More than half of all three year olds in America are currently taking an over the counter (OTC) drug, even though some can cause serious side effects, especially if taken with prescribed drugs.

The most common were treatments for coughs and colds, such as Tylenol, which had been given to 35 per cent of small children.

But doctors are worried that the drugs are not being given properly, while the efficacy of cold remedies was the focus of a recent congressional hearing during which the chairman described them as "hype", rather than healthcare. As a result, parents may be needlessly exposing their children to toxicity.

The consumer group Health Action International is calling for tighter controls of OTC advertising. An international study it carried out discovered that 87 per cent had no information

of side effects, and 84 per cent mentioned no contraindications.

The American study, carried out by the Centers for Disease Control and Prevention among a nationally representative sample of 8,145 women, discovered that nearly 54 per cent of mothers of three year olds had given their children some OTC drug in the last 30 days. The findings are similar to studies carried out in the UK.

Other common OTC medications given to children included analgesics (4 per cent), treatments for diarrhea (3 per cent) and aspirin (1 per cent). The use of aspirin was, in the main, among less educated and unmarried mothers who may not be aware of the dangers of the brain disorder Reye's syndrome, which can be caused by the drug.