Here's how to measure liquid medicine safely: use the oral syringe, dosing cup or dropper that came with it, never a kitchen spoon. Check that the units on the device match the units on the label, measure in good light at eye level, and ask your pharmacist whenever the label and the device don't match.
This is general information, not medical advice. Talk to your doctor or pharmacist about your own situation.
This is an example routine built from FDA, MedlinePlus and Institute for Safe Medication Practices (ISMP) tips. It doesn't replace the directions on your label.
Read the label every time. The FDA says to read and follow the label directions every time, paying special attention to directions and warnings.
Shake if needed. MedlinePlus says to shake a suspension well before using it.
Use the device that came with the medicine. ISMP says to use only the device that comes with the medicine, and never to use a device from one medicine for a different one.
Match the units. MedlinePlus advises checking that the units on the cup or syringe, such as teaspoon, tablespoon, mL or cc, match the units of the dose. The FDA's example: if the label says teaspoons and your cup only shows ounces, don't guess. Get the proper measuring device.
Turn on the light and get level. ISMP says not to measure in a dim room or when you're very tired or distracted. Put your glasses on. Read a cup or dosing spoon at eye level, ideally on a flat surface.
Don't pour extra back. If you overfill, ISMP says to discard the excess rather than pour it back, which would contaminate the rest of the bottle.
Close it up. Replace the cap right away and make sure a child-resistant cap locks.
Clean and store. Wash the device after each use, and dry it well before the next dose. ISMP suggests keeping the device with the bottle, for example with a rubber band, so the right tool is always on hand.
MedlinePlus says eating spoons aren't all the same size. A flatware teaspoon could hold as little as half a teaspoon (2.5 mL) or as much as 2 teaspoons (10 mL). Measuring spoons used for cooking are accurate, it notes, but they spill easily. The FDA's advice is not to substitute another item, such as a kitchen spoon, for the proper dosing device. ISMP adds that both the FDA and the American Academy of Pediatrics discourage using kitchen spoons.
The FDA suggests knowing these abbreviations: tsp (teaspoon), tbsp (tablespoon), mg (milligram), mL (milliliter) and oz (ounce). MedlinePlus lists these conversions:
1 mL = 1 cc
2.5 mL = 1/2 teaspoon
5 mL = 1 teaspoon
15 mL = 1 tablespoon
3 teaspoons = 1 tablespoon
Conversions are for understanding, not for swapping tools. Common traps ISMP describes:
tsp vs tbsp. The abbreviations look alike, and a tablespoon holds three times as much.
The whole cup. Some people assume the full cup is the dose, but ISMP says the entire cup typically holds up to 30 mL.
Faint markings. Some cups have measurements etched into the plastic, which are hard to see.
Mismatched units. Mistakes happen more often when the label lists teaspoons but the device is marked in mL.
ISMP recommends doses written in mL. If a label lists only teaspoons or tablespoons, ask the pharmacist to confirm the mL amount and to relabel a prescription medicine with it.
ISMP describes a study of more than 2,000 parents in which 99% measured at least one dose that wasn't exact. Errors were 4 times more likely with a dosing cup than with an oral syringe, especially for small amounts.
Oral syringe. ISMP calls it the gold standard when accuracy matters, ideally with mL markings only. If a medicine comes with a cup, you can ask the pharmacist for an oral syringe instead. MedlinePlus warns that the FDA has had reports of young children choking on syringe caps, so remove the cap before use and throw it away or keep it out of reach.
Dosing cup. Handy, but MedlinePlus notes dosing errors have occurred with cups. Check the units and read it at eye level.
Dropper. ISMP suggests checking that the markings are easy to see and understand. If not, ask the pharmacist for a small oral syringe.
Children. ISMP says to know a child's current weight, because the most accurate dose for children's over-the-counter liquids is based on weight, not age. The FDA says to follow age and weight limits on the label and call your doctor if the label says not to give it.
No guesswork. The FDA warns never to play doctor: a child who seems twice as sick doesn't need twice the dose.
Two medicines at once. Talk to your doctor or pharmacist before giving two medicines at the same time, to avoid a possible overdose or interaction (FDA). ISMP also advises measuring each liquid in its own device and not mixing medicine into food or drink unless the label says it's okay.
Older eyes and hands. Good light and reading glasses matter. Ask the pharmacist which device is easiest to read and hold.
Storage. ISMP suggests keeping adult and children's liquid medicines in separate places, all up and away out of reach. See our sister site's guide to storing medicine safely at home.
Pharmacist: the device is missing, the units don't match, or you're unsure. ISMP suggests asking for a demonstration, then showing the pharmacist how you'll measure each dose.
Doctor or pharmacist: new symptoms, unexpected side effects, or the medicine doesn't seem to work. The FDA says to talk to them right away.
Too much medicine: MedlinePlus says to call 911 or the Poison Help line at 1-800-222-1222 if you think someone has been poisoned, and not to wait for symptoms. Call 911 right away if the person has trouble breathing, has a seizure or can't be woken.
No. MedlinePlus says eating spoons vary from about 2.5 mL to 10 mL, and the FDA advises against substituting a kitchen spoon for the dosing device.
MedlinePlus lists 5 mL as 1 teaspoon and 15 mL as 1 tablespoon. Still, measure with the device marked in the units your label uses.
ISMP says to ask a pharmacist to recommend a device, and not to borrow one that came with a different medicine.
In the study ISMP describes, parents made errors 4 times more often with a dosing cup than with an oral syringe.
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Liquid medication administration (MedlinePlus, National Library of Medicine)
Safety Tips When Measuring Doses of Liquid Medicines (Institute for Safe Medication Practices)
Measurement Mishaps with Liquid Medicines (Institute for Safe Medication Practices)
Poisoning first aid (MedlinePlus, National Library of Medicine)