Calculate safe paracetamol (acetaminophen) doses for adults and children by weight. Includes pediatric liquid dosing, liver risk assessment, and combination product warnings.
The Paracetamol Dosage Calculator determines safe, weight-based dosing for paracetamol (known as acetaminophen in the US, and sold under brand names including Tylenol, Panadol, and Calpol). It is the most commonly used analgesic and antipyretic worldwide, available in dozens of formulations from infant drops to adult extra-strength tablets, rectal suppositories, and intravenous solutions.
Safe dosing of paracetamol is critically important because acetaminophen overdose is the leading cause of acute liver failure in developed countries. The therapeutic window is narrower than most people realize: the standard maximum of 4,000 mg/day for healthy adults drops to just 2,000 mg/day for those with liver disease or chronic alcohol use. Adding to the danger, acetaminophen is hidden in over 600 combination products — cold medicines, sleep aids, prescription opioid combinations — making accidental overdose through "double-dosing" a serious risk.
This calculator provides weight-based dosing for both adults and children, converts doses into practical formulation units (tablets or mL of liquid), tracks total daily intake against safe maximums, adjusts limits for liver disease and alcohol use, and includes a reference table of common combination products containing hidden acetaminophen. Pediatric dosing uses the standard 15 mg/kg per dose guideline with a maximum of 75 mg/kg/day.
Acetaminophen overdose sends over 50,000 people to emergency rooms annually in the US. The biggest risk factor is not intentional overdose but accidental double-dosing from multiple products containing hidden acetaminophen. This calculator helps track total daily intake and alerts users to combination product risks. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain.
Pediatric: 10–15 mg/kg per dose every 4–6 hours (max 75 mg/kg/day, not exceeding 4000 mg/day) Adult: 500–1000 mg per dose every 4–6 hours (max 4000 mg/day) Liver disease/alcohol: max 2000 mg/day Hepatotoxicity threshold: ~150 mg/kg in 24 hours Potentially lethal: ~350 mg/kg in 24 hours
Result: 375 mg per dose (15 mg/kg); 1500 mg/day (60 mg/kg/day); within safe range of 1875 mg/day max
A 25 kg child receiving 375 mg (15 mg/kg) four times daily totals 1500 mg/day (60 mg/kg/day), which is within the 75 mg/kg/day maximum of 1875 mg. Each dose equals 11.7 mL of 160 mg/5 mL suspension.
Despite being used for over a century, the exact mechanism of paracetamol remains debated. It is believed to work primarily through central inhibition of cyclooxygenase (COX) enzymes, particularly a COX-3 variant, and may also modulate the endocannabinoid system and serotonergic pathways. Unlike NSAIDs, paracetamol has minimal anti-inflammatory activity, making it better described as an analgesic and antipyretic rather than a true anti-inflammatory drug. Its advantage over NSAIDs is the absence of gastrointestinal, renal, and platelet toxicity at therapeutic doses.
When paracetamol is metabolized normally, about 90% undergoes glucuronidation and sulfation to harmless metabolites. However, 5–10% is oxidized by CYP2E1 to the toxic metabolite NAPQI (N-acetyl-p-benzoquinone imine), which is normally detoxified by glutathione conjugation. In overdose, glutathione stores are depleted, and NAPQI accumulates, causing hepatocellular necrosis. N-acetylcysteine (NAC) is the antidote — it replenishes glutathione and is nearly 100% effective if given within 8 hours of overdose. Effectiveness declines but remains significant up to 72 hours post-ingestion.
Paracetamol is sold under over 100 brand names worldwide: Tylenol (US/Canada), Panadol (UK/Australia/Asia), Calpol (UK pediatric), Doliprane (France), Ben-u-ron (Germany/Portugal), Efferalgan (Europe), and Crocin (India). Available formulations include standard tablets, effervescent tablets, liquid suspensions, infant drops with measured droppers, rectal suppositories, and intravenous solution (Ofirmev/Perfalgan) for hospital use. Despite identical active ingredients, formulation concentrations vary significantly between products and countries.
Healthy adults can take up to 4,000 mg (4 g) per day, with no more than 1,000 mg per dose and at least 4 hours between doses. If you have liver disease or drink 3+ alcoholic drinks daily, the maximum drops to 2,000 mg per day.
The standard pediatric dose is 10–15 mg/kg per dose, given every 4–6 hours, with a maximum of 75 mg/kg per day. Use the child's actual weight, not age-based guidelines, for the most accurate dosing.
Yes. Paracetamol and acetaminophen are the same drug (chemical name: N-acetyl-para-aminophenol). "Paracetamol" is used in most of the world, while "acetaminophen" is the term used primarily in the US, Canada, and Japan.
Early symptoms (first 24 hours) may be mild — nausea, vomiting, abdominal pain, or no symptoms at all. Liver damage develops silently over 24–72 hours, with jaundice, coagulopathy, and potentially fatal hepatic failure. Early treatment with N-acetylcysteine (NAC) is critical.
Yes, paracetamol and ibuprofen work through different mechanisms and can be safely alternated or taken together for enhanced pain relief. This combination is especially useful for dental pain, fever in children, and post-surgical pain.
Check the "Drug Facts" label of every OTC medication for "acetaminophen" in the active ingredients. Many cold medicines, sleep aids, and prescription painkillers contain 325–500 mg per dose. Add all sources together to stay under 4,000 mg/ day total.