Generic
Acetaminophen
1 brands available in the market
At a glance
Acetaminophen (paracetamol) is an analgesic and antipyretic used for mild to moderate pain and fever. It inhibits prostaglandin synthesis in the central nervous system.
Description
Acetaminophen, also known as paracetamol, is an analgesic and antipyretic. Its exact mechanism is not fully understood, but it inhibits prostaglandin synthesis by selectively acting on cyclooxygenase enzymes in the central nervous system. It has weak anti-inflammatory action. It can be given orally, rectally, and intravenously. Short-term use is safe and effective, but overdose can cause severe hepatotoxicity.
Indications
Fever (antipyretic) and mild to moderate pain (analgesic) such as headache, toothache, muscle pain, menstrual pain, sore throat, and post-immunization fever.
Therapeutic class
Analgesic & Antipyretic
Pharmacological class
p-Aminophenol Derivative
Pharmacology
Acetaminophen is an analgesic and antipyretic. Its exact mechanism is not fully understood, but it inhibits prostaglandin synthesis in the central nervous system and has selective effects on cyclooxygenase (COX) enzymes. It has weak anti-inflammatory action. Oral bioavailability is approximately 80%. Plasma half-life is approximately 2-3 hours.
Mechanism of action
Acetaminophen reduces pain and fever by inhibiting prostaglandin synthesis in the central nervous system. It has selective effects on cyclooxygenase enzymes and weak anti-inflammatory properties.
Dosage
Adults: 650-1000 mg every 4-6 hours; maximum daily dose 4000 mg.
Children (weight-based):
- 2-4 years: 160 mg every 4-6 hours
- 4-6 years: 240 mg every 4-6 hours
- 6-9 years: 320 mg every 4-6 hours
- 9-11 years: 320-400 mg every 4-6 hours
- 11-12 years: 320-480 mg every 4-6 hours
- Children: every 4 hours, no more than 5 doses in 24 hours
Under 2 years: As directed by physician.
Administration
Can be taken with or without food. Swallow tablets whole; do not crush. Use a dosing syringe for liquid formulations.
Maximum daily dose: Adults: 4000 mg.
Missed dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not double the dose.
Side effects
Common side effects: Rare; generally well tolerated.
Serious side effects:
- Hepatotoxicity (liver necrosis) in overdose
- Severe skin reactions (rare)
- High anion gap metabolic acidosis (in at-risk patients)
Precautions & warnings
Considered safe during pregnancy and lactation. Caution in liver or severe kidney disease. Caution in patients with history of alcohol consumption. Patients with phenylketonuria (PKU) should avoid brands containing aspartame.
Contraindications
Hypersensitivity to acetaminophen or any component. Severe liver disease.
Drug interactions
Carbamazepine, phenytoin, phenobarbital, rifampicin: Enzyme-inducing drugs increase acetaminophen clearance and toxicity risk.
Warfarin: Acetaminophen may increase anticoagulant effect.
Food interactions
Caution advised with alcohol consumption; alcohol increases the risk of liver damage.
Use in pregnancy
Pregnancy Category: B. Can be used safely during pregnancy. Fever and pain treatment is important; avoid chronic or high-dose use.
Pregnancy Category: B — always consult a doctor before taking during pregnancy.
Use in lactation
Can be used safely during breastfeeding. Minimal excretion in breast milk; not harmful to the infant.
Pediatric use
Under 2 years: Use under medical supervision.
2-12 years: Weight-based dosing applies (see above).
≥12 years: Adult dose applies.
Geriatric use
No dose adjustment required for elderly patients; however, caution is advised due to reduced liver and kidney function.
Renal / hepatic impairment
Renal impairment: Severe renal impairment (CrCl <30 mL/min): increase dosing interval to 6 hours.
Hepatic impairment: Reduce dose in liver disease.
Overdose effects
Overdose symptoms: Nausea, vomiting, anorexia, sweating, lethargy.
Toxic dose: Adults: ≥10 g/24 hours; Children: ≥150 mg/kg.
Treatment: N-acetylcysteine (NAC) as soon as possible (most effective within 8 hours). Activated charcoal, symptomatic supportive measures.
Storage conditions
Store in a cool and dry place, protected from light and moisture. Below 30°C. Keep out of reach of children.
Chemical structure
C₈H₉NO₂