Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE vs ACETAMINOPHEN, ASPIRIN, AND CODEINE PHOSPHATE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: June 2026 · OpiCalc Medical Review Team
Acetaminophen: cyclooxygenase (COX) inhibitor, primarily in the CNS, reducing prostaglandin synthesis; analgesic and antipyretic. Oxycodone: mu-opioid receptor agonist, inhibiting ascending pain pathways and altering pain perception.
Acetaminophen: cyclooxygenase (COX) inhibitor, primarily central, analgesic and antipyretic. Aspirin: irreversible COX-1 and COX-2 inhibitor, analgesic, anti-inflammatory, antipyretic, antiplatelet. Codeine: prodrug converted to morphine; mu-opioid receptor agonist.
Management of moderate to moderately severe pain,Acute pain,Chronic pain
Mild to moderate pain,Fever (acetaminophen and aspirin),Inflammatory conditions (aspirin)
1-2 tablets (equivalent to 325-650 mg acetaminophen / 5-10 mg oxycodone) every 4-6 hours as needed for pain; maximum 12 tablets per day (acetaminophen limit 3900 mg/day or lower if hepatic risk).
1-2 tablets (each containing acetaminophen 300 mg, aspirin 300 mg, codeine phosphate 30 mg) orally every 4-6 hours as needed for pain; maximum 8 tablets/day.
Acetaminophen: 2-3 hours (prolonged in hepatic impairment or overdose); Oxycodone: 3-5 hours (immediate-release), 4.5-8 hours (extended-release); Clinical context: Terminal half-life of oxycodone may be prolonged in elderly or patients with renal/hepatic impairment.
Acetaminophen: 2-3 hours (terminal). Aspirin: 15-30 minutes (parent drug); salicylate: 2-3 hours at low doses, 15-30 hours at high doses due to saturable metabolism. Codeine: 2.5-4 hours. Clinical context: Prolonged half-life of salicylate at high doses increases risk of toxicity; hepatic impairment prolongs acetaminophen and codeine half-lives.
Acetaminophen: primarily hepatic via glucuronidation (UGT1A1, UGT1A6, UGT1A9), sulfation (SULT1A1), and minor CYP450 (CYP2E1, CYP3A4) to toxic NAPQI. Oxycodone: hepatic via CYP3A4 (major) and CYP2D6 (minor) to active metabolites (noroxycodone, oxymorphone).
Acetaminophen: hepatic via CYP2E1, CYP1A2, CYP3A4; glucuronidation and sulfation; NAPQI formation. Aspirin: hepatic hydrolysis to salicylate; conjugation with glycine and glucuronic acid. Codeine: hepatic via CYP2D6 to morphine (active); also via CYP3A4 to norcodeine.
Acetaminophen: renal excretion of metabolites (glucuronide 45-55%, sulfate 20-30%, cysteine and mercapturate conjugates 5-10%) and unchanged drug (<5%); Oxycodone: renal excretion of unchanged drug (approximately 10-19%) and metabolites (noroxycodone, oxymorphone, and their glucuronides) (total renal elimination ~60-87%); fecal elimination of Oxycodone is minimal (<10%).
Acetaminophen: renal excretion of metabolites (glucuronide and sulfate conjugates, ~85-90%), minor parent drug (<5%). Aspirin: renal excretion of salicylate and its metabolites (salicyluric acid, glucuronides, gentisic acid), dose-dependent; at therapeutic doses, ~50-80% as free salicylate and conjugates. Codeine: renal excretion of free and conjugated codeine (about 90%) and metabolites (morphine, norcodeine).
Acetaminophen: 20-30% (albumin); Oxycodone: 45-50% (albumin).
Acetaminophen: 10-25% (albumin). Aspirin: 50-80% (albumin), dose-dependent; salicylate: 75-90% (albumin). Codeine: ~7% (albumin).
Acetaminophen: 0.9-1.0 L/kg (suggests distribution into total body water); Oxycodone: 2.6-4.0 L/kg (suggests extensive tissue distribution).
Acetaminophen: 0.9-1.0 L/kg (large distribution including liver). Aspirin: 0.15-0.2 L/kg (low Vd, confined to plasma and extracellular fluid); salicylate: 0.2-0.3 L/kg. Codeine: 3-6 L/kg (extensive tissue distribution). Clinical meaning: Large Vd for codeine suggests extensive tissue binding; aspirin Vd is small, consistent with limited extravascular distribution.
Acetaminophen: Oral 85-90%; Oxycodone: Oral 60-87% (first-pass metabolism), Rectal (oxycodone suppository) ~60-80%.
Oral: Acetaminophen: 85-95%. Aspirin: 40-60% (due to first-pass hydrolysis to salicylate). Codeine: ~50% due to first-pass metabolism.
e GFR 30-60 m L/min: start with 50% of usual dose, increase cautiously; e GFR <30 m L/min: start with 25% of usual dose, extend dosing interval to every 8-12 hours; avoid in dialysis due to oxycodone accumulation.
GFR 30-59 m L/min: Administer every 6 hours; maximum 6 tablets/day. GFR 15-29 m L/min: Administer every 12 hours; maximum 4 tablets/day. GFR <15 m L/min: Not recommended due to accumulation of codeine metabolites.
Child-Pugh A: no adjustment; Child-Pugh B: start with 50% of usual dose, maximum acetaminophen 2000 mg/day; Child-Pugh C: contraindicated.
Child-Pugh Class A: No adjustment. Child-Pugh Class B: Reduce dose by 50% and extend interval to every 6 hours; maximum 4 tablets/day. Child-Pugh Class C: Contraindicated.
Weight-based: oxycodone 0.05-0.15 mg/kg/dose (max 5 mg/dose) with acetaminophen 10-15 mg/kg/dose every 4-6 hours; maximum acetaminophen 75 mg/kg/day (not to exceed 4000 mg/day).
Not recommended for children <12 years due to aspirin risk of Reye syndrome. For children ≥12 years: Dose based on codeine component (0.5-1 mg/kg/dose) with maximum acetaminophen 75 mg/kg/day and aspirin 100 mg/kg/day. Typical: 1 tablet (acetaminophen 300 mg/aspirin 300 mg/codeine 30 mg) every 4-6 hours as needed; max 4 tablets/day.
Start with lowest dose (e.g., half of adult dose), titrate slowly; avoid in patients with impaired renal/hepatic function or those at risk for falls; monitor for respiratory depression and constipation.
Start with lowest effective dose (e.g., 1 tablet every 6 hours); monitor renal and hepatic function; maximum 6 tablets/day due to increased sensitivity and risk of adverse effects.
Risk of addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion of acetaminophen may cause hepatotoxicity; neonatal opioid withdrawal syndrome; CYP3A4 interaction with benzodiazepines or other CNS depressants.
Risk of medication errors: confusion between different strengths and concentrations of acetaminophen can result in accidental overdose and fatal hepatotoxicity. Aspirin use in children and teenagers with viral infections is associated with Reye's syndrome.
Addiction, abuse, misuse; respiratory depression; accidental exposure; neonatal opioid withdrawal syndrome; hepatotoxicity (acetaminophen); interactions with CNS depressants; elderly or debilitated patients; renal impairment; severe hypotension; adrenal insufficiency; use in patients with head injury.
Hepatotoxicity (acetaminophen dose >4 g/day), Reye's syndrome (aspirin in children), respiratory depression (codeine), tolerance/dependence, bleeding risk (aspirin), GI toxicity, renal impairment, hypersensitivity reactions.
Hypersensitivity to acetaminophen or oxycodone; significant respiratory depression; acute or severe bronchial asthma; GI obstruction (e.g., paralytic ileus); severe hepatic impairment; concurrent use with MAOIs or within 14 days.
Hypersensitivity to any component, active peptic ulcer disease, bleeding disorders, severe hepatic impairment, severe respiratory depression, children with viral illness (aspirin), pregnancy (third trimester for aspirin, codeine cautious).
Avoid alcohol. Grapefruit juice may increase oxycodone levels; limit or avoid grapefruit products. High-fat meals may delay absorption of oxycodone. Maintain adequate hydration to prevent constipation.
Avoid alcohol due to increased risk of acetaminophen hepatotoxicity and aspirin-induced GI bleeding. Avoid large amounts of caffeine or high-tyramine foods (e.g., aged cheeses, cured meats) as they may affect CYP2D6 metabolism of codeine.
Acetaminophen: Generally considered low risk; no consistent association with major malformations. Oxycodone: First trimester: No increased risk of major malformations in human studies. Second and third trimesters: Risk of neonatal opioid withdrawal syndrome (NOWS) with chronic use; respiratory depression at delivery. No specific human data for combination; extrapolated from individual components.
Acetaminophen: Generally considered low risk; association with ASD and ADHD with prolonged use not fully established. Aspirin: First trimester: possible increased risk of gastroschisis; second trimester: relatively safe; third trimester: risk of premature closure of ductus arteriosus, oligohydramnios, and increased peripartum hemorrhage. Codeine: First trimester: possible neural tube defects; second and third trimesters: risk of respiratory depression, withdrawal in neonate with chronic use; neonatal opioid withdrawal syndrome (NOWS) possible.
Acetaminophen: Compatible; M/P ratio ~1.0 (low transfer). Oxycodone: Low levels in milk; M/P ratio ~3.6 (relative infant dose 1.7–6.3% of maternal weight-adjusted dose). Monitor infant for drowsiness, respiratory depression. Use lowest effective dose, shortest duration.
Acetaminophen: M/P ratio approximately 0.91-1.42; considered safe. Aspirin: M/P ratio 0.08-0.15; high doses may cause Reye's syndrome; avoid or use low doses. Codeine: M/P ratio about 2.5; variable metabolism; risk of CNS depression in infant; avoid due to potential for toxicity in CYP2D6 ultrarapid metabolizers.
Acetaminophen: No dose adjustment needed; use lowest effective dose. Oxycodone: Pharmacokinetic changes in pregnancy include increased clearance (due to enhanced hepatic metabolism and renal blood flow) and increased volume of distribution, potentially reducing plasma concentrations. Dose may need to be increased (monitor for efficacy and avoid withdrawal); however, use lowest effective dose to minimize neonatal risks. Consider non-opioid alternatives.
Acetaminophen: No dose adjustment needed. Aspirin: Avoid in third trimester; use lowest effective dose if necessary. Codeine: Avoid in pregnancy; if used, lowest effective dose for shortest duration; caution for CYP2D6 polymorphism. Pharmacokinetic changes: Increased clearance of codeine during pregnancy may require higher doses but risk outweighs benefit.
Monitor for acetaminophen hepatotoxicity; maximum daily acetaminophen intake should not exceed 4000 mg. Oxycodone has high abuse potential; consider prescribing naloxone for patients at risk of opioid overdose. Avoid concurrent use of other CNS depressants. Use with caution in elderly or renally impaired patients.
Combination analgesic with acetaminophen (hepatotoxic at high doses), aspirin (antiplatelet, GI irritant, contraindicated in children <12 due to Reye's syndrome), and codeine (prodrug to morphine via CYP2D6; efficacy depends on CYP2D6 phenotype; risk of CNS/respiratory depression). Avoid in severe hepatic/renal impairment, active peptic ulcer, bleeding disorders, or concomitant use of other CNS depressants. Maximum acetaminophen dose from all sources: 4 g/day.
Do not exceed 4000 mg of acetaminophen per day from all sources.,This medication can cause drowsiness; avoid driving or operating machinery until you know how it affects you.,Do not consume alcohol while taking this medication.,Take exactly as prescribed; do not crush, chew, or break extended-release tablets.,Store securely out of reach of children and dispose of unused medication properly.,Seek emergency medical attention if you experience difficulty breathing, severe drowsiness, or signs of an allergic reaction.
Do not exceed recommended dose; acetaminophen overdosage can cause serious liver damage.,Do not take with other products containing acetaminophen or aspirin.,Avoid alcohol while taking this medication to reduce risk of liver toxicity and GI bleeding.,This product contains aspirin; do not give to children/teenagers with chickenpox or flu-like symptoms to avoid Reye's syndrome.,May cause drowsiness; do not drive or operate machinery until you know how you react.,Codeine is a narcotic pain reliever with abuse potential; use exactly as prescribed.,Seek medical attention if you experience signs of allergic reaction (rash, difficulty breathing) or bleeding (black/tarry stools, unusual bruising).
"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."
"Pirenzepine, a selective M1 muscarinic antagonist, reduces gastrointestinal motility and secretions, while codeine, an opioid agonist, also decreases gastrointestinal motility via mu-opioid receptors. Concurrent use leads to additive anticholinergic and opioid effects, resulting in enhanced risk of severe constipation, paralytic ileus, and central nervous system depression. Clinically, patients may experience exacerbated sedation, respiratory depression, and urinary retention."
"Ropinirole, a non-ergoline dopamine agonist used in Parkinson's disease and restless legs syndrome, may reduce the analgesic efficacy of codeine. This is likely due to pharmacodynamic antagonism at central dopamine and opioid receptors, as well as potential pharmacokinetic interactions that decrease the conversion of codeine to its active metabolite morphine via CYP2D6 inhibition by ropinirole. The resultant blunted opioid response can lead to inadequate pain control, necessitating dose adjustment or alternative therapy."
"Vemurafenib induces CYP3A4, significantly reducing the plasma concentrations of codeine, which is metabolized via CYP3A4 to its active metabolite morphine. This may diminish codeine's analgesic efficacy, potentially leading to inadequate pain control. Additionally, reduced formation of morphine may lower the risk of opioid-related adverse effects."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE vs ACETAMINOPHEN, ASPIRIN, AND CODEINE PHOSPHATE, answered by our medical review team.
ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE is a Opioid Agonist that works by Acetaminophen: cyclooxygenase (COX) inhibitor, primarily in the CNS, reducing prostaglandin synthesis; analgesic and antipyretic. Oxycodone: mu-opioid receptor agonist, inhibiting ascending pain pathways and altering pain perception.. ACETAMINOPHEN, ASPIRIN, AND CODEINE PHOSPHATE is a Opioid Agonist that works by Acetaminophen: cyclooxygenase (COX) inhibitor, primarily central, analgesic and antipyretic. Aspirin: irreversible COX-1 and COX-2 inhibitor, analgesic, anti-inflammatory, antipyretic, antiplatelet. Codeine: prodrug converted to morphine; mu-opioid receptor agonist.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE and ACETAMINOPHEN, ASPIRIN, AND CODEINE PHOSPHATE depend on the specific clinical indication. These are both Opioid Agonist agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE is: 1-2 tablets (equivalent to 325-650 mg acetaminophen / 5-10 mg oxycodone) every 4-6 hours as needed for pain; maximum 12 tablets per day (acetaminophen limit 3900 mg/day or lower if hepatic risk).. The standard adult dose of ACETAMINOPHEN, ASPIRIN, AND CODEINE PHOSPHATE is: 1-2 tablets (each containing acetaminophen 300 mg, aspirin 300 mg, codeine phosphate 30 mg) orally every 4-6 hours as needed for pain; maximum 8 tablets/day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
A moderate-severity drug interaction has been identified when combining ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE and ACETAMINOPHEN, ASPIRIN, AND CODEINE PHOSPHATE. The risk or severity of adverse effects can be increased when Codeine is combined with Oxycodone. Consult your prescriber before combining these medications.
The maternal-fetal safety profiles differ. ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE is classified as Category D/X. Acetaminophen: Generally considered low risk; no consistent association with major malformations. Oxycodone: First trimester: No increased risk of major malformations in human stud. ACETAMINOPHEN, ASPIRIN, AND CODEINE PHOSPHATE is classified as Category D/X. Acetaminophen: Generally considered low risk; association with ASD and ADHD with prolonged use not fully established. Aspirin: First trimester: possible increased risk of gastrosch. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.