Fever in Children: Dose Paracetamol by Weight, Not by Age

Two bottles of paracetamol syrup sit side by side on a pharmacy shelf. Same brand, same colour, nearly the same label. One is 125 mg per 5 ml. The other is 250 mg per 5 ml, usually marked "DS" or double strength. Give the same 5 ml spoon from the wrong bottle and your child has received twice the intended dose.

This is not a rare mistake. It is one of the most common paediatric medicine errors reported anywhere, and it is entirely preventable with one habit: read the strength, and dose by weight.

Why age-based dosing is unreliable

Cartons often print a rough age guide, and it is a poor guide. A well-grown three-year-old can weigh twice what an underweight three-year-old weighs. The medicine does not know how old your child is; it distributes through body mass.

The standard paediatric dose of paracetamol used by doctors is 15 mg per kg of body weight per dose, repeated no more often than every 4 to 6 hours, with a maximum of four doses in 24 hours. Work out the millilitres once, write them on a slip of paper, and keep it inside the medicine box.

To convert that dose into millilitres:

• With 125 mg/5 ml syrup: millilitres = weight in kg × 0.6
• With 250 mg/5 ml (DS) syrup: millilitres = weight in kg × 0.3

So a 10 kg child needs 150 mg — that is 6 ml of the 125 mg/5 ml syrup, or 3 ml of the 250 mg/5 ml. A 20 kg child needs 300 mg: 12 ml of the regular strength, 6 ml of the double strength. Confirm the figure with your paediatrician, and re-check it every few months, because children gain weight fast.

Two other forms need care. Paediatric drops are far more concentrated and come with their own dropper, and suppositories are dosed differently again. Never carry a millilitre figure from one form to another. The pages for paracetamol 125 mg/5 ml and paracetamol 250 mg/5 ml are listed separately for exactly this reason, as is our full syrups and suspensions section.

Use the right measuring device

Kitchen teaspoons are not a unit of measurement. Household spoons in Indian homes range from roughly 3 ml to 7 ml, which means a "spoon" of syrup can be half or one and a half times the intended dose.

Use the measuring cup, dropper or oral syringe that came in the box. For small volumes an oral syringe is the most accurate, and it also lets you give the dose slowly into the cheek of a child who fights the cup. Rinse and dry it after every use, and keep each medicine's device with its own bottle — droppers are not interchangeable between products.

Shake suspensions well before pouring, too. The active drug settles at the bottom, so an unshaken bottle gives weak doses at the start of the bottle and unexpectedly strong ones at the end.

Treat the child, not the thermometer

Fever is a symptom, not a disease. It is the body's response to infection, and at the levels seen in ordinary childhood illness it is not in itself damaging. The purpose of paracetamol is to make an uncomfortable child comfortable — able to drink, rest and sleep — not to force the number down to 98.6°F.

A child with a temperature of 101°F who is playing, drinking and reasonably cheerful may not need medicine at all. A child at 100.4°F who is miserable and refusing fluids probably does. Watch the child.

For measuring, a digital thermometer is the practical choice at home. Under-arm readings run slightly lower than oral ones, and forehead and ear thermometers are convenient but more sensitive to technique. Whichever you use, use the same one consistently so that you are comparing like with like — our thermometers and nebulisers section lists the types side by side. Mercury-in-glass thermometers are best replaced; a broken one is a mercury spill in a child's room.

When to stop managing at home and see a doctor

Call a doctor or go to hospital if:

• The child is under 3 months old and has any fever at all. This is an emergency, no exceptions.
• Fever has lasted more than three days, or keeps returning after settling.
• There is difficulty breathing, fast breathing, or the chest is drawing in with each breath.
• The child is unusually drowsy, difficult to wake, or inconsolably irritable.
• There is a seizure, a stiff neck, or a rash that does not fade when pressed with a glass.
• There are signs of dehydration — no urine for many hours, no tears when crying, a dry mouth, or a sunken soft spot in an infant.
• The child has a chronic condition or is on medicines that suppress immunity.

In the dengue season, one point deserves emphasis: avoid ibuprofen and other NSAIDs, and avoid aspirin, when dengue is suspected, because they affect platelets and bleeding risk. Paracetamol is the fever medicine of choice unless a doctor says otherwise. Aspirin should not be given to children with a viral illness at all.

What not to do

• Do not alternate paracetamol and ibuprofen on your own. Some doctors advise it in specific situations; done casually at home it is the fastest route to a dosing error, because two schedules, two strengths and two measuring cups get mixed up.
• Do not use cold water, ice or alcohol rubs. Cold sponging makes a child shiver, which raises core temperature, and alcohol can be absorbed through the skin. Lukewarm sponging is the safe version.
• Do not over-wrap a feverish child in blankets, and do not give a combination cough-and-cold syrup that already contains paracetamol on top of a separate paracetamol dose. Read every label for a hidden second source of the same molecule — this is the commonest cause of accidental overdose.
• Do not give leftover antibiotics from a previous illness. Most childhood fevers are viral, and antibiotics do nothing for them — see why an antibiotic course has to be finished.
• Do not keep medicines where a child can reach them. Paracetamol overdose in children is usually accidental self-administration of a sweet-tasting syrup. Store the bottle high, capped and out of sight — and in Indian summers, out of direct heat, as covered in storing medicines safely.

Keep a simple record

During an illness, write down the time and amount of every dose. When a child is being looked after by more than one adult through a long night, "did anyone already give her the syrup?" is a genuinely dangerous question. A written line on the back of the carton settles it in a second and prevents a double dose.

Fever in a child is frightening, and the instinct is to do something. Most of the time the right something is small: fluids, rest, the correct dose measured properly, and a clear list of the signs that mean it is time to stop watching and go.