A medication used to treat asthma can now be used to help people with food allergies avoid severe reactions, the U.S. Food and Drug Administration said Friday.

Xolair, the brand name for the drug omalizumab, became the first medication approved to reduce allergic reactions caused by accidental exposure to food triggers. Patients as young as age 1 with allergies can take the drug by injection every two to four weeks, depending on their weight and their body’s response to allergens.

An estimated 17 million people in the U.S. have the type of food allergies that can cause rapid, serious symptoms, including severe, whole-body reactions that are potentially deadly.

People who use Xolair must continue to avoid the foods that cause them reactions, such as peanuts, cashews, hazelnuts, walnuts, milk products and eggs. The medication allows them to tolerate higher amounts of such foods without causing major reactions.

Many people with allergies — and their families — live with constant anxiety about exposure to allergens and often avoid dining out and other social situations.

“To have this protection is going to be life-changing,” said Dr. Robert Wood, director of the pediatric allergy division at Johns Hopkins Children’s Center.

The FDA decision is based on a study led by Wood and funded by the National Institutes of Health. It showed that Xolair allowed about 68% of participants with peanut allergies to tolerate about 600 milligrams, or about 1/2 teaspoon, of peanut protein, compared with about 6% of those who received dummy injections.

The results were similar for other allergens such as tree nuts, milk, egg and wheat, a study abstract reported. Full results are expected to be presented at a meeting and published in a peer-reviewed journal later this month.

Wood estimated that 25% to 50% of people with food allergies, particularly children and young adults, would elect to use Xolair.

The drug has been used “off-label” to treat food allergies, said Dr. Ruchi Gupta, director of the Center for Food Allergy & Asthma Research at Northwestern University. She welcomed full approval of the product.

Xolair is a monoclonal antibody, a type of treatment that works by blocking the body’s natural response to allergens. It was first approved in 2003 and has been used to treat asthma, nasal polyps and chronic hives. It is produced by drugmakers Novartis and Roche and is distributed by a Roche subsidiary, Genentech.

The most common side effects of Xolair are injection site reactions and fever, but the FDA noted that the drug has also been associated with joint pain, rash, parasitic infections, malignancies and abnormal laboratory tests. Xolair comes with a warning saying the treatment itself can cause anaphylaxis and must be started in a health care setting equipped to manage the reaction.

The medication is not approved for emergency treatment of allergic reactions.

The list price for Xolair ranges from about $2,900 a month for children to $5,000 a month for adults, according to Genentech. Most insured patients typically pay less out of pocket, the company said.

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