A drug that has been used for decades to treat allergic asthma and hives significantly reduced the risk of life-threatening reactions in children with severe food allergies who were exposed to trace amounts of peanuts, cashews, milk and eggs.

A drug that has been used for decades to treat allergic asthma and hives significantly reduced the risk of life-threatening reactions in children with severe food allergies who were exposed to trace amounts of peanuts, cashews, milk and eggs, researchers reported Sunday.

The drug, Xolair, has been approved by the Food and Drug Administration for adults and children older than the age of 1 with food allergies. It is the first treatment that drastically cuts the risk of serious reactions — such as anaphylaxis, a life-threatening allergic reaction that causes the body to go into shock — after accidental exposures to various food allergens.

The results of the researchers’ study on children and adolescents, presented at the annual conference of the American Academy of Allergy, Asthma and Immunology in Washington, were published in The New England Journal of Medicine.