Paracetamol (Acetaminophen) 1000mg 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. The 1000mg strength is a standard adult single dose, often used for more significant pain or as a single daily dose in certain extended-release formulations.
Adult: 1000mg every 4-6 hours as needed for pain/fever. Maximum daily dose: 4000mg (4 grams). Do not exceed 8 tablets/capsules of 500mg or 4 tablets of 1000mg in 24 hours.
Note: Take with or without food. Swallow the tablet whole with a full glass of water. Do not crush or chew unless specified (e.g., dispersible tablets). For faster absorption, take on an empty stomach. Do not take for more than 3 days for fever or 5 days for pain without consulting a doctor.
The exact mechanism is not fully elucidated but is distinct from NSAIDs. It is a potent inhibitor of cyclooxygenase (COX) enzymes, particularly in the central nervous system (CNS). It is believed to act primarily on the COX-2 variant and a putative central COX-3 enzyme. It reduces the production of prostaglandins in the brain (hypothalamus), which mediates its antipyretic effect and central analgesic action. It has minimal effect on peripheral COX-1, accounting for its lack of significant anti-inflammatory activity and GI side effects.
Pregnancy: Category A (Australian categorization). Widely used and considered safe for short-term use in all trimesters at recommended doses. Crosses the placenta. Avoid long-term/high-dose use.
Driving: No known effects on driving ability.
| Warfarin and other Coumarin Anticoagulants | Increased INR 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, elevating hepatotoxicity risk. | Major |
| Probenecid | Decreases paracetamol conjugation, may increase its half-life and effect. | 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, depletes glutathione, significantly increasing risk of hepatotoxicity even at therapeutic doses. | Major |
| Other Hepatotoxic Drugs (e.g., Methotrexate, Azathioprine, Ketoconazole) | Additive risk of liver damage. | Major |
Same composition (Paracetamol (1000mg)), different brands: