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. In the Indian context, it is available as an oral solution/suspension (100mg/ml), making it particularly suitable for pediatric and geriatric populations, as well as patients with swallowing difficulties. It is considered one of the safest analgesics when used at recommended doses but carries a significant risk of dose-dependent hepatotoxicity in overdose.
Adult: 325-650 mg every 4-6 hours OR 500-1000 mg every 6-8 hours. Maximum daily dose: 4000 mg (4 grams). For 100mg/ml oral liquid: 3.25-6.5 ml every 4-6 hours.
Note: Shake the oral suspension well before use. Use the measuring cup or syringe provided for accurate dosing. Can be taken with or without food. If GI upset occurs, take with food. Do not combine with other paracetamol-containing products.
The exact mechanism is not fully elucidated but is distinct from NSAIDs. It is a potent inhibitor of cyclooxygenase (COX) pathways, particularly in the central nervous system. It has minimal peripheral anti-inflammatory activity. It is believed to act primarily by inhibiting a variant of the COX enzyme, sometimes referred to as COX-3, in the brain and spinal cord. It also modulates the endogenous cannabinoid system and serotonergic pathways, contributing to its analgesic effect.
Pregnancy: Category A (Australian categorization). Widely used and considered safe for short-term use at recommended doses throughout pregnancy. Crosses the placenta. Avoid excessive or long-term use.
Driving: No known effects on driving ability.
| Warfarin | Increased anticoagulant effect and risk of bleeding, especially with chronic high-dose paracetamol (>2g/day for several days). | Major |
| Isoniazid | Increased risk of hepatotoxicity due to induction of CYP2E1, increasing NAPQI formation. | Major |
| Enzyme Inducers (Phenobarbital, Phenytoin, Carbamazepine, Rifampicin) | Increased metabolism to toxic NAPQI, increasing risk of hepatotoxicity at therapeutic doses. | Major |
| Probenecid | Decreases paracetamol clearance by inhibiting glucuronidation, leading to increased plasma levels. | Moderate |
| Metoclopramide, Domperidone | Increased absorption rate of paracetamol. | Minor |
| Cholestyramine | Decreased absorption of paracetamol if taken within 1 hour. | Moderate |
| Alcohol (Chronic, heavy use) | Induces CYP2E1, increasing risk of hepatotoxicity. Acute alcohol may initially be protective by competing for CYP2E1. | Major |
| Other NSAIDs (e.g., Ibuprofen) | Concomitant use may increase risk of renal impairment, especially in dehydrated patients. Not typically additive for analgesia. | Moderate |