Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ATARAX vs ACTAHIST
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.
Antihistamine; binds to histamine H1 receptors, blocking the effects of histamine; also exhibits anticholinergic and mild sedative properties.
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
Symptomatic relief of allergic rhinitis,Urticaria,Off-label: motion sickness,Off-label: insomnia
25 mg orally 3-4 times daily; maximum 100 mg per day. Also available as 50 mg intramuscular injection every 4-6 hours.
1.34 mg (one capsule) orally twice daily.
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.
6.9 ± 1.7 hours in adults; prolonged to 12-18 hours in elderly or patients with hepatic impairment, requiring dosing interval adjustment.
Primarily hepatic via CYP3A4 and CYP2D6; major metabolite is cetirizine.
Hepatic metabolism via CYP450 enzymes (primarily CYP3A4 and CYP2D6); major metabolite is inactive.
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%.
Primarily renal (approximately 85% as unchanged drug and metabolites) and fecal (15%) via biliary elimination.
Approximately 93% bound primarily to albumin and alpha-1-acid glycoprotein.
92% bound to albumin.
Approximately 10-15 L/kg; large Vd indicates extensive tissue distribution, including penetration into the central nervous system.
0.9 ± 0.3 L/kg, indicating extensive extravascular 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: 68% ± 12% 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.
No dose adjustment required for mild to moderate renal impairment. Safety not established for severe impairment (GFR <30 m L/min).
Child-Pugh Class A: no adjustment. Class B: reduce dose by 50%. Class C: contraindicated.
No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not recommended for severe hepatic impairment (Child-Pugh C).
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.
Not indicated for pediatric patients under 12 years of age. Safety and efficacy not established.
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.
No specific dose adjustment recommended; monitor for increased anticholinergic effects and cognitive 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; caution when driving or operating machinery. Avoid alcohol. Use with caution in patients with narrow-angle glaucoma, prostatic hyperplasia, or urinary retention. Geriatric patients more sensitive to anticholinergic effects. Pediatric patients <6 years: not recommended.
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. Newborns or premature infants. Breastfeeding (contraindicated due to risk of adverse effects in infants). Concomitant use with MAOIs.
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.
Avoid high-tyramine foods (aged cheese, cured meats, fermented products) if taking MAOIs. Grapefruit juice may increase phenylephrine absorption; limit intake.
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.
ACTAHIST (brompheniramine/phenylephrine) pregnancy category C. Inadequate human data; animal studies show no malformations at therapeutic doses. First trimester: theoretical risk from vasoconstrictive effects (phenylephrine) possibly reducing uterine blood flow; avoid if possible. Second/third trimester: phenylephrine may cause fetal hypoxia via placental vasoconstriction; use only if benefit outweighs risk. No known structural teratogenicity.
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.
Brompheniramine is excreted in breast milk in small amounts; M/P ratio not established. Phenylephrine has minimal excretion. Due to anticholinergic effects, may reduce milk production or cause sedation in infants. Use caution; prefer non-sedating alternatives if possible.
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 pharmacokinetic studies. Increased plasma volume and renal clearance in pregnancy may reduce drug levels, but efficacy threshold remains. No dose adjustment recommended; use the lowest effective dose for shortest duration due to potential risks.
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.
Actahist is a combination antihistamine-decongestant (chlorpheniramine/phenylephrine). Avoid in patients with hypertension, severe coronary artery disease, or MAOI use. Monitor for sedation and urinary retention, especially in elderly males with BPH.
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.
Take with food or milk to reduce stomach upset.,Avoid alcohol and CNS depressants as they can increase drowsiness.,Do not drive or operate machinery until you know how this medication affects you.,Contact your doctor if you experience chest pain, rapid heartbeat, or difficulty urinating.
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 ACTAHIST, 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.. ACTAHIST is a Antihistamine that works by Antihistamine; binds to histamine H1 receptors, blocking the effects of histamine; also exhibits anticholinergic and mild sedative properties.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ATARAX and ACTAHIST 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 ACTAHIST is: 1.34 mg (one capsule) orally twice daily.. 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 ACTAHIST 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. ACTAHIST is classified as Category C. ACTAHIST (brompheniramine/phenylephrine) pregnancy category C. Inadequate human data; animal studies show no malformations at therapeutic doses. First trimester: theoretical risk f. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.