Prescribing Guides
Paracetamol (Acetaminophen) Prescribing Guide for Indian Clinical Practice
Essential paracetamol prescribing guide for Indian clinicians covering hepatotoxicity thresholds, dosing, overdose management and NEET PG points.
MedNext Editorial Team | 2026-08-01 | 8 min read
Paracetamol (Acetaminophen) Prescribing Guide for Indian Clinical Practice
Essential paracetamol prescribing guide for Indian clinicians covering hepatotoxicity thresholds, dosing, overdose management and NEET PG points.
Paracetamol (acetaminophen) is the most widely used analgesic and antipyretic in India. Available over the counter for mild to moderate pain and fever, it carries a narrow therapeutic-to-toxic ratio that every clinician must respect.
Clinical Pharmacology Overview
Paracetamol is a para-aminophenol derivative that acts primarily through central inhibition of cyclooxygenase, possibly via a COX-3 isoform and modulation of the endocannabinoid system. It has analgesic and antipyretic properties but negligible peripheral anti-inflammatory activity, which is why it is not classified as an NSAID.
Pharmacokinetics: Rapidly and almost completely absorbed orally. Bioavailability is 70-90% (first-pass metabolism). Protein binding is 10-25%. Extensively metabolised in the liver -- 90% by glucuronidation and sulphation (non-toxic), 5-10% by CYP2E1 to the toxic metabolite NAPQI, which is normally detoxified by glutathione. Half-life is 2-3 hours.
Indian Brand Names
- Crocin (GSK Consumer Healthcare)
- Dolo (Micro Labs)
- Calpol (GSK)
- Pacimol (Ipca Laboratories)
- Metacin (ICPA Health Products)
Approved Indications in Indian Clinical Practice
- Mild to moderate pain (headache, musculoskeletal pain, dental pain, post-operative pain)
- Fever reduction
- Osteoarthritis (as first-line analgesic)
- Adjunct in multimodal analgesia (post-surgical pain management)
- Antipyretic in dengue fever (NSAIDs are contraindicated in dengue)
Dosing in Adults
Oral: 500-1000 mg every 4-6 hours as needed. Maximum: 4 g per day.
IV (Perfalgan): 1 g every 6 hours. Maximum: 4 g per day. For patients under 50 kg: 15 mg/kg per dose.
Reduced maximum (2 g/day) in: hepatic impairment, chronic alcohol use, malnutrition, body weight under 50 kg.
Rectal: 0.5-1 g every 4-6 hours (absorption is variable and slower).
Important Drug Interactions
- Warfarin: regular paracetamol use (more than 2 g/day for over a week) can raise INR
- Carbamazepine, phenytoin, rifampicin: CYP enzyme inducers increase NAPQI formation, raising hepatotoxicity risk
- Alcohol: chronic use depletes glutathione and induces CYP2E1, lowering the toxic threshold
- Metoclopramide, domperidone: enhance paracetamol absorption by accelerating gastric emptying
- Cholestyramine: reduces paracetamol absorption if given within 1 hour
Side Effects and Monitoring
At therapeutic doses, paracetamol is remarkably well tolerated with minimal GI, renal, or platelet effects.
Serious: hepatotoxicity in overdose (the leading cause of acute liver failure in many countries). Toxic dose threshold: more than 150 mg/kg or more than 7.5 g in adults.
Overdose management: gastric decontamination if within 1 hour, serum paracetamol level at 4 hours, Rumack-Matthew nomogram, N-acetylcysteine (NAC) as antidote.
Rare at therapeutic doses: thrombocytopenia, skin reactions.
Special Populations
Pregnancy: Category B. The safest analgesic-antipyretic in pregnancy. First-line for pain and fever in all trimesters.
Renal impairment: Extend dosing interval to every 6-8 hours in severe renal impairment (GFR < 10 mL/min).
Hepatic impairment: Use with extreme caution. Reduce maximum daily dose to 2 g. Avoid in acute liver disease or decompensated cirrhosis.
Elderly: Reduce to 2-3 g/day maximum. Increased hepatotoxicity risk due to reduced glutathione stores and polypharmacy.
NEET PG High-Yield Points
- Toxic metabolite: NAPQI (N-acetyl-p-benzoquinone imine), formed by CYP2E1
- Antidote: N-acetylcysteine (NAC) -- replenishes glutathione
- Rumack-Matthew nomogram: plot serum level at 4 hours post-ingestion
- Not an NSAID -- no anti-inflammatory effect, no GI bleeding, no platelet dysfunction
- Safest analgesic in pregnancy
- Preferred antipyretic in dengue (NSAIDs increase bleeding risk)
- Hepatotoxicity potentiated by enzyme inducers and chronic alcohol
- CYP2E1 is the key enzyme in toxicity pathway
Indian Regulatory Status
Paracetamol is an over-the-counter (OTC) drug in India when sold as a single-ingredient formulation in packs containing limited quantities. Fixed-dose combinations containing paracetamol with other drugs (e.g., paracetamol + tramadol, paracetamol + ibuprofen) are Schedule H drugs requiring a prescription. The CDSCO has mandated prominent hepatotoxicity warnings on all paracetamol packaging. It is included in the NLEM and is price-controlled under DPCO.
Frequently Asked Questions
What is the maximum safe dose of paracetamol per day?
The maximum recommended dose for adults is 4 g per day (1 g every 6 hours). In patients with hepatic impairment, chronic alcohol use, or low body weight, the maximum should be reduced to 2 g per day. Indian packaging now carries hepatotoxicity warnings prominently.
What is the antidote for paracetamol overdose?
N-acetylcysteine (NAC) is the specific antidote. It replenishes hepatic glutathione stores and should be started within 8 hours of ingestion for maximum efficacy. The Rumack-Matthew nomogram guides treatment decisions based on serum paracetamol level at 4 hours post-ingestion.
Is paracetamol safe in pregnancy?
Paracetamol is considered the safest analgesic-antipyretic in pregnancy (Category B). It is the first-line choice for pain and fever in all trimesters of pregnancy in Indian obstetric practice.
Why is paracetamol not classified as an NSAID?
Paracetamol has minimal anti-inflammatory activity and does not significantly inhibit peripheral COX. It acts primarily centrally, possibly via COX-3 inhibition and the endocannabinoid system. It does not cause GI bleeding or platelet dysfunction, which distinguishes it from NSAIDs.
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