Paracetamol (Acetaminophen) is a widely used, centrally-acting, non-opioid analgesic and antipyretic agent. It is a first-line treatment for mild to moderate pain and fever. Unlike NSAIDs, it has minimal anti-inflammatory activity and a favorable gastrointestinal safety profile. It is one of the most commonly used over-the-counter (OTC) medications in India and globally.
Adult: 325-650 mg every 4-6 hours OR 500-1000 mg every 6-8 hours. Maximum daily dose: 4 grams (4000 mg).
Note: Oral tablet/capsule to be taken with or without food, with a full glass of water. Do not crush or chew unless specified (e.g., dispersible tablets). Should not be taken for more than 3 days for fever or 5 days for pain without medical advice.
The exact mechanism is not fully elucidated but is distinct from NSAIDs. It is a potent inhibitor of the cyclooxygenase (COX) pathways, particularly in the central nervous system. It is believed to act on the COX-3 isoform (a variant of COX-1) and other central pathways, including the serotonergic and cannabinoid systems, to produce analgesia and antipyresis. It has very weak peripheral anti-inflammatory effects.
Pregnancy: Category A (Australian categorization). Widely used and considered safe in all trimesters for short-term treatment of pain and fever at recommended doses. Crosses the placenta. Should be used at the lowest effective dose for the shortest duration.
Driving: No known effects on driving ability.
| Warfarin | Chronic high-dose paracetamol (>2g/day for several days) may potentiate anticoagulant effect by reducing synthesis of vitamin K-dependent clotting factors. Increases INR risk. | Major |
| Isoniazid | Increases formation of toxic metabolite NAPQI by inducing CYP2E1, significantly increasing risk of hepatotoxicity, even at therapeutic doses. | Major |
| Carbamazepine, Phenytoin, Phenobarbital | Enzyme inducers increase formation of NAPQI, increasing hepatotoxicity risk. | Moderate |
| Probenecid | Inhibits glucuronidation, may slightly increase and prolong paracetamol effect. | Minor |
| Metoclopramide, Domperidone | May increase absorption rate of paracetamol. | Minor |
| Cholestyramine | Reduces absorption of paracetamol if taken within 1 hour. | Minor |
| Alcohol (Chronic abuse) | Induces CYP2E1 and depletes glutathione, dramatically increasing risk of hepatotoxicity. Contraindicated. | Major |
| Other Hepatotoxic Drugs (e.g., Rifampicin, Sodium Valproate) | Additive risk of liver damage. | Major |