(Reuters Health) - Oral food challenges at the doctor’s office are a safe way to diagnose food allergies, a U.S. study suggests.

Based on records of more than 6,000 food challenge tests done in allergy practices in Houston, Pittsburgh, Seattle, Boston and Indianapolis, researchers found that only 2 percent produced a severe allergic reaction known as anaphylaxis.

Across practices, just 13 percent to 33 percent of patients had any type of allergic reaction.

In oral food challenges, patients consume a very small amount of food by mouth while doctors watch for an allergic reaction.

“Parents should know it’s safe in a clinic with a physician that’s skilled in performing oral food challenges,” said senior study author Dr. Carla Davis, a pediatric allergist at Texas Children’s Hospital in Houston.

Oral food challenge is the current gold standard for food allergy testing, she told Reuters Health by phone. “We don’t have another test that very accurately lets us know if a person is going to react to food if they eat it. The food challenge, unfortunately at this time, is the only way to determine if a person has a life-threatening food allergy or not.”

Past research has mainly focused on experiences at individual allergy clinics, Davis and her colleagues write in the Annals of Allergy, Asthma and Immunology. To get a broader picture of the safety of oral food challenges across the U.S., they examined records from five practices over a five-year period.

All tests were performed under the guidance of medical professionals. Most of the patients were under age 18.

Just 2 percent of those being tested experienced anaphylaxis, which requires immediate medical intervention. About 14 percent had mild or moderate reactions such as hives on the skin and were usually treated with antihistamines.

Davis said that if parents suspect their kids have food allergies, the best place to start is with their local allergist.

“They can also see their primary care physician because primary physicians can talk with them about symptoms as well as possibly do some screening laboratory tests to see if they need to go to an allergist,” she said.

Typical symptoms of allergic reactions to food include coughing or wheezing, vomiting and abdominal pain, hives, skin swelling, lip swelling and throat tightness, she said.

“A medically supervised feeding test (oral food challenge) is the most definitive type of allergy test,” said Dr. Scott Sicherer, a pediatric allergist at Icahn School of Medicine at Mount Sinai in New York City.

“When the medical history and tests such as blood and or allergy skin tests cannot provide sufficient evidence that a food allergy is present or absent, an oral food challenge can provide the answer,” said Sicherer, who wasn’t involved in the study.

The test food is given very gradually, in increasing amounts, and if the feeding is tolerated then the food can be added to the diet, he said.

“If symptoms develop, the testing is stopped and any treatment is given if needed to reverse symptoms. The test has to be conducted by trained personnel . . . because the test can trigger a severe allergic reaction,” Sicherer said by email.

This study reassures about the safety of the procedure, he added. “This is a very necessary and often underutilized test because it gives such important information that can be life-changing.”

Still, Sicherer cautions, the test is not without serious risks. “The report includes primarily children deemed already to be unlikely allergic, and was conducted in centers that are very experienced,” he said. “The input and supervision of experienced allergists is key to promote safety.”

SOURCE: bit.ly/2x2wy2s Annals of Allergy, Asthma and Immunology, online September 7, 2017.