Dosage: How to Read, Measure, and Follow Medication Doses

Getting a medicine's dose right matters. A wrong dose can make a drug ineffective or cause harm. This page collects practical tips to help you understand dosage labels, measure medicines, and follow instructions from your healthcare provider. Read these ideas before you take pills or pour liquids.

Labels and prescriptions use different units — milligrams (mg), micrograms (mcg), milliliters (mL), and units. The prescription usually shows dose and frequency, like “10 mg once daily” or “5 mL every 8 hours.” If the label seems unclear, call your pharmacy. Never guess when the numbers don’t match what your doctor wrote.

Weight and age matter. Some drugs, especially for children, use mg per kilogram (mg/kg). That means the same medicine needs different amounts depending on body weight. Older adults may need lower doses because their bodies process drugs more slowly. If you see dosing based on weight, ask the prescriber for the correct calculation for your child or yourself.

Measuring liquids and breaking tablets

Use the right tools. Measuring spoons from the kitchen are not accurate. Use a marked oral syringe or dosing cup that comes with the medicine. When breaking tablets, use a pill cutter for even halves — do not snap by hand. Some tablets are scored to split; others are not safe to split because they release the drug slowly or unevenly.

Missed doses, changes, and safety

If you miss a dose, check the label or ask your pharmacist. For many meds, take the missed dose as soon as you remember unless it’s near the next scheduled dose. Don’t double up to catch up unless your prescriber tells you to. For short-term pain meds like ketorolac, stick to the recommended maximum daily dose and duration to avoid side effects. For statins like simvastatin, keep a consistent daily timing because steady levels help control cholesterol.

Watch for interactions. Some drugs interact with food, supplements, or other meds. For example, grapefruit juice can change how certain drugs work. Antifungals like ketoconazole and nerve pain meds like pregabalin or gabapentin may need careful dose adjustments if taken with other prescriptions. Always list all medications and supplements when you talk to your clinician.

Keep a dosing plan. Use a pillbox, set phone reminders, or mark a paper chart. Bring your medicine list to every medical visit so doses are reviewed. When a provider suggests a dose change, ask why and what side effects to watch for.

When in doubt, ask. Your pharmacist and prescriber can explain dosing clearly. If side effects start or you’re unsure about measurement, reach out right away. Safe dosing keeps medicine working the way it should and lowers risks.

Special situations need special care. Pregnancy, breastfeeding, kidney or liver disease often require dose changes. Tell your clinician if you have any of these. Also watch storage — some medicines need refrigeration or must be kept away from light. Correct storage helps maintain the dose you expect to get. If unsure, check the leaflet or ask the pharmacist. Keep records of dose changes.