WASHINGTON — A further shakeup in the marketplace for cold and cough medicines used billions of times each year in treating the youngest children is likely, as government health advisers weigh options from an outright ban to more study.

The Food and Drug Administration expects a recommendation from the joint panel of outside experts late today, at the conclusion of a two-day meeting. Its purpose was to determine whether the widely used over-the-counter medicines are safe and work in young children.

The drug industry says the medicines, used 3.8 billion times a year in treating cold and cough symptoms in children, do work and are safe, but agrees more parent education is needed to avoid rare but fatal overdoses.

Pediatricians pushing for greater restrictions in how the medicines are marketed to parents insist the medicines not only don’t work but can be dangerous as well.

Those doctors told FDA advisers yesterday that the over-the-counter medicines shouldn’t be given to children younger than 6. Such a prohibition would go beyond last week’s drug industry move to eliminate sales of the nonprescription drugs targeted at children under 2.

Some of the drugs — which include Wyeth’s Dimetapp and Robitussin, Johnson & Johnson’s Pediacare and Novartis AG’s Triaminic products — have never been tested in children, something flagged as long ago as 1972 by a previous FDA panel. An FDA review found just 11 studies of children published over the last half-century. Those studies did not establish the medicines work in those cases, according to the agency.

The panel also is being asked to examine whether the dizzying array of medicines that combine multiple ingredients and the sometimes hard-to-use droppers included in the packaging contribute to parents unwittingly overdosing their children. Some in the FDA recommend doing away with the combo products and requiring better designed and standardized dosing devices.

The FDA isn’t required to follow the recommendations of its advisory panels, but does so most of the time.