Paracetamol
Generic Name: Paracetamol (Acetaminophen)
Uses & Medical Indications
First-line therapy for the symptomatic relief of mild to moderate pain (tension headache, toothache, musculoskeletal pain, osteoarthritis, dysmenorrhea) and reduction of pyrexia (fever) in viral or bacterial infections.
Fever, Tension Headache, Osteoarthritis, Toothache, Dysmenorrhea, Post-vaccination pyrexia
Work Mechanism & Pharmacology
Patient Overview of Work Mechanism
Paracetamol acts in the brain and spinal cord to turn down pain signaling and recalibrate the body's internal thermostat in the hypothalamus, rapidly easing fever and mild-to-moderate aches without causing stomach ulcers.
Clinical Mechanism of Action (MoA)
Centrally active analgesic and antipyretic agent. Inhibits central nervous system cyclooxygenase (COX-1, COX-2, and splice variant COX-3), preventing prostaglandin E2 (PGE2) synthesis in the hypothalamus and spinal dorsal horn. Activates descending serotonergic pain inhibitory pathways and undergoes metabolic conversion via FAAH into AM404, an active metabolite that stimulates cannabinoid CB1 receptors and TRPV1 channels.
Dosage & Administration Guidelines
500 mg to 1000 mg orally every 4 to 6 hours as needed. Maximum 4000 mg (4 grams) in 24 hours. In underweight adults (<50 kg) or hepatic impairment, limit to 2000-3000 mg daily.
10 to 15 mg/kg per dose orally every 4 to 6 hours as needed. Maximum 5 doses (or 60-75 mg/kg) in 24 hours. Do not exceed adult maximum.
Same as adult; in frail elderly patients with malnutrition or hepatic impairment, 500 mg every 6 to 8 hours (max 2-3 g/day).
4000 mg (4 grams) per 24 hours for healthy adults.
CrCl 10-50 mL/min: administer every 6 hours. CrCl <10 mL/min: administer every 8 hours.
Contraindicated in severe acute hepatic failure or active decompensated liver disease. Reduce dose in chronic mild/moderate liver impairment.
Side Effects & Safety Warnings
Nausea, mild epigastric discomfort, pruritus, transient constipation.
Hepatotoxicity (centrilobular hepatic necrosis in overdose), acute liver failure, Stevens-Johnson Syndrome (rare), thrombocytopenia.
Severe active hepatic impairment, hypersensitivity to paracetamol.
Accidental overdose can occur when taking multiple over-the-counter cold/cough formulations containing paracetamol concurrently.
Interactions (Drugs, Food & Alcohol)
Warfarin (chronic daily use >2g/day may enhance anticoagulant effect and increase INR), Isoniazid, Carbamazepine, Phenytoin.
High-pectin or high-carbohydrate meals may slightly delay gastric absorption.
Chronic heavy alcohol consumption markedly increases hepatotoxicity risk due to CYP2E1 induction and glutathione depletion.
Identified Clinical Drug Interactions for Paracetamol:
Elevated risk of severe, irreversible hepatotoxicity even at standard or slightly supratherapeutic paracetamol doses.
INR Elevation with Regular High-Dose Acetaminophen
Pregnancy & Breastfeeding Safety
Widely considered the safest analgesic and antipyretic of choice in all trimesters of pregnancy at the lowest effective dose for the shortest duration.
Compatible with breastfeeding; excreted in breast milk in negligible amounts with no adverse effects observed in nursing infants.
Patient Counseling & Practical Advice
Always check labels of all cold, flu, and cough medications to avoid accidentally doubling your paracetamol dose.
Take when needed. Do not take extra medicine to make up for a forgotten dose.
In long-term or high-dose therapy: Liver function tests (ALT, AST, total bilirubin), serum creatinine.
Frequently Asked Questions
Related Medicines in Analgesic
When to Seek Urgent Medical Attention
Overdose symptoms: Nausea, vomiting, severe right upper quadrant abdominal tenderness, confusion, diaphoresis. Antidote is N-acetylcysteine (NAC).
Content for Paracetamol was synthesized from standardized public health monographs, official pharmacopoeias, and health authorities:
- World Health Organization (WHO) — WHO Model Formulary - Paracetamol Monograph
- British National Formulary (BNF) — BNF Paracetamol Clinical Prescribing Guide
The information provided on this website is for educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition.