Children under 2 years old should not be given over-the-counter cough and cold medicines because they are too dangerous for that age group, US health authorities have advised.

Deaths, convulsions and rapid heart rates have been reported in rare cases in children younger than two, the Food and Drug Administration said.

"We strongly recommend that over-the-counter cough and cold products should not be used in infants and young children under two years of age because serious and potentially life-threatening side effects can occur," Dr Charles Ganley, head of the FDA office that reviews nonprescription drugs, told reporters.

Ganley said the medicines "have not been shown to be safe or effective in children under 2" and noted they treat only symptoms and will not cure a cold.

The agency has not yet decided if the widely sold medicines made by companies such as Wyeth and Johnson & Johnson are appropriate for children of other ages. Officials are evaluating data on use in kids ages 2 to 11 and hope to rule by spring, Ganley said.

The cough and cold remedies have been sold for decades, but the FDA generally has not required companies to prove they work for children. Instead, data were extrapolated from adults.

"Children metabolise and react to medications differently than adults, often in unanticipated ways," the American Academy of Pediatrics said in a statement.

"Studies have shown cough and cold products are ineffective in treating symptoms of children under six years old and may pose serious risks," the group added in endorsing the FDA's move. - Reuters