Acetaminophen

Nursing pharmacology study reference (NCLEX-style monograph). Numeric values are standard teaching ranges for study and must be verified against current manufacturer labeling before clinical use. This is educational content, not prescribing guidance.

Acetaminophen (brand name Tylenol) — Analgesic, antipyretic; Para-aminophenol derivative.

Identification

• Therapeutic class: Analgesic, antipyretic.
• Pharmacologic class: Para-aminophenol derivative.

Pharmacology

• Mechanism of action: Acts centrally to reduce pain and fever; little anti-inflammatory effect and no antiplatelet or GI ulcer effect.
• Onset / peak / duration: PO onset 30 to 60 minutes; IV faster; duration 4 to 6 hours.
• Half-life / therapeutic level: Half-life about 2 hours; toxic level guides acetylcysteine dosing.

Clinical use

• Indications: Mild to moderate pain, fever.
• Usual dose, route, frequency: 325 to 1,000 mg PO every 4 to 6 hours; IV and rectal available.
• Maximum dose / adjustments: Max 4 g/day (often capped at 3 g/day, lower with liver disease or alcohol use); count all combination products.

Safety

• Contraindications: Severe hepatic impairment, hypersensitivity.
• Black box warning: None (the label warns of severe hepatotoxicity above recommended doses).
• Interactions: Warfarin (raises INR at high regular doses), alcohol (hepatotoxicity, food/drink), other acetaminophen-containing products.
• Pregnancy / lactation: Preferred analgesic and antipyretic in pregnancy.
• High-alert: No.

Adverse effects

• Common side effects: Generally well tolerated.
• Serious effects to report: Hepatotoxicity (right upper abdominal pain, jaundice), rare severe skin reactions.
• Antidote / reversal: Acetylcysteine for overdose.

Nursing process

• Assessment before administration: Pain or fever, total daily acetaminophen from all sources, liver function and alcohol use.
• Interventions during therapy: Add up every source to stay within the daily limit.
• Monitor: Pain and fever relief, LFTs with high or chronic use.
• Evaluation / expected outcome: Reduced pain or fever.

Patient teaching

• Patient teaching: Do not exceed the daily limit; check combination cold and pain products for hidden acetaminophen; limit alcohol.
• Notify provider if: Right upper abdominal pain, yellowing of skin, dark urine.
• Administration tips: Track total daily dose across all products.