Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ADVIL PM vs 8-HOUR BAYER
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis. Diphenhydramine is a first-generation antihistamine that antagonizes histamine H1 receptors, causing sedation.
Irreversibly acetylates cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), inhibiting prostaglandin and thromboxane A2 synthesis, leading to analgesic, antipyretic, anti-inflammatory, and antiplatelet effects.
Temporary relief of occasional sleeplessness associated with minor aches and pains
Relief of pain, fever, and inflammation,Reduction of risk of myocardial infarction in patients with previous MI or unstable angina,Prevention of recurrent ischemic stroke or transient ischemic attack
Two caplets (ibuprofen 200 mg, diphenhydramine citrate 38 mg) orally at bedtime as needed for insomnia. Maximum: 2 caplets in 24 hours.
325-650 mg every 8 hours for pain/fever; 81-325 mg daily for cardiovascular prophylaxis.
Ibuprofen: 2-4 hours (terminal); clinical context: steady state achieved in 1 day, not affected by renal impairment. Diphenhydramine: 4-8 hours (terminal); clinical context: prolonged in hepatic impairment.
15-20 hours (terminal elimination half-life) for salicylate at therapeutic concentrations; prolonged to 20-30 hours at high doses due to saturation of hepatic metabolism (zero-order kinetics).
Ibuprofen is primarily metabolized via hepatic oxidation by CYP2C9. Diphenhydramine is metabolized via hepatic N-demethylation and oxidation, primarily by CYP2D6.
Hepatic hydrolysis by esterases to salicylic acid, which is primarily conjugated in the liver via glucuronidation and glycine conjugation (salicyluric acid), with minor oxidation by cytochrome P450 (CYP2C9) to gentisic acid.
Ibuprofen: Renal (90% as metabolites and conjugates, <10% unchanged); Diphenhydramine: Renal (primarily as metabolites, ~1% unchanged). Fecal excretion is negligible for both.
Renal excretion of conjugated salicylate metabolites (75% as salicyluric acid, 10% as salicyl phenolic glucuronide, 5% as salicyl acyl glucuronide, 5% as gentisic acid); 10% free salicylate; approximately 10% eliminated in feces via bile.
Ibuprofen: >99% bound to albumin; Diphenhydramine: 78-85% bound to albumin.
80-90% bound to albumin; binding is concentration-dependent and saturable.
Ibuprofen: 0.1-0.2 L/kg; small Vd consistent with high protein binding. Diphenhydramine: 4.5-8.5 L/kg; large Vd indicating extensive tissue distribution.
0.15-0.2 L/kg for salicylate; distributes into synovial fluid, CNS, and placental tissues; Vd increases in acidosis.
Ibuprofen: 80-100% (oral); Diphenhydramine: 50-70% (oral) due to first-pass metabolism.
Oral: Approximately 100% for immediate-release, but extended-release may have slightly reduced absorption (relative bioavailability 85-90% compared to immediate-release).
Avoid use in GFR <30 m L/min. For GFR 30-59 m L/min, limit to single dose and avoid chronic use. No adjustment needed for GFR ≥60 m L/min.
Avoid in severe renal impairment (Cr Cl <30 m L/min). Use with caution and monitor for bleeding in moderate impairment. Reduce dose or extend interval.
Contraindicated in Child-Pugh Class C. In Child-Pugh Class B, reduce dose by 50% (max 1 caplet) and monitor for toxicity. No adjustment for Child-Pugh Class A.
Avoid in severe hepatic impairment. Use with caution in moderate impairment; monitor liver function.
Not recommended for children under 12 years. For age ≥12 years, same adult dose: 2 caplets at bedtime.
Not recommended in children <12 years for viral infections due to Reye's syndrome risk (contraindicated).
Start with lowest effective dose (1 caplet) at bedtime to minimize anticholinergic and GI adverse effects. Avoid in elderly with cognitive impairment or high fall risk.
Increased risk of GI bleeding and renal impairment; use lowest effective dose, monitor renal function and signs of bleeding.
NSAIDs cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. This risk may occur early in treatment and may increase with duration of use. NSAIDs are contraindicated in the setting of coronary artery bypass graft (CABG) surgery.
None
Cardiovascular thrombotic events,Gastrointestinal bleeding, ulceration, and perforation,Renal toxicity,Sedation and impaired cognitive function,Anticholinergic effects,Avoid use with other NSAIDs or antihistamines,Use caution in elderly, renal impairment, hepatic impairment, and pregnancy
Increased risk of gastrointestinal bleeding and ulceration; Reye syndrome in children with viral illness; Hemorrhagic stroke risk with high doses; Impaired renal function in predisposed patients; Bronchospasm in aspirin-sensitive asthma; Anaphylactic reactions; Use caution in patients with hepatic impairment or G6PD deficiency.
Hypersensitivity to ibuprofen, diphenhydramine, or any component of the formulation,History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs,Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery,Neonates and premature infants (due to diphenhydramine),Concurrent use with other diphenhydramine products or sedatives
Known hypersensitivity to NSAIDs or aspirin; Active peptic ulcer disease or GI bleeding; Severe renal impairment (e GFR <30 m L/min); Hemorrhagic diathesis; Children with viral infection (Reye syndrome); Third trimester of pregnancy; Severe hepatic impairment.
Take with food or milk to reduce GI upset. Avoid alcohol and grapefruit juice. Caffeine may enhance CNS stimulation and should be limited.
Avoid alcohol; may increase risk of gastrointestinal bleeding. No specific food restrictions, but taking with food can reduce gastric irritation. Avoid high-dose vitamin C supplements as they may increase salicylate levels.
Pregnancy Category C/D (after 30 weeks). First trimester: Potential risk of miscarriage and cardiac defects (limited data with NSAIDs). Second trimester: Avoid unless clearly needed; possible oligohydramnios, premature closure of ductus arteriosus, and fetal renal impairment. Third trimester: Contraindicated after 30 weeks due to risk of premature ductus arteriosus closure and persistent pulmonary hypertension.
First trimester: No well-controlled studies. Avoid use unless clearly needed. Second and third trimesters: Aspirin should be avoided due to risk of premature closure of ductus arteriosus, oligohydramnios, and increased risk of maternal and fetal bleeding. High doses may cause constriction of ductus arteriosus in utero and persistent pulmonary hypertension in newborn.
Diphenhydramine and ibuprofen are excreted into breast milk. M/P ratio not established. Both drugs are considered compatible with breastfeeding in low doses, but theoretical risk of infant sedation (diphenhydramine) and gastrointestinal effects (ibuprofen). Max daily dose for mother should not exceed recommended limits. Monitor infant for drowsiness and poor feeding.
Small amounts of aspirin are excreted in breast milk. M/P ratio not established. Use with caution in breastfeeding women; avoid high doses due to risk of Reye's syndrome in infants and potential for adverse effects on platelet function.
No specific dose adjustment recommended for ibuprofen or diphenhydramine in pregnancy. However, due to altered pharmacokinetics (increased volume of distribution, renal clearance), standard doses may be less effective. Avoid use if possible, especially after 30 weeks. Use lowest effective dose for shortest duration.
Pregnancy increases clearance of aspirin; however, dose adjustments are not routinely recommended due to narrow therapeutic index. Use lowest effective dose for shortest duration. Avoid in third trimester.
Advil PM combines ibuprofen (NSAID) and diphenhydramine (antihistamine). Avoid concomitant use with other NSAIDs or CNS depressants (including alcohol). Use lowest effective dose for shortest duration. Contraindicated in severe hepatic/renal impairment, active GI bleeding, or during third trimester of pregnancy. May cause morning drowsiness due to antihistamine.
8-Hour Bayer is enteric-coated aspirin designed for extended release, reducing gastrointestinal irritation. Onset of action is delayed; not suitable for acute pain or rapid antiplatelet effect. Use with caution in patients with history of peptic ulcer disease or on anticoagulants. Monitor renal function in elderly or dehydrated patients. Avoid in children with viral illness due to Reye's syndrome risk.
Take only one tablet before bedtime; do not exceed recommended dose.,Avoid alcohol and other sedatives while using this medication.,Do not use for more than 10 days for pain or 3 days for fever unless directed by a doctor.,May cause drowsiness; avoid driving or operating machinery until you know how the drug affects you.,Not for use in children under 12 years of age or during pregnancy/breastfeeding without consulting a healthcare provider.,Report signs of stomach bleeding (e.g., black/tarry stools, vomiting blood) or allergic reactions (e.g., facial swelling, difficulty breathing).
Take with a full glass of water; do not crush or chew the tablet.,Do not use within 7 days before surgery due to bleeding risk.,If used for pain, consult a doctor if symptoms persist for more than 10 days.,Avoid alcohol while taking this medication to reduce stomach bleeding risk.,Seek medical attention for signs of bleeding (black stools, blood in vomit).
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 ADVIL PM vs 8-HOUR BAYER, answered by our medical review team.
ADVIL PM is a NSAID/Sedative Combination that works by Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis. Diphenhydramine is a first-generation antihistamine that antagonizes histamine H1 receptors, causing sedation.. 8-HOUR BAYER is a NSAID that works by Irreversibly acetylates cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), inhibiting prostaglandin and thromboxane A2 synthesis, leading to analgesic, antipyretic, anti-inflammatory, and antiplatelet effects.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ADVIL PM and 8-HOUR BAYER 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 ADVIL PM is: Two caplets (ibuprofen 200 mg, diphenhydramine citrate 38 mg) orally at bedtime as needed for insomnia. Maximum: 2 caplets in 24 hours.. The standard adult dose of 8-HOUR BAYER is: 325-650 mg every 8 hours for pain/fever; 81-325 mg daily for cardiovascular prophylaxis.. 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 ADVIL PM and 8-HOUR BAYER 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. ADVIL PM is classified as Category C. Pregnancy Category C/D (after 30 weeks). First trimester: Potential risk of miscarriage and cardiac defects (limited data with NSAIDs). Second trimester: Avoid unless clearly neede. 8-HOUR BAYER is classified as Category C. First trimester: No well-controlled studies. Avoid use unless clearly needed. Second and third trimesters: Aspirin should be avoided due to risk of premature closure of ductus arte. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.