Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
VISTARIL vs ACTIDIL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Hydroxyzine is a piperazine derivative antihistamine that acts as a competitive antagonist of histamine H1 receptors, thereby suppressing histamine activity in the subcortical area of the central nervous system. It also has anxiolytic, sedative, antiemetic, and antispasmodic effects.
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.
Anxiety and tension associated with psychoneurosis,Pruritus due to allergic conditions (e.g., urticaria, atopic dermatitis),Sedation prior to dental or surgical procedures,Nausea and vomiting (off-label)
Allergic rhinitis,Allergic conjunctivitis,Urticaria,Angioedema
Oral: 50-100 mg 4 times daily; IM: 25-100 mg every 4-6 hours as needed.
2.5 mg orally every 4 to 6 hours as needed; maximum 10 mg per day.
Terminal elimination half-life: 20-25 hours in adults; prolonged in hepatic impairment or elderly; steady-state achieved in ~4-5 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 metabolites include cetirizine.
Hepatic via CYP450 isoenzymes (primarily CYP3A4 and CYP2D6); undergoes N-demethylation and N-oxidation.
Primarily hepatic metabolism; <1% excreted unchanged in urine; biliary/fecal elimination of metabolites accounts for approximately 50-60% of total clearance.
Renal excretion of unchanged drug and metabolites accounts for approximately 60-80% of the administered dose; biliary/fecal elimination comprises the remainder (20-40%).
Highly protein-bound: approximately 89-93%, primarily to albumin.
Approximately 90% bound to plasma proteins, primarily albumin.
Volume of distribution: 7-10 L/kg, indicating extensive tissue distribution.
2.5-4.0 L/kg, indicating extensive tissue distribution.
Oral: incomplete bioavailability due to first-pass metabolism, estimated at 40-60%; IM: nearly complete (85-100%).
Oral bioavailability is approximately 50-60% due to first-pass metabolism.
No specific adjustment; use with caution in severe renal impairment due to potential accumulation of metabolites.
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; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: avoid use.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: contraindicated.
Oral: 0.5-1 mg/kg every 4-6 hours; maximum 50 mg per dose (≤12 years); IM: 0.5-1 mg/kg every 4-6 hours.
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).
Start at lower end of dosing range (e.g., 25 mg oral 3-4 times daily); monitor for sedation and 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.
No FDA black box warning.
None
May cause QT prolongation; use with caution in patients with risk factors (e.g., electrolyte imbalance, concomitant QT-prolonging drugs),Sedation and impaired cognitive/motor function; avoid driving or hazardous activities,Anticholinergic effects (e.g., urinary retention, constipation); use cautiously in elderly or patients with prostatic hypertrophy,Respiratory depression with concurrent CNS depressants,Use in pregnancy: avoid especially during early pregnancy; may increase risk of fetal abnormalities
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,Early pregnancy (first trimester),Porphyria,Breastfeeding (use caution)
Hypersensitivity to any component,Concurrent use with monoamine oxidase inhibitors
Alcohol increases sedation and CNS depression; avoid concurrent use. No significant food interactions, but take with food if GI upset occurs.
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: Limited human data; animal studies suggest no major teratogenic risk; fetal harm cannot be ruled out. Second and third trimesters: Hydroxyzine may cause neonatal withdrawal symptoms (irritability, tremors) with chronic maternal use near term; no evidence of structural anomalies.
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.
Hydroxyzine is excreted in human milk; M/P ratio not established. Potential for adverse effects in infants (sedation, irritability). Use during breastfeeding only if clearly needed; monitor infant for drowsiness.
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 specific dose adjustments recommended in pregnancy; use lowest effective dose. Hydroxyzine may be less effective if used as an antiemetic due to altered clearance; consider alternative agents.
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.
VISTARIL (hydroxyzine pamoate) is a first-generation antihistamine with anxiolytic and sedative properties. It is often used for preoperative sedation, pruritus, and anxiety. Onset of sedation is rapid (15-30 minutes) but duration is short (4-6 hours). It has anticholinergic effects; caution in elderly and patients with glaucoma or prostatic hypertrophy. Do not administer intra-arterially or subcutaneously (risk of hemolysis or tissue necrosis). It is not a controlled substance, but has abuse potential. May cause significant somnolence; advise against driving or operating machinery.
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 as prescribed; do not exceed recommended dose.,May cause drowsiness; avoid driving or heavy machinery until you know how it affects you.,Avoid alcohol and other CNS depressants.,Report any signs of allergic reaction (rash, difficulty breathing) immediately.,Do not stop abruptly without consulting doctor.,Store at room temperature away from moisture and heat.
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 VISTARIL vs ACTIDIL, answered by our medical review team.
VISTARIL is a Antihistamine that works by Hydroxyzine is a piperazine derivative antihistamine that acts as a competitive antagonist of histamine H1 receptors, thereby suppressing histamine activity in the subcortical area of the central nervous system. It also has anxiolytic, sedative, antiemetic, and antispasmodic effects.. 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 VISTARIL 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 VISTARIL is: Oral: 50-100 mg 4 times daily; IM: 25-100 mg every 4-6 hours as needed.. 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 VISTARIL 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. VISTARIL is classified as Category C. First trimester: Limited human data; animal studies suggest no major teratogenic risk; fetal harm cannot be ruled out. Second and third trimesters: Hydroxyzine may cause neonatal w. 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.