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.
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Medication Dosing Guide
What's the key thing to understand about 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 per dose, every 4-6 hours) should always be dosed by weight rather than age alone, since children of the same age can vary significantly in weight.
What should I know about 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 pregnancy — ibuprofen and other NSAIDs should be avoided from this point onwards due to risks to the baby, with paracetamol being the safer choice throughout pregnancy generally.
What should I know about 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): used for pain relief in adults, but never given to children or teenagers under 16 due to the risk of Reye's syndrome, a rare but serious condition linked to aspirin use in this age group.
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 medication packaging are a starting reference, not a substitute for checking with a pharmacist or GP if you're ever uncertain about dosing, especially for children or when combining medications.