Liquid Medicines: Why the Dose Is in Milligrams and the Spoon Is Not a Measure

"Give him a teaspoon" sounds like a dose. It is not. A dose of medicine is an amount of substance, in milligrams; the syrup is a way of carrying it, and how many milligrams sit in one milliliter is printed on that particular bottle. A kitchen teaspoon holds anything from 3 to 7 ml, and the same 5 ml from a different bottle can be a different dose. That is why the syringe in the box is not packaging: it is the only part of the system that measures.

When to see a doctor

Right away: fast or labored breathing, blue lips, seizures, a rash that does not fade under a pressed glass, a child who is hard to wake, any fever in a baby under twelve weeks (CDC, US; NHS, UK) — the medicine is not the question then. Also right away, even if the child seems fine: any suspicion of an extra dose of paracetamol — milliliters confused with milligrams, a second parent who already gave one, a cold remedy that also contained it. Also right away if you are not sure how much was given over the day. Overdose shows no symptoms for hours, and the antidote works best early (NHS, UK). Call the emergency number or the poison line: 112 in the EU and Russia (103 also reaches an ambulance in Russia), 911 in the US and Poison Help 1-800-222-1222, 999 in the UK and 111 for advice, which is also where an extra dose of ibuprofen goes (NHS).

The same day: the child will not drink, or a fever runs past the thresholds on the first signs of a cold.

Routinely: a child who takes a liquid medicine regularly — ask the doctor for the dose written down in milligrams and in milliliters for this bottle's strength.

What is happening

Parents measure badly, and cups make it worse. In a randomized experiment with 2,110 parents, 84 percent made at least one error across nine measured doses and 21 percent made at least one large error; errors were far more likely with a dosing cup than with an oral syringe, an adjusted odds ratio of 4.6 (Yin et al., Pediatrics 2016). The American Academy of Pediatrics concluded in 2015 that liquid medicines should be dosed only in milliliters, never in teaspoons or tablespoons, and dispensed with a metric syringe.

The same drug comes in different strengths. In the US, infant paracetamol used to be sold as concentrated drops of 80 mg per 0.8 ml next to a children's syrup of 160 mg per 5 ml; confusion between the two caused overdoses, some fatal, and in 2011 manufacturers moved to the single 160 mg/5 ml strength for both. Ibuprofen still has two: children's 100 mg/5 ml and infant drops of 50 mg per 1.25 ml. In the UK, paracetamol syrup comes as 120 mg/5 ml for infants and 250 mg/5 ml from age six. In Russia, Children's Panadol is 120 mg/5 ml and Nurofen for children is 100 mg/5 ml. The milliliters in a table only mean something next to the strength the table was written for.

Milligrams come from weight. The dose is calculated from body weight; age tables are a stand-in for weight where it is not known. US Drug Facts and Russian leaflets give both, the NHS gives age. The conversion is arithmetic: milligrams needed, divided by milligrams per milliliter on the label, equals milliliters to draw up.

What to do

Shake the bottle first. Suspensions settle; an unshaken dose is the wrong dose even when the volume is right (Russian Nurofen leaflet; NHS).
Use the syringe or spoon that came with this bottle. Not a kitchen spoon, not the syringe from another medicine, not a cup if a syringe is available (AAP; NHS; FDA).
Read the strength on the label before every bottle, especially a new one, a different brand, or a bottle bought in another country.
Dose by weight if you know it; otherwise by the age table on this leaflet — never by a table remembered from a different product.
Write down the time and the dose, and make one adult the dosing person for the night.
Keep the medicine in its box with its leaflet and its syringe. Do not decant into another bottle.
Rinse the syringe with warm water and dry it out of the child's reach (Russian Nurofen leaflet).

When this is not the case

Adult liquid medicines follow the same logic, and so do rehydration salts: a sachet is dissolved in the volume printed on it, and a stronger solution is not a better one — see dehydration and oral rehydration. Some prescription liquids come with their own device calibrated in units other than milliliters; there the pharmacist's instruction wins. And the arithmetic only helps if the milligrams are right for this child, which is the subject of paracetamol and ibuprofen doses for children. Why the brand name tells you none of this: the active ingredient.

Sources

Checked: September 7, 2026