Dosage: Practical rules for safer medication use

Getting a dose wrong is one of the easiest mistakes to make—and one of the riskiest. A single clear rule helps: dose = drug + amount + timing. If any of those pieces is off, the medicine can be less effective or harmful. Below are practical tips you can use right away.

Measure and double-check

Always use the measuring device that comes with the medicine. Kitchen teaspoons are not accurate. For liquids, use the syringe or marked cup. If a label says 5 mg per mL and you need 10 mg, that’s 2 mL. If the math feels fuzzy, ask the pharmacist to show you.

If your prescription lists weight-based dosing—for example, 5 mg/kg—do the math with the current weight. Example: a child who weighs 20 kg gets 5 × 20 = 100 mg. If tablets are 50 mg, that’s two tablets. Write the calculation down so you don’t forget.

Know milligrams (mg) vs milliliters (mL). Mg is drug amount; mL is liquid volume. Confusing them can change the dose entirely.

Timing, missed doses, and special formulations

Follow the timing on the label: once daily, twice daily, or as needed. For extended-release (XR/ER) tablets, don’t crush or split unless the label or your provider says it’s safe. Crushing an XR pill can release all the drug at once.

Missed dose? If it’s close to the next scheduled dose, skip the missed one—don’t double up. For some medicines, like antibiotics or blood thinners, timing matters more; call your provider if you’re unsure.

Be careful with tablet splitting. Use a pill cutter for even halves. If the tablet is film-coated or scored oddly, check with your pharmacist before splitting.

Watch for interactions. Some drugs must be taken with food, others on an empty stomach. Certain meds react poorly with alcohol or common supplements. Ask the pharmacist to list the top two things to avoid for any new prescription.

Adjustments for age, kidney, and liver: Older adults and people with kidney or liver issues often need lower doses or longer intervals. If you have reduced kidney function, drugs that clear through the kidneys can build up and cause toxicity. The same applies to liver-metabolized drugs—damage there can slow breakdown. Your doctor should adjust dosing, but you should remind them about kidney/liver problems and any other meds you take.

When to call for help: signs of an overdose include extreme sleepiness, trouble breathing, severe dizziness, or seizures. If you suspect overdose, call emergency services or poison control immediately.

Final practical tip: keep a simple dosing log for anyone on multiple medicines. List drug, dose, time, and who gave it. This prevents missed or doubled doses and makes conversations with providers simpler and safer.

If anything about a dose confuses you, ask. Pharmacists love dose questions and can check math, show measuring tools, and point out interactions. A quick question now can prevent a big problem later.