Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
TYLENOL W/ CODEINE NO. 4 vs ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Codeine is a prodrug that undergoes O-demethylation by CYP2D6 to morphine, which acts as a μ-opioid receptor agonist, inhibiting adenylate cyclase and modulating neurotransmitter release in the CNS. Acetaminophen inhibits cyclooxygenase (COX) enzymes, primarily in the CNS, reducing prostaglandin synthesis and modulating pain perception.
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.
Management of mild to moderate pain where an opioid analgesic is needed
Management of moderate to moderately severe pain,Acute pain,Chronic pain
One or 2 tablets (acetaminophen 300 mg-codeine 60 mg per tablet) orally every 4 hours as needed for pain; maximum 12 tablets per day.
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).
Codeine: Terminal half-life of 2.5-3.5 hours; however, its active metabolite morphine has a half-life of 1.5-2 hours, and morphine-6-glucuronide (M6G) has a half-life of 2-4 hours. Acetaminophen: Terminal half-life of 2-3 hours in adults; prolonged in hepatic impairment (up to 4-5 hours) or overdose (4-12 hours). Clinically, duration of analgesic effect is approximately 4-6 hours.
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.
Codeine: metabolized by CYP2D6 to morphine (active), CYP3A4 to norcodeine, and glucuronidation. Acetaminophen: extensively metabolized in the liver via conjugation (glucuronidation, sulfation) and minor oxidation by CYP2E1 to N-acetyl-p-benzoquinone imine (NAPQI), which is detoxified by glutathione.
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).
Codeine and its metabolites (including morphine, morphine-6-glucuronide, and norcodeine) are primarily excreted renally. Approximately 90% of a codeine dose is excreted in urine within 24 hours, with 5-15% as free codeine, 5-13% as free morphine, 40-60% as codeine conjugates, and 5-10% as morphine conjugates. Fecal excretion accounts for less than 5%. Acetaminophen is primarily metabolized in the liver to glucuronide and sulfate conjugates; about 85% of a dose is excreted renally as conjugates within 24 hours, with 2-4% excreted unchanged. Minor biliary/fecal elimination occurs for both drugs.
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%).
Codeine: Approximately 20-40% bound to plasma proteins (primarily albumin). Morphine: 20-35% bound. Acetaminophen: 10-25% bound to albumin. Binding is minimal and generally not clinically significant.
Acetaminophen: 20-30% (albumin); Oxycodone: 45-50% (albumin).
Codeine: Vd approximately 3-4 L/kg (range 2.5-5 L/kg). Acetaminophen: Vd approximately 0.9 L/kg (range 0.7-1.0 L/kg). Codeine's larger Vd indicates extensive tissue distribution; acetaminophen distributes evenly throughout body fluids.
Acetaminophen: 0.9-1.0 L/kg (suggests distribution into total body water); Oxycodone: 2.6-4.0 L/kg (suggests extensive tissue distribution).
Oral: Codeine bioavailability is approximately 50-60% (first-pass metabolism). Acetaminophen bioavailability is 70-90% (absorbed rapidly from GI tract; first-pass metabolism minimal). Rectal bioavailability of acetaminophen is approximately 80-90% of oral.
Acetaminophen: Oral 85-90%; Oxycodone: Oral 60-87% (first-pass metabolism), Rectal (oxycodone suppository) ~60-80%.
e GFR 30-50 m L/min: use with caution, reduce dose by 25%. e GFR <30 m L/min: not recommended due to risk of accumulation and respiratory depression.
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.
Child-Pugh class A: caution, maximum 2 tablets per dose; class B or C: contraindicated.
Child-Pugh A: no adjustment; Child-Pugh B: start with 50% of usual dose, maximum acetaminophen 2000 mg/day; Child-Pugh C: contraindicated.
Not recommended for children under 12 years. For ages 12-18: weight-based codeine dosing 0.5-1 mg/kg/dose every 4-6 hours (max 60 mg/dose); acetaminophen 15 mg/kg/dose every 4-6 hours (max 75 mg/kg/day). Use lowest effective dose.
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).
Initiate at half the adult dose (1 tablet) every 4 hours due to increased sensitivity to opioids and acetaminophen hepatotoxicity; maximum 8 tablets per day. Monitor renal and hepatic function closely.
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.
WARNING: ADDICTION, ABUSE, AND MISUSE; LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; ULTRA-RAPID METABOLISM OF CODEINE AND OTHER RISK FACTORS FOR LIFE-THREATENING RESPIRATORY DEPRESSION IN CHILDREN; NEONATAL OPIOID WITHDRAWAL SYNDROME; HEPATOTOXICITY; INTERACTION WITH ALCOHOL; RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS; RISK OF MEDICATION ERRORS.
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 addiction, abuse, and misuse,Life-threatening respiratory depression, especially in patients with compromised respiratory function,Accidental ingestion of even one dose, especially by children, can be fatal,Ultra-rapid metabolism of codeine to morphine due to CYP2D6 polymorphism leading to toxicity,Neonatal opioid withdrawal syndrome with prolonged use during pregnancy,Hepatotoxicity due to acetaminophen, especially with doses >4000 mg/day or with concurrent alcohol use,Interaction with alcohol and other CNS depressants,Concomitant use with MAOIs or within 14 days is contraindicated,Avoid use in children <12 years of age and in children <18 years after tonsillectomy/adenoidectomy
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.
Hypersensitivity to codeine, acetaminophen, or any component,Significant respiratory depression,Acute or severe bronchial asthma in an unmonitored setting or without resuscitative equipment,Known or suspected gastrointestinal obstruction, including paralytic ileus,Concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days,Children <12 years of age,Children <18 years of age after tonsillectomy/adenoidectomy
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.
Avoid alcohol and foods containing alcohol (e.g., desserts, sauces) due to increased risk of hepatotoxicity and CNS depression. No specific food restrictions otherwise.
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.
Pregnancy Category C prior to 2015; current data insufficient for definitive risk. Acetaminophen: no consistent evidence of major malformations; codeine: opioid use in first trimester associated with small increased risk of neural tube defects (OR 1.1-1.3); third trimester use may cause neonatal opioid withdrawal syndrome (NOWS) and respiratory depression at delivery.
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 is compatible (low levels in milk). Codeine is present in milk; M/P ratio approximately 2:1 (morphine). Caution: ultra-rapid CYP2D6 metabolizers may produce high morphine levels leading to infant toxicity. Use lowest effective dose for shortest duration; monitor infant for drowsiness, difficulty breathing.
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.
No specific dose adjustment recommended for acetaminophen; codeine pharmacokinetics altered in pregnancy (increased clearance, decreased half-life). Avoid codeine in pregnancy if possible; if used, lowest effective dose for shortest duration. Consider alternative analgesics (e.g., acetaminophen alone). Postpartum: resume standard dosing.
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.
Each tablet contains acetaminophen 300 mg and codeine phosphate 60 mg. Maximum acetaminophen dose: 4 g/day; avoid other acetaminophen-containing products. Codeine is a prodrug; CYP2D6 poor metabolizers may have reduced efficacy, while ultra-rapid metabolizers risk toxicity. Monitor for respiratory depression, especially in opioid-naive patients. Use with caution in patients with liver impairment or G6PD deficiency.
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.
Do not exceed 12 tablets in 24 hours due to acetaminophen content.,Avoid alcohol while taking this medication.,This drug may cause drowsiness; do not drive or operate machinery until you know how it affects you.,Contact your doctor if you experience signs of allergic reaction (rash, difficulty breathing) or liver injury (yellowing of skin/eyes, dark urine).,Do not take with other products containing acetaminophen (e.g., Tylenol, cold medicines).,Codeine can be habit-forming; use only as prescribed.,Women who are breastfeeding should consult their doctor; codeine can pass into breast milk.
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.
"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."
"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 TYLENOL W/ CODEINE NO. 4 vs ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE, answered by our medical review team.
TYLENOL W/ CODEINE NO. 4 is a Opioid Agonist that works by Codeine is a prodrug that undergoes O-demethylation by CYP2D6 to morphine, which acts as a μ-opioid receptor agonist, inhibiting adenylate cyclase and modulating neurotransmitter release in the CNS. Acetaminophen inhibits cyclooxygenase (COX) enzymes, primarily in the CNS, reducing prostaglandin synthesis and modulating pain perception.. 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.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between TYLENOL W/ CODEINE NO. 4 and ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE 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 TYLENOL W/ CODEINE NO. 4 is: One or 2 tablets (acetaminophen 300 mg-codeine 60 mg per tablet) orally every 4 hours as needed for pain; maximum 12 tablets per day.. 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).. 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 TYLENOL W/ CODEINE NO. 4 and ACETAMINOPHEN; OXYCODONE HYDROCHLORIDE 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. TYLENOL W/ CODEINE NO. 4 is classified as Category D/X. Pregnancy Category C prior to 2015; current data insufficient for definitive risk. Acetaminophen: no consistent evidence of major malformations; codeine: opioid use in first trimes. 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. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.