Parents are being warned to reduce the amount of parcetamol that they give their young chilren.
There is fears that they could be giving toddlers too much of the painkiller.
By the time babies are six months old, 80 per cent of them will have been given doses of liquid paracetmol, which is sold under brand names like Calpol, Disprol and Medised.
The new guidance divides children into four age groups from three months to six years old.
It says infants should receive 2.5ml up to four times a day, while those over four can get the full 10ml four times a day.
Previous guidelines stated that children under six could be given up to 40ml of liquid paracetamol per day, in four 10ml doses, to reduce pain and fever.
But the Medicines and Healthcare products Regulatory Agency found some children are being over-medicated on that advice.
In rare cases, high intake over a long period can lead to liver damage.