, hepatic impairment, or renal insufficiency (up to 30-40 hours); steady-state achieved within 3-4 days.
Terminal elimination half-life is approximately 20-25 hours in healthy adults; may be prolonged in elderly or patients with hepatic impairment.
Primarily hepatic via CYP3A4 and CYP2D6; major metabolite is cetirizine.
Hepatic via CYP450 isoenzymes (primarily CYP3A4 and CYP2D6); undergoes N-demethylation and N-oxidation.
Primarily hepatic metabolism via CYP3A4 and CYP2D6; renal excretion of metabolites accounts for approximately 70-80% of the dose, with less than 1% excreted unchanged; fecal excretion is about 10-15%.
Renal excretion of unchanged drug and metabolites accounts for approximately 60-80% of the administered dose; biliary/fecal elimination comprises the remainder (20-40%).
Approximately 93% bound primarily to albumin and alpha-1-acid glycoprotein.
Approximately 90% bound to plasma proteins, primarily albumin.
Approximately 10-15 L/kg; large Vd indicates extensive tissue distribution, including penetration into the central nervous system.
2.5-4.0 L/kg, indicating extensive tissue distribution.
Oral bioavailability is approximately 100% (nearly complete absorption) with peak plasma concentrations at 2 hours; intramuscular bioavailability is similar to oral but with faster absorption.
Oral bioavailability is approximately 50-60% due to first-pass metabolism.
GFR 10-50 m L/min: administer every 24 hours. GFR <10 m L/min: contraindicated or reduce dose to 50% every 24 hours.
GFR 10-50 m L/min: 2.5 mg every 6-8 hours; GFR <10 m L/min: 2.5 mg every 8-12 hours.
Child-Pugh Class A: no adjustment. Class B: reduce dose by 50%. Class C: contraindicated.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: contraindicated.
Children >6 years: 0.6 mg/kg orally every 6 hours; maximum 2 mg/kg/day. Children <6 years: 0.5 mg/kg orally every 4-6 hours; maximum 50 mg/day.
Children 2-5 years: 1.25 mg orally every 4-6 hours (max 5 mg/day); Children 6-12 years: 1.25-2.5 mg every 4-6 hours (max 7.5 mg/day).
Initiate at 12.5 mg orally twice daily; may increase gradually. Avoid use in patients with significant renal impairment or dementia due to anticholinergic effects.
Initiate at 1.25 mg orally every 6-8 hours; maximum 5 mg per day due to increased risk of anticholinergic effects and renal impairment.
Not applicable; no black box warning.
None
Drowsiness and impairment of alertness; avoid driving or operating machinery,Potentiation of CNS depressants (alcohol, barbiturates, opioids),Anticholinergic effects (urinary retention, blurred vision, constipation),QT prolongation risk (especially with electrolyte disturbances, pre-existing QT prolongation, or concurrent QT-prolonging drugs),Use with caution in elderly due to increased risk of sedation and falls,Tardive dyskinesia with prolonged high-dose use
May cause drowsiness and impair mental alertness,Avoid alcohol and other CNS depressants,Use with caution in patients with narrow-angle glaucoma, prostatic hypertrophy, or urinary retention,Elderly patients are more susceptible to anticholinergic effects
Hypersensitivity to hydroxyzine or any component of the formulation,Early pregnancy (first trimester) due to potential fetal harm,Porphyria,Lactation (excreted in breast milk)
Hypersensitivity to any component,Concurrent use with monoamine oxidase inhibitors
No significant food interactions reported. However, alcohol should be avoided due to additive CNS depression. Grapefruit juice may theoretically increase hydroxyzine levels via CYP3A4 inhibition, but clinical significance is minimal; caution is advised.
No specific food interactions, but taking with food may reduce GI side effects. Alcohol should be strictly avoided due to additive CNS depression. Grapefruit juice is not documented to interact.
First trimester: Considered safe; large studies show no increased risk of major malformations. Second trimester: No known specific risks. Third trimester: Use near term may cause neonatal withdrawal or CNS depression (drowsiness, irritability, tremors) due to placental transfer.
First trimester: Limited human data; animal studies show no teratogenicity. Second and third trimesters: Not associated with major congenital malformations. However, anticholinergic effects may cause neonatal tachycardia, irritability, and withdrawal symptoms if used near term.
Atarax (hydroxyzine) is excreted into breast milk in small amounts; M/P ratio approximately 0.7. Use with caution; monitor infant for sedation, irritability, or feeding difficulties. The American Academy of Pediatrics considers it compatible with breastfeeding, but alternative agents may be preferred.
Excretion into breast milk likely but negligible amounts; no adverse effects reported in infants. M/P ratio not established. Considered compatible with breastfeeding; monitor for sedation or irritability in neonate.
No dose adjustment is typically required for non-sedating use. However, pharmacokinetic changes in pregnancy (increased plasma volume, altered clearance) may necessitate cautious titration; start at lowest effective dose and adjust based on clinical response. For severe pruritus in pregnancy, typical adult dosing (25 mg tid or qid) is used, but monitor for excessive sedation.
No specific dose adjustments required in pregnancy; however, use lowest effective dose due to potential anticholinergic effects. Pharmacokinetics may be altered (increased volume of distribution), but no dose adjustment recommended.
ATARAX (hydroxyzine) is a first-generation antihistamine with anxiolytic and sedative properties. It is commonly used for pruritus, anxiety, and preoperative sedation. Note: QT prolongation risk at high doses; avoid in patients with known QT interval prolongation or concurrent use of other QT-prolonging agents. Onset of sedation is rapid, making it useful for sleep induction, but tolerance develops with chronic use. Anticholinergic effects (dry mouth, urinary retention) are dose-dependent.
ACTIDIL (triprolidine) is a first-generation antihistamine with sedative properties. Use cautiously in elderly due to risk of confusion, urinary retention, and falls. Avoid in patients with narrow-angle glaucoma, BPH, or asthma. Administer with food if GI upset occurs. Onset of action is 30-60 minutes; duration 4-6 hours.
Take exactly as prescribed; do not exceed recommended dose.,Avoid alcohol and other CNS depressants (e.g., benzodiazepines, opioids) as they may increase drowsiness and dizziness.,Do not drive or operate heavy machinery until you know how this medication affects you.,Report any signs of allergic reaction (rash, difficulty breathing) or irregular heartbeat (palpitations, syncope) immediately.,Hydrate adequately to reduce dry mouth; sugar-free gum or candy can help.,Do not discontinue abruptly; follow your doctor's instructions for tapering if needed.
Do not drive or operate heavy machinery until you know how this medication affects you; it can cause drowsiness.,Avoid alcohol and other CNS depressants, as they may increase sedation.,Take exactly as prescribed; do not exceed recommended dose.,If you miss a dose, skip it; do not double the next dose.,Notify your doctor if you experience blurred vision, difficulty urinating, or severe drowsiness.,Do not use for prolonged periods without medical advice.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ATARAX vs ACTIDIL, answered by our medical review team.
ATARAX is a Antihistamine that works by Hydroxyzine is a piperazine derivative with antihistaminic (H1-receptor antagonist) and anticholinergic properties; also exhibits sedative, anxiolytic, and antiemetic effects due to suppression of activity in subcortical areas of the CNS.. ACTIDIL is a Antihistamine that works by H1-receptor antagonist; competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract, blocking histamine-induced bronchoconstriction, vasodilation, and increased capillary permeability.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ATARAX and ACTIDIL depend on the specific clinical indication. These are both Antihistamine agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ATARAX is: 25 mg orally 3-4 times daily; maximum 100 mg per day. Also available as 50 mg intramuscular injection every 4-6 hours.. The standard adult dose of ACTIDIL is: 2.5 mg orally every 4 to 6 hours as needed; maximum 10 mg per day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between ATARAX and ACTIDIL in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. ATARAX is classified as Category C. First trimester: Considered safe; large studies show no increased risk of major malformations. Second trimester: No known specific risks. Third trimester: Use near term may cause n. ACTIDIL is classified as Category C. First trimester: Limited human data; animal studies show no teratogenicity. Second and third trimesters: Not associated with major congenital malformations. However, anticholinergi. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.