Dosage: How to Read, Calculate, and Use Medication Doses Safely

Confused by milligrams, micrograms, or mL on a bottle? You’re not alone. This page gives clear, practical rules you can use the next time you need to figure out a dose, measure liquid medicine, or follow a titration plan. Read this before changing any medication — then check with your prescriber or pharmacist.

Quick dose calculations and examples

Basic formula: dose (mg) = dose (mg/kg) × weight (kg). If a child needs 50 mg/kg/day and weighs 15 kg, the total daily dose is 750 mg. If the prescription says to give that in two doses, give 375 mg every 12 hours.

Common, easy examples you’ll see:

• Paracetamol (acetaminophen) for adults: usually 500–1000 mg every 4–6 hours as needed; many sources cap at 4,000 mg per day (always follow your provider’s limit).
• Pediatric antibiotic example: amoxicillin often dosed 25–50 mg/kg/day divided into two or three doses — follow the exact regimen on the script.
• Metformin (type 2 diabetes): commonly started at 500 mg once or twice daily, then slowly increased to the target dose. Don’t jump doses without advice.

Practical dosing tips: measuring, adjusting, and safety

Units matter. mg = milligram, mcg = microgram (1 mcg = 0.001 mg), IU = international units, and mL measures liquid volume. Confusing units cause mistakes. If anything looks off, call the pharmacy.

Use a proper dosing syringe for liquids — kitchen spoons aren’t accurate. For pills, only split tablets that are scored and labeled as safe to split. Never cut or crush extended-release tablets; the dose-release design can be ruined.

Adjustments: kidneys and liver change how drugs behave. If you or a family member has kidney or liver problems, doses often need lowering. Age matters too: older adults usually start at lower doses; children use weight-based doses. Always check the medication leaflet or ask a pharmacist for specific adjustments.

Missed dose? If it’s only a short time before the next dose, skip the missed one. Don’t double up to catch up. For critical medicines (like blood thinners or seizure drugs), follow the exact advice from your prescriber or the leaflet.

Drug interactions can change doses. For example, some drugs increase bleeding risk or sedative effects when combined. Before adding an over-the-counter pain reliever, herb, or supplement, ask whether your current meds need a dose change.

Titration is common for antidepressants, blood pressure meds, and some diabetes drugs. The prescriber will tell you how fast to increase the dose. If side effects show up, pause and contact your provider — a slower climb or lower target dose might be safer.

Want drug-specific dosing? Browse our dosage-tagged articles for step-by-step guides and real examples. Use this page as a practical checklist, then confirm with your healthcare team before making changes.