Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
TYLENOL W/ CODEINE NO. 1 vs ACETAMINOPHEN, CAFFEINE AND DIHYDROCODEINE BITARTRATE
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 via CYP2D6 to morphine, which acts as a μ-opioid receptor agonist. Acetaminophen inhibits cyclooxygenase (COX) enzymes in the CNS, reducing prostaglandin synthesis and modulating pain perception.
Acetaminophen: inhibits cyclooxygenase (COX) activity, reducing prostaglandin synthesis; analgesic and antipyretic. Caffeine: adenosine receptor antagonist; enhances analgesic effect. Dihydrocodeine: mu-opioid receptor agonist; produces analgesia via central opioid receptors.
Mild to moderate pain,Pyrexia
Management of mild to moderate pain where treatment with an opioid is appropriate and for which alternative treatments are inadequate,Off-label: acute pain, chronic pain
Adult: 1-2 tablets (acetaminophen 300 mg/codeine 8 mg per tablet) orally every 4-6 hours as needed; maximum 8 tablets per day. Route: oral. Frequency: every 4-6 hours.
1-2 tablets (each containing acetaminophen 300 mg, caffeine 30 mg, dihydrocodeine bitartrate 20 mg) orally every 4-6 hours as needed for pain; maximum 8 tablets per day.
Acetaminophen: 2-3 hours; Codeine: 2.5-3.5 hours; Morphine (active metabolite): 2-4 hours. Terminal half-life prolonged in hepatic impairment or elderly.
Acetaminophen: 2-3 hours (normal), prolonged in hepatic impairment. Caffeine: 3-6 hours (adults), prolonged in liver disease or with oral contraceptives. Dihydrocodeine: 3.5-6 hours (terminal). Clinical context: q6h dosing interval appropriate; accumulation risk in renal/hepatic impairment.
Acetaminophen is primarily metabolized via glucuronidation and sulfation in the liver, with a minor pathway via CYP2E1 to a toxic metabolite (NAPQI). Codeine is metabolized via CYP2D6 to morphine, via CYP3A4 to norcodeine, and via glucuronidation.
Acetaminophen: primarily hepatic via glucuronidation and sulfation; minor CYP2E1, CYP1A2, CYP3A4. Caffeine: hepatic via CYP1A2. Dihydrocodeine: O-demethylation to dihydromorphine via CYP2D6; also via CYP3A4.
Renal: ~70-80% of codeine as inactive metabolites (codeine-6-glucuronide, norcodeine, morphine) and ~5-10% as unchanged codeine; ~5-15% of acetaminophen as unchanged drug. Biliary/fecal: minimal (<5% for both).
Acetaminophen: renal excretion of metabolites (glucuronide 60%, sulfate 30%, cysteine/mercapturate 8%), <5% unchanged. Caffeine: renal excretion of metabolites (1-methyluric acid, 1-methylxanthine, etc.), <2% unchanged. Dihydrocodeine: renal excretion of metabolites (dihydrocodeine-6-glucuronide, nordihydrocodeine, dihydromorphine), ~20% unchanged. Overall, predominantly renal (≥85%), minor biliary/fecal.
Acetaminophen: 10-25% bound to plasma proteins; Codeine: ~25% bound to plasma proteins.
Acetaminophen: 10-25% (albumin). Caffeine: 25-36% (albumin). Dihydrocodeine: ~20-30% (albumin and α1-acid glycoprotein).
Acetaminophen: ~0.9 L/kg (distributes throughout total body water); Codeine: ~3-6 L/kg (extensively distributed into tissues).
Acetaminophen: 0.7-1.0 L/kg. Caffeine: 0.5-0.8 L/kg. Dihydrocodeine: 1.0-1.5 L/kg. Clinical meaning: moderate distribution, potential for central nervous system penetration.
Acetaminophen: oral bioavailability ~80-85%; Codeine: oral bioavailability ~60-90% (due to first-pass metabolism to morphine).
Acetaminophen: oral 75-85%. Caffeine: oral ~100%. Dihydrocodeine: oral ~20-30% (first-pass metabolism; extended-release formulations have altered bioavailability).
Cr Cl 30-50 m L/min: Administer every 6 hours; Cr Cl <30 m L/min: Avoid due to risk of codeine accumulation and toxicity; hemodialysis: Not recommended.
GFR 30-50 m L/min: administer every 6 hours; GFR 10-30 m L/min: administer every 8 hours; GFR <10 m L/min: administer every 12 hours; avoid in severe impairment due to dihydrocodeine accumulation.
Child-Pugh Class A (mild): No adjustment needed; Child-Pugh Class B (moderate): Reduce dose by 50% and extend interval to every 6-8 hours; Child-Pugh Class C (severe): Contraindicated.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50% or extend interval to every 8 hours; Child-Pugh C: avoid use due to acetaminophen hepatotoxicity and dihydrocodeine accumulation.
Weight-based: Codeine not recommended in pediatric patients <12 years due to risk of respiratory depression; for ages 12-18 years: 1 tablet (acetaminophen 300 mg/codeine 8 mg) orally every 4-6 hours as needed; maximum 4 tablets per day.
Not recommended for children under 12 years due to dihydrocodeine risks; for adolescents 12-18 years: 1 tablet orally every 4-6 hours as needed, maximum 4 tablets per day (weight-based dosing not established).
Start at lowest effective dose (1 tablet) and monitor for respiratory depression and constipation; consider acetaminophen 300 mg/codeine 8 mg every 6 hours; maximum 4 tablets per day.
Initiate with 1 tablet orally every 6 hours; caution due to increased sensitivity to opioids and hepatotoxicity from acetaminophen; maximum 4 tablets per day; monitor renal and hepatic function.
WARNING: RISK OF MEDICATION ERRORS; ADDICTION, ABUSE, AND MISUSE; RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; ULTRA-RAPID METABOLISM OF CODEINE AND OTHER RISK FACTORS FOR LIFE-THREATENING RESPIRATORY DEPRESSION IN CHILDREN; NEONATAL OPIOID WITHDRAWAL SYNDROME; INTERACTION WITH ALCOHOL; RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS; HEPATOTOXICITY.
Risk of addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion of acetaminophen can cause fatal hepatotoxicity; concomitant use with benzodiazepines or CNS depressants may cause profound sedation, respiratory depression, coma, and death; neonatal opioid withdrawal syndrome with prolonged use during pregnancy.
Risk of medication errors (confusion with other products),Addiction, abuse, and misuse,Life-threatening respiratory depression,Accidental ingestion (especially in children),Ultra-rapid metabolism of codeine (CYP2D6 ultra-rapid metabolizers),Neonatal opioid withdrawal syndrome with prolonged use during pregnancy,Hepatotoxicity (acetaminophen overdose),Severe hypotension,Seizures,Adrenal insufficiency,Serotonin syndrome with concomitant serotonergic drugs,Increased risk of severe skin reactions (e.g., SJS/TEN),Interaction with alcohol,Risks from concomitant use with benzodiazepines or other CNS depressants,Impaired mental/physical abilities,Use in children with respiratory conditions,Hepatic or renal impairment
Addiction, abuse, and misuse; respiratory depression; acetaminophen hepatotoxicity; drug interaction with benzodiazepines and CNS depressants; neonatal opioid withdrawal syndrome; risk of serotonin syndrome; severe hypotension; adrenal insufficiency; use in patients with head injury or increased intracranial pressure; seizures; avoid in patients with severe hepatic impairment.
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,Patients with severe hepatic impairment or acute liver disease,Postoperative pain management in children who have had tonsillectomy and/or adenoidectomy,Concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days of such therapy
Hypersensitivity to any component; significant respiratory depression; acute or severe bronchial asthma; GI obstruction; suspected surgical abdomen; concomitant use with MAOIs or within 14 days; severe hepatic impairment.
Avoid alcohol; may increase risk of hepatotoxicity and CNS depression. No specific food restrictions. May be taken with food to reduce gastrointestinal upset.
Avoid alcohol; may increase risk of hepatotoxicity and CNS depression. High-fat meals may delay absorption but do not significantly affect overall exposure. Caffeine-containing foods and beverages may increase stimulant effects.
Acetaminophen: Low teratogenic risk; use at therapeutic doses not associated with increased major malformations. Codeine: First trimester: Risk of malformations unclear; some studies suggest small increased risk of respiratory defects and spina bifida. Third trimester: Prolonged use may cause neonatal opioid withdrawal syndrome (NOWS); high doses near term may cause neonatal respiratory depression. Avoid chronic high doses.
Acetaminophen: Generally considered low risk; no consistent evidence of teratogenicity. Caffeine: High doses (>200 mg/day) associated with increased miscarriage risk; limited data on malformations. Dihydrocodeine: Opioid; first trimester: increased risk of neural tube defects (OR 2.0-2.5); third trimester: risk of neonatal opioid withdrawal syndrome (NOWS). Overall, combination product should be used only if benefit outweighs risks.
Acetaminophen: Compatible; low levels in breast milk (M/P ratio ~0.91). Codeine: Excreted into breast milk; M/P ratio ~2.5. Risk of infant opioid toxicity, especially in ultra-rapid CYP2D6 metabolizers. Use lowest effective dose for shortest duration. Monitor infant for drowsiness, feeding difficulties, respiratory depression.
Acetaminophen: Excreted in breast milk (M/P ratio ~0.9); safe at therapeutic doses. Caffeine: Excreted (M/P ~0.5-0.8); moderate intake (<300 mg/day) generally safe. Dihydrocodeine: Excreted in low levels; however, interindividual variability in metabolism (CYP2D6) may lead to higher morphine concentrations in some infants; risk of neonatal respiratory depression. M/P ratio not well established for dihydrocodeine. Use with caution, monitor infant for sedation and feeding difficulties.
No standard dose adjustment required for acetaminophen. Codeine: Increased clearance in pregnancy may require dose adjustment; however, use lowest effective dose due to unpredictable metabolism. Avoid codeine in pregnancy if possible. Maximum recommended dose: acetaminophen 3000 mg/day; codeine 60 mg/day.
No specific dose adjustments for pregnancy due to lack of pharmacokinetic studies for this combination. However, note: Increased clearance of acetaminophen in pregnancy may require higher doses for analgesia but remains within standard limits. Caffeine clearance decreases in third trimester; consider reducing intake to <200 mg/day. Dihydrocodeine: Increased volume of distribution and clearance in pregnancy; dose may need titration but no established guidelines. Use lowest effective dose for shortest duration.
Contains 300 mg acetaminophen and 15 mg codeine per tablet. Maximum acetaminophen dose 4000 mg/day; avoid combination with other acetaminophen products. Codeine is a prodrug requiring CYP2D6 conversion to morphine; poor metabolizers have reduced analgesia, ultra-rapid metabolizers risk toxicity. Monitor for respiratory depression, especially in children, elderly, or obese. Not recommended in breastfeeding mothers due to risk of infant toxicity.
Dihydrocodeine is a prodrug requiring CYP2D6 metabolism to active metabolites; poor metabolizers may have reduced efficacy while ultrarapid metabolizers risk toxicity. Caffeine potentiates analgesia and may cause insomnia with evening use. Do not exceed 8 tablets per 24 hours due to acetaminophen hepatotoxicity risk. Use with caution in elderly and patients with renal impairment.
Do not exceed 13 tablets per 24 hours due to acetaminophen limit.,Avoid alcohol while taking this medication.,Do not use with any other products containing acetaminophen or codeine.,May cause drowsiness; avoid driving or operating machinery.,Store out of reach of children and dispose of unused medication properly.,Seek medical help if you experience difficulty breathing, severe drowsiness, or signs of allergic reaction.
Take with food if stomach upset occurs.,Avoid alcohol and products containing acetaminophen to prevent liver damage.,Do not exceed 8 tablets in 24 hours.,May cause drowsiness; avoid driving or operating machinery until you know how this medication affects you.,If you have a history of drug dependence, use with caution as dihydrocodeine can be habit-forming.
"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."
"The combination of chlordiazepoxide, a benzodiazepine that enhances GABAergic inhibition, and dihydrocodeine, an opioid agonist primarily at mu-receptors, results in additive central nervous system (CNS) depression. This synergy increases the risk of profound sedation, respiratory depression, coma, and death, particularly in vulnerable populations such as the elderly or those with pre-existing respiratory compromise. Concurrent use also elevates the potential for hypotension and psychomotor impairment, leading to falls or accidents."
"Reserpine depletes catecholamines in the central nervous system and peripheral adrenergic neurons, leading to reduced sympathetic outflow. Dihydrocodeine, an opioid agonist, can cause further central nervous system depression and hypotension. When combined, there is an additive risk of excessive hypotension, bradycardia, and profound sedation, potentially leading to falls or respiratory depression."
"Dihydrocodeine, an opioid analgesic, undergoes O-demethylation primarily via CYP2D6 to form dihydromorphine, which contributes to its analgesic effects. Clemastine, a first-generation antihistamine, is metabolized mainly by CYP2D6 as well. When co-administered, clemastine competitively inhibits CYP2D6, reducing the clearance of dihydrocodeine and decreasing the formation of the active metabolite dihydromorphine. This can lead to diminished analgesic efficacy and potentially increased levels of parent dihydrocodeine, heightening the risk of opioid-related adverse effects such as respiratory depression, sedation, and constipation."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about TYLENOL W/ CODEINE NO. 1 vs ACETAMINOPHEN, CAFFEINE AND DIHYDROCODEINE BITARTRATE, answered by our medical review team.
TYLENOL W/ CODEINE NO. 1 is a Opioid Agonist that works by Codeine is a prodrug that undergoes O-demethylation via CYP2D6 to morphine, which acts as a μ-opioid receptor agonist. Acetaminophen inhibits cyclooxygenase (COX) enzymes in the CNS, reducing prostaglandin synthesis and modulating pain perception.. ACETAMINOPHEN, CAFFEINE AND DIHYDROCODEINE BITARTRATE is a Opioid Agonist that works by Acetaminophen: inhibits cyclooxygenase (COX) activity, reducing prostaglandin synthesis; analgesic and antipyretic. Caffeine: adenosine receptor antagonist; enhances analgesic effect. Dihydrocodeine: mu-opioid receptor agonist; produces analgesia via central opioid receptors.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between TYLENOL W/ CODEINE NO. 1 and ACETAMINOPHEN, CAFFEINE AND DIHYDROCODEINE BITARTRATE 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. 1 is: Adult: 1-2 tablets (acetaminophen 300 mg/codeine 8 mg per tablet) orally every 4-6 hours as needed; maximum 8 tablets per day. Route: oral. Frequency: every 4-6 hours.. The standard adult dose of ACETAMINOPHEN, CAFFEINE AND DIHYDROCODEINE BITARTRATE is: 1-2 tablets (each containing acetaminophen 300 mg, caffeine 30 mg, dihydrocodeine bitartrate 20 mg) orally every 4-6 hours as needed for pain; maximum 8 tablets per 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 TYLENOL W/ CODEINE NO. 1 and ACETAMINOPHEN, CAFFEINE AND DIHYDROCODEINE BITARTRATE. Codeine, a prodrug converted to morphine via CYP2D6, and metyrosine, a tyrosine hydroxylase inhibitor, synergistically depress the central nervous system. Codeine's mu-opioid receptor agonism and metyrosine's reduction of catecholamine synthesis lead to enhanced sedation, respiratory depression, and hypotension. Clinically, patients may experience excessive drowsiness, confusion, or respiratory compromise, particularly at higher doses or in vulnerable populations. Consult your prescriber before combining these medications.
The maternal-fetal safety profiles differ. TYLENOL W/ CODEINE NO. 1 is classified as Category D/X. Acetaminophen: Low teratogenic risk; use at therapeutic doses not associated with increased major malformations. Codeine: First trimester: Risk of malformations unclear; some studi. ACETAMINOPHEN, CAFFEINE AND DIHYDROCODEINE BITARTRATE is classified as Category D/X. Acetaminophen: Generally considered low risk; no consistent evidence of teratogenicity. Caffeine: High doses (>200 mg/day) associated with increased miscarriage risk; limited data . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.