Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
TYLENOL vs ARALEN
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Acetaminophen is a centrally acting analgesic and antipyretic. Its mechanism is not fully understood but involves inhibition of cyclooxygenase (COX) enzymes in the central nervous system, preferentially COX-2, and modulation of descending serotonergic pathways.
Chloroquine, a 4-aminoquinoline, accumulates in acidic organelles such as food vacuoles of malaria parasites, inhibiting heme polymerase and preventing the conversion of toxic heme to hemozoin. It also interferes with DNA synthesis and repair by intercalating into DNA. Additionally, it has immunomodulatory effects via inhibition of Toll-like receptors and cytokine production.
Mild to moderate pain (FDA-approved),Fever (FDA-approved),Osteoarthritis pain (off-label),Patent ductus arteriosus in neonates (off-label IV formulation)
Treatment of uncomplicated malaria caused by susceptible strains of Plasmodium vivax, P. malariae, P. ovale, and P. falciparum,Prophylaxis of malaria in areas with chloroquine-sensitive P. falciparum,Treatment of extraintestinal amebiasis (as amebicide) and giardiasis (off-label),Disease-modifying antirheumatic drug (DMARD) for rheumatoid arthritis and lupus erythematosus (off-label)
650 mg orally every 4-6 hours or 1000 mg orally every 6 hours; maximum 4000 mg per day.
Adults: 500 mg (300 mg base) orally once weekly on the same day each week for prophylaxis of malaria; 1 g (600 mg base) orally initially, followed by 500 mg (300 mg base) at 6, 24, and 48 hours for treatment of acute malaria.
Terminal elimination half-life is 2-3 hours in adults; prolonged to 4-6 hours in neonates and patients with hepatic impairment
Terminal elimination half-life ranges from 30 to 60 days (mean ~45 days) due to extensive tissue binding; clinical context: prolonged half-life allows weekly dosing for malaria prophylaxis.
Primarily hepatic via conjugation with glucuronide (UGT1A1, UGT1A6, UGT1A9) and sulfate (SULT1A1, SULT1A3); minor oxidation by CYP2E1, CYP1A2, and CYP3A4 to N-acetyl-p-benzoquinone imine (NAPQI), which is detoxified by glutathione.
Chloroquine is extensively metabolized in the liver via cytochrome P450 enzymes, primarily CYP2C8 and CYP3A4, to active metabolites such as desethylchloroquine. It has a long elimination half-life of approximately 1-2 months.
Renal excretion of conjugated metabolites (glucuronide and sulfate conjugates) accounts for >90% of elimination; less than 5% excreted unchanged; minor biliary/fecal elimination (<5%)
Primarily renal (approximately 70% as unchanged drug); minor biliary/fecal (about 10-20%).
10-25% bound to plasma proteins (primarily albumin); binding is minimal and not clinically significant
Approximately 50-60% bound; primarily to albumin and alpha-1-acid glycoprotein.
0.8-1.0 L/kg; low Vd indicates limited extravascular distribution, consistent with limited CNS penetration
Very large, 100-200 L/kg; extensive tissue distribution (liver, spleen, kidney, lungs, melanin-containing tissues).
Oral: 60-90% (first-pass hepatic metabolism reduces bioavailability); Rectal: 70-90%; Intravenous: 100%
Oral: 80-90%.
GFR 10-50 m L/min: Administer every 6 hours. GFR <10 m L/min: Administer every 8 hours.
For malaria prophylaxis: No adjustment necessary. For treatment: If Cr Cl < 10 m L/min, reduce dose by 50%.
Child-Pugh A: No adjustment. Child-Pugh B: Reduce dose by 50%; maximum 2000 mg/day. Child-Pugh C: Reduce dose by 75%; maximum 1000 mg/day.
No formal guidelines; use caution in severe hepatic impairment due to potential accumulation. Consider dose reduction in Child-Pugh class C.
10-15 mg/kg orally every 4-6 hours; maximum 75 mg/kg/day or 5 doses per day.
Prophylaxis: 5 mg/kg base (8.3 mg/kg salt) orally once weekly, max 300 mg base. Treatment: 10 mg/kg base (16.7 mg/kg salt) orally initially, followed by 5 mg/kg base at 6, 24, and 48 hours, max 600 mg base on day 1.
Reduce dose by 25-50% in frail elderly; maximum 3000 mg/day due to increased hepatotoxicity risk.
No specific adjustments; consider age-related renal impairment and potential increased risk of QT prolongation. Monitor for cardiac effects.
Acetaminophen has been associated with cases of acute liver failure, at times resulting in liver transplant and death. Most of the cases of liver injury are associated with the use of acetaminophen in doses exceeding 4000 mg per day. The risk of acute liver failure may be higher in individuals with underlying liver disease and in those who consume alcohol chronically.
Retinopathy: Irreversible retinal damage including retinopathy and visual disturbances; risk increases with cumulative dose and duration of use; contraindicated in patients with pre-existing retinopathy; baseline and periodic ophthalmologic exams required.
Hepatotoxicity: Risk increases with doses > 4000 mg/day, chronic alcohol use, or preexisting liver disease.,Severe skin reactions: Stevens-Johnson syndrome, toxic epidermal necrolysis, acute generalized exanthematous pustulosis.,Hypersensitivity: Rare anaphylaxis.
Retinopathy risk with prolonged use; cardiac effects including conduction disorders (e.g., QT prolongation) and cardiomyopathy; exacerbation of psoriasis and porphyria; neuropsychiatric effects (e.g., psychosis, seizures); hematologic toxicity (eg, agranulocytosis, aplastic anemia); hypoglycemia; myopathy; ototoxicity. Use with caution in hepatic or renal impairment, G6PD deficiency, and pregnancy (benefit vs risk).
Hypersensitivity to acetaminophen,Severe hepatic impairment (e.g., active liver disease)
Hypersensitivity to chloroquine or 4-aminoquinolines; pre-existing retinopathy of any etiology; concurrent use with other agents causing retinal toxicity (e.g., hydroxychloroquine, tamoxifen); porphyria; psoriasis (relative, may exacerbate); neuromyopathy (relative); severe hepatic or renal impairment (relative).
No significant food interactions. Alcohol consumption increases risk of hepatotoxicity; avoid concurrent use. High-carbohydrate meals may slightly delay absorption.
Avoid grapefruit juice as it may increase chloroquine levels. No other significant food interactions.
Acetaminophen crosses the placenta. First trimester: no increased risk of major malformations in prospective studies; retrospective studies show possible association with gastroschisis and neural tube defects but confounding by indication is likely. Second and third trimesters: no consistent evidence of adverse fetal effects; chronic high doses may cause maternal hepatotoxicity with secondary fetal effects. Avoid prolonged high-dose therapy.
Pregnancy category C. First trimester: No conclusive evidence of major malformations in human studies, but animal studies show embryotoxicity and fetotoxicity. Second and third trimesters: Risk of sensorineural hearing loss, vestibular damage, and retinal toxicity in the fetus if used for prolonged periods or at high doses; accumulation in fetal ocular tissues reported.
Acetaminophen is excreted into breast milk in low amounts (M/P ratio approximately 0.9; peak milk concentration 10-15 µg/m L after 1g oral dose). Relative infant dose is <2% of maternal weight-adjusted dose. Considered compatible with breastfeeding; monitor infant for rash or drowsiness.
Excreted in breast milk in small amounts (M/P ratio approximately 0.44). American Academy of Pediatrics considers compatible with breastfeeding, but caution is advised in infants with glucose-6-phosphate dehydrogenase deficiency or hemolytic disease. Monitor infant for rash, retinal changes, and hemolysis.
Increased clearance in pregnancy may reduce AUC by 25-30%; recommend standard dosing (500-1000mg every 4-6 hours, max 3000-4000mg/day). No dosage adjustment typically needed. Avoid extended-release formulations due to variable absorption.
No specific dose adjustment recommended for pregnancy; pharmacokinetic changes (increased volume of distribution, decreased plasma concentrations) may require therapeutic drug monitoring, but empirical dose adjustments are not established. Use lowest effective dose and shortest duration.
Acetaminophen has minimal anti-inflammatory effect; prefer NSAIDs for inflammation. Max daily dose 3 g (or 2 g in at-risk patients). N-acetylcysteine is antidote for overdose; administer if serum level above nomogram line. Avoid in severe hepatic impairment. Intravenous formulation available for acute pain. Onset of action 30-60 min, duration 4-6 h. No effect on platelets or GI mucosa.
Chloroquine (Aralen) can cause retinal toxicity; cumulative dose should not exceed 200g. Use with caution in G6PD deficiency. Can prolong QTc interval; avoid with other QTc-prolonging drugs.
Do not exceed 3 g (3000 mg) per day from all products.,Check all over-the-counter medications for acetaminophen content.,Do not take with alcohol or if you have liver disease.,Seek immediate medical attention if overdose is suspected.,May be taken with food if GI upset occurs (though rare).
Take with food to reduce gastrointestinal upset.,Do not exceed prescribed dose; overdose can be fatal.,Report any vision changes immediately; regular eye exams are required.,Avoid alcohol as it may increase risk of liver toxicity.,Inform your doctor if you have a history of heart rhythm problems.
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 TYLENOL vs ARALEN, answered by our medical review team.
TYLENOL is a Analgesic (non-opioid) that works by Acetaminophen is a centrally acting analgesic and antipyretic. Its mechanism is not fully understood but involves inhibition of cyclooxygenase (COX) enzymes in the central nervous system, preferentially COX-2, and modulation of descending serotonergic pathways.. ARALEN is a Antimalarial that works by Chloroquine, a 4-aminoquinoline, accumulates in acidic organelles such as food vacuoles of malaria parasites, inhibiting heme polymerase and preventing the conversion of toxic heme to hemozoin. It also interferes with DNA synthesis and repair by intercalating into DNA. Additionally, it has immunomodulatory effects via inhibition of Toll-like receptors and cytokine production.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between TYLENOL and ARALEN 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 TYLENOL is: 650 mg orally every 4-6 hours or 1000 mg orally every 6 hours; maximum 4000 mg per day.. The standard adult dose of ARALEN is: Adults: 500 mg (300 mg base) orally once weekly on the same day each week for prophylaxis of malaria; 1 g (600 mg base) orally initially, followed by 500 mg (300 mg base) at 6, 24, and 48 hours for treatment of acute malaria.. 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 and ARALEN 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 is classified as Category C. Acetaminophen crosses the placenta. First trimester: no increased risk of major malformations in prospective studies; retrospective studies show possible association with gastrosch. ARALEN is classified as Category C. Pregnancy category C. First trimester: No conclusive evidence of major malformations in human studies, but animal studies show embryotoxicity and fetotoxicity. Second and third tri. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.