Some of the most popular children’s medicines contain E numbers that have been withdrawn from food and drink products because of links to hyperactivity in children.

Products from leading brands such as Calpol and Boots are among 52 children’s medicines that have at least one of the “Southampton Seven” – a group of additives that were proven to increase hyperactive behaviours in a landmark study five years ago.

In 2008, the Food Standards Agency imposed a “voluntary ban” on the six E number colourings included in the Southampton study, a move which led most supermarkets and food manufacturers to withdraw them. Synthetic colourings in food and drink targeted at children under 36 months old are subject to a European ban.

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However, medicines fall under a different regulatory regime, and the substances are still commonly found in products for children. An investigation by the campaign group Action on Additives found that four of the six colourings – quinoline yell (E104), sunset yellow (E110), carmoisine (E122) and Ponceau 4R (E124) – are used in children’s medicines, including products for infants as young as two months. It called on the Medicine and Healthcare Products Regulatory Agency (Mhra) to ban the additives from food and medicines altogether.

“We’re not advising parents not to buy these medicines,” the group’s spokesman, Lizzie Vann Thrasher, told The Independent. “But if these additives have been taken out of food and drink for all children under 36 months, and there’s been a recommended withdrawal in food and drink for older children, why do we still have them in children’s medicines that can be given to children as young as two months old?”

The agency said it was aware some additives could cause “an unwanted reaction”, and urged parents to report concerns about medicine safety.

A three-year study carried out at the University of Southampton found that children who were given fruit drinks containing a mixture of the seven additives showed higher signs of hyperactivity – including fiddling with objects, changing their activity, and interrupting, than children who were given a placebo. On average, the children displayed 10 per cent of the level of symptoms of a child diagnosed with attention deficit hyperactivity disorder.

Manufacturers and the regulatory body pointed out that the quantities of the additives ingested via medicines would be comparatively small compared to food. But Ms Vann Thrasher said a normal dose of Calpol taken over several days amounted to a third of the level of additives used in the Southampton study.

Johnson & Johnson, makers of Calpol, said: “Carmoisine (E122) and sodium benzoate are contained in many medicines which have been approved for use by the Mhra in the UK.”

Boots said: “The colourants and other additives that have been mentioned are commonly present in medicines which have been approved for use by the Mhra... one of the Mhra’s roles is to assure that colour and other additives used in medicines are safe and that the products containing these ingredients are appropriately labelled.”

Dr Sui Ping Lam, the Mhra’s acting director of licensing, said: “The quantities used in, and consumed from medicines is […] comparatively small compared to foods.

“We encourage anyone who has had an adverse reaction to report it to us through our Yellow Card reporting Scheme.”

A Food Standards Agency spokesman said: “It is important to remember that hyperactivity is also associated with many other factors in addition to certain additives, so dietary advice may help manage hyperactive behaviour, but may not be the total solution.”