Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
VISTARIL vs OXYCODONE AND ASPIRIN (HALF-STRENGTH)
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.
Oxycodone is a full opioid agonist with relative selectivity for the mu-opioid receptor, resulting in analgesia through supraspinal and spinal pathways. Aspirin irreversibly acetylates cyclooxygenase-1 and -2 (COX-1/2), inhibiting prostaglandin synthesis and providing anti-inflammatory and analgesic effects.
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)
Moderate to moderately severe pain (when combination therapy is appropriate),Off-label: acute pain, chronic pain
Oral: 50-100 mg 4 times daily; IM: 25-100 mg every 4-6 hours as needed.
Adults: One to two tablets (325 mg aspirin/2.5 mg oxycodone per tablet) orally every 6 hours as needed for pain. Maximum dose: 12 tablets per day.
Terminal elimination half-life: 20-25 hours in adults; prolonged in hepatic impairment or elderly; steady-state achieved in ~4-5 days.
Aspirin: 2-3 hours for low doses, 15-30 hours for anti-inflammatory doses; increased half-life with dose due to saturable metabolism. Oxycodone: Immediate release: 3-4 hours; controlled release: 4.5-5 hours with biphasic absorption.
Primarily hepatic via CYP3A4 and CYP2D6; major metabolites include cetirizine.
Oxycodone is extensively metabolized in the liver via CYP3A4 (N-demethylation to noroxycodone) and CYP2D6 (O-demethylation to oxymorphone). Aspirin is rapidly hydrolyzed to salicylic acid by esterases in the liver and plasma; salicylic acid is conjugated primarily with glycine (salicyluric acid) and glucuronic acid.
Primarily hepatic metabolism; <1% excreted unchanged in urine; biliary/fecal elimination of metabolites accounts for approximately 50-60% of total clearance.
Aspirin: Renal (primarily as salicyluric acid, salicyl glucuronides, and free salicylate); 10% excreted as unchanged salicylate. Oxycodone: Renal (primarily as noroxycodone, oxymorphone, and conjugates); approximately 87% eliminated in urine, 10-14% in feces.
Highly protein-bound: approximately 89-93%, primarily to albumin.
Aspirin: 80-90% (primarily to albumin, saturable). Oxycodone: 38-45% (primarily to albumin).
Volume of distribution: 7-10 L/kg, indicating extensive tissue distribution.
Aspirin: 0.15-0.2 L/kg. Oxycodone: 2.0-3.7 L/kg; extensive tissue distribution.
Oral: incomplete bioavailability due to first-pass metabolism, estimated at 40-60%; IM: nearly complete (85-100%).
Oral: Aspirin: 80-100% (first-pass hydrolysis to salicylate). Oxycodone: 60-87% (oral); rectal: similar to oral; intravenous: 100%.
No specific adjustment; use with caution in severe renal impairment due to potential accumulation of metabolites.
For GFR 10-50 m L/min: Administer 75% of usual dose at extended intervals (every 8-12 hours). For GFR <10 m L/min: Avoid use due to risk of aspirin accumulation and oxycodone toxicity.
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 necessary. Child-Pugh Class B: Initiate at 50-75% of usual dose and titrate cautiously. Child-Pugh Class C: Avoid use due to risk of oxycodone accumulation and aspirin-induced bleeding.
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.
Not recommended for pediatric use due to risk of Reye's syndrome from aspirin and lack of safety data for oxycodone in children <18 years.
Start at lower end of dosing range (e.g., 25 mg oral 3-4 times daily); monitor for sedation and anticholinergic effects.
Initiate at the low end of dosing range (e.g., one tablet every 6 hours) due to increased sensitivity to opioid effects and risk of aspirin-induced gastrointestinal bleeding. Titrate slowly and monitor renal function.
No FDA black box warning.
Addiction, abuse, and misuse risk; life-threatening respiratory depression; accidental ingestion (especially in children) can be fatal; neonatal opioid withdrawal syndrome with prolonged use during pregnancy; cytochrome P450 3A4 interaction with concomitant CNS depressants; risk of Reye syndrome (aspirin) in children and teenagers with viral illnesses.
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
Respiratory depression; drug dependence, abuse, and addiction; CNS depression (additive with other CNS depressants); head injury and increased intracranial pressure; hypotension; seizure disorders; biliary tract disease; impaired renal or hepatic function; history of gastrointestinal bleeding (aspirin); bleeding disorders (aspirin); concurrent use with anticoagulants; Reye syndrome; hypersensitivity to aspirin or NSAIDs; pregnant women (prolonged use may cause neonatal withdrawal).
Hypersensitivity to hydroxyzine or any component,Early pregnancy (first trimester),Porphyria,Breastfeeding (use caution)
Hypersensitivity to oxycodone, aspirin, or any component; severe respiratory depression; acute or severe bronchial asthma; known or suspected gastrointestinal obstruction; Reye syndrome (in children/teenagers with viral illness) (aspirin); pregnancy (prolonged use or high doses near term); breastfeeding (oxycodone); severe bleeding disorders (aspirin); concomitant use with monoamine oxidase inhibitors (MAOIs) or within 14 days of such therapy.
Alcohol increases sedation and CNS depression; avoid concurrent use. No significant food interactions, but take with food if GI upset occurs.
Avoid alcohol; may increase risk of liver damage (not applicable) and gastric bleeding. Avoid high-tyramine foods (e.g., aged cheeses, cured meats) if taking MAOIs (unlikely but caution). Take with food to minimize GI irritation.
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.
Pregnancy Category D (oxycodone) and Category D (aspirin) prior to 2015 reclassification; current FDA labeling advises avoidance in pregnancy. First trimester: Aspirin associated with increased risk of neural tube defects and gastroschisis; oxycodone may cause neural tube defects. Second trimester: Aspirin may impair fetal renal function; oxycodone risk persists. Third trimester: Aspirin increases risk of premature closure of ductus arteriosus, oligohydramnios, and periventricular hemorrhage; oxycodone may cause neonatal withdrawal syndrome. Chronic use may lead to neonatal abstinence syndrome.
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.
Oxycodone: M/P ratio approximately 0.5; low levels in milk (0.3-6.9% of maternal weight-adjusted dose), but risk of neonatal sedation and withdrawal. Aspirin: Excreted in milk; M/P ratio ~0.03-0.1; risk of Reye's syndrome with high doses. Both drugs generally contraindicated during breastfeeding due to potential adverse effects in infants.
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.
Oxycodone: Increased clearance and volume of distribution in pregnancy may require higher doses for analgesia; dose adjustment should be individualized. Aspirin: No pharmacokinetic adjustments recommended; however, due to teratogenicity and fetal risks, use is contraindicated in pregnancy, especially during third trimester. Half-strength formulation not specifically studied; dosage should be based on oxycodone component (typically 2.25 mg) and aspirin component (325 mg) with caution.
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.
Monitor for respiratory depression, especially in elderly or debilitated patients. Avoid in patients with severe asthma or COPD. Assess renal function before use, as aspirin can worsen renal impairment. The half-strength formulation contains 325 mg aspirin and 2.25 mg oxycodone HCl per tablet.
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.
Take with food or milk to reduce stomach upset.,Do not exceed recommended dose; risk of liver damage with acetaminophen-containing products (not applicable here), but aspirin can cause gastrointestinal bleeding.,Avoid alcohol while taking this medication.,Do not crush or chew extended-release tablets (this formulation is immediate-release; advise to swallow whole).,May cause drowsiness or dizziness; avoid driving until you know how the medication affects you.,Seek medical help if you experience signs of allergic reaction (rash, difficulty breathing) or signs of bleeding (black stools, vomiting blood).
No interactions on record
"Phenobarbital, a potent inducer of cytochrome P450 (CYP) enzymes, particularly CYP3A4 and CYP2D6, significantly increases the hepatic metabolism of oxycodone, a prodrug that requires CYP3A4-mediated N-demethylation to noroxycodone and CYP2D6-mediated O-demethylation to oxymorphone for its analgesic effects. This induction reduces the systemic exposure and peak plasma concentration of active oxycodone and its active metabolite oxymorphone, leading to diminished analgesic efficacy and potential opioid withdrawal symptoms in patients on chronic opioid therapy. Clinically, patients may require substantially higher doses of oxycodone to achieve pain relief, increasing the risk of dose-related adverse effects if the interaction is not recognized."
"The co-administration of oxycodone, a mu-opioid receptor agonist, and gamma-hydroxybutyric acid (GHB), a central nervous system depressant with activity at GABA-B and GHB receptors, results in additive or synergistic respiratory depression and CNS depression. This interaction potentiates the risk of severe hypoventilation, coma, and fatal overdose, especially in non-tolerant users or at therapeutic doses. The combined sedation also increases the likelihood of hypotension, bradycardia, and impaired psychomotor function, necessitating extreme caution."
"The coadministration of oxycodone, a mu-opioid receptor agonist with central nervous system (CNS) depressant effects, and perampanel, a noncompetitive AMPA receptor antagonist that also causes CNS depression, produces additive sedative and respiratory depressant effects. This synergy increases the risk of excessive sedation, impaired cognitive function, and potentially life-threatening respiratory depression. Patients may experience profound somnolence, confusion, and an increased fall risk, necessitating dose adjustments or avoidance."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about VISTARIL vs OXYCODONE AND ASPIRIN (HALF-STRENGTH), 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.. OXYCODONE AND ASPIRIN (HALF-STRENGTH) is a Opioid Agonist that works by Oxycodone is a full opioid agonist with relative selectivity for the mu-opioid receptor, resulting in analgesia through supraspinal and spinal pathways. Aspirin irreversibly acetylates cyclooxygenase-1 and -2 (COX-1/2), inhibiting prostaglandin synthesis and providing anti-inflammatory and analgesic effects.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between VISTARIL and OXYCODONE AND ASPIRIN (HALF-STRENGTH) depend on the specific clinical indication. These are agents from distinct pharmacological classes 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 OXYCODONE AND ASPIRIN (HALF-STRENGTH) is: Adults: One to two tablets (325 mg aspirin/2.5 mg oxycodone per tablet) orally every 6 hours as needed for pain. Maximum dose: 12 tablets 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 OXYCODONE AND ASPIRIN (HALF-STRENGTH) 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. OXYCODONE AND ASPIRIN (HALF-STRENGTH) is classified as Category D/X. Pregnancy Category D (oxycodone) and Category D (aspirin) prior to 2015 reclassification; current FDA labeling advises avoidance in pregnancy. First trimester: Aspirin associated w. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.