Weight-Based Medication Dose Calculator
Calculate weight-based doses for common over-the-counter medications. For reference only — always follow the prescriber, pharmacist, or package instructions.
Medication Dosing Guide
Paracetamol — The Safest Starting Point
Paracetamol (acetaminophen) is the safest analgesic and antipyretic for most people including pregnant women, children, and the elderly. Adults: 500mg-1,000mg every 4-6 hours. Maximum 4,000mg (4g) in 24 hours. Overdose: paracetamol overdose is the leading cause of acute liver failure in the UK — often accidental (taking multiple products unknowingly containing paracetamol). Always check other medications (cold/flu remedies, codeine combinations) do not also contain paracetamol. Children (15mg/kg
Ibuprofen — Anti-Inflammatory
Ibuprofen is an NSAID — anti-inflammatory, analgesic, and antipyretic. Adults: 200-400mg every 4-8 hours with food. Maximum 1,200mg/day (OTC limit). Prescription: up to 2,400mg/day. Children (over 3 months, over 5kg): 5-10mg/kg per dose, every 6-8 hours. Always give with food. Contraindications — do not use without medical advice: asthma (NSAID sensitivity in approximately 10% of asthmatics). Stomach ulcers or GI problems. Kidney disease. Heart disease or stroke history. Third trimester of pregn
Never Use Aspirin in Children Under 16
Aspirin is absolutely contraindicated in children and teenagers under 16 due to the risk of Reye's syndrome — a rare but potentially fatal condition causing liver and brain damage. This applies even to low-dose aspirin (75mg). If a child has fever, use paracetamol or ibuprofen. Aspirin in adults: low-dose aspirin (75mg daily) is prescribed as an antiplatelet drug for cardiovascular disease prevention. Standard-dose aspirin (300mg) is used acutely for suspected heart attacks. OTC aspirin (300mg):
When to Seek Medical Advice
Seek medical advice before self-medicating if: fever in a child under 3 months. Fever lasting more than 3 days in children. Fever above 39.5°C unresponsive to medication. Any sign of serious illness (rash, difficulty breathing, confusion, severe headache). Pain not controlled by OTC doses. Regular need for pain relief (more than a few days per week). Any sign of overdose: nausea, vomiting, abdominal pain within 24 hours of high paracetamol dose — attend A&E immediately. The dose charts on medica
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