Wondering if your food allergies have changed? Try a food challenge


August 20, 2021

With the help of an allergist, you can safely assess if you no longer have food allergies and whether you can add a food back into your diet.

Food allergies can be a source of fear and anxiety in many dining situations and can hinder nutritional options. If you’ve been living with one or more food allergies after a negative reaction in the past, a food challenge — under the guidance and observation of your allergist — can reveal whether the issue has changed.

“Your immune system changes over time,” said Basil Kahwash, M.D., an allergist and immunologist with the Vanderbilt Asthma, Sinus, and Allergy Program. “So a lot of people who have allergies in childhood are going to outgrow them because your immune system matures. It starts to learn that not everything that it was previously recognizing as a threat is a threat.”

Outgrowing food allergies

Unfortunately, about 80% or more of kids don’t outgrow a peanut, tree nut, or shellfish allergy, Kahwash said. But kids who have milk, egg or wheat allergies very commonly outgrow those allergies.

Food challenges

Testing for a food allergy often starts with a skin or blood test. If your skin or blood test shows that you’re not allergic, or if the test is inconclusive but the allergy team is confident you won’t have an allergic reaction, you’ll move on to the next step. “That’s when you need the food challenge to really settle it once and for all,” Kahwash said.

In some cases, the food challenge can take place at home. “If the history is really unconvincing,” Kahwash said, “as in they had a reaction but it doesn’t really sound like an allergic reaction and all of their testing is negative, then we tell them to go home and try the food at home — you’re almost certainly not allergic.”

If someone has a history of allergic reaction, but their skin or blood test seems to suggest they may have outgrown the allergy, then the food challenge is performed in the clinic under careful observation.

“If you start to have a reaction,” Kahwash explained, “we have everything ready to treat you. And we have people in our office who have done hundreds of these challenges in the past and who are trained to recognize the early signs of an allergic reaction.”

Anaphylaxis, which is a severe allergic reaction, is rare during a food challenge, Kahwash said. “We start with very small quantities,” he explained, “and then we increase the quantities to a full serving to really prove that somebody is not allergic.” If a reaction does occur, typically it’s mild and caught early. Mild reactions can be treated with supportive care or antihistamines.

Some people will not be able to move forward with a food challenge after a skin or blood test because of the risk. But Kahwash said the allergy should continue to be monitored in case it changes and a food challenge becomes a viable option.

The importance of food challenges

“One of the most satisfying things I do is tell someone they’re not allergic anymore and can reintroduce the food into their diet.”

“The food challenge can be really great for both nutrition and for quality of life,” Kahwash explained. “The fewer things that you’re allergic to, the more you’re able to extend your diet.”

Also, food allergies can create anxiety when dining out or visiting someone else’s home for a meal. Removing that allergy when possible can eliminate that fear. “One of the most satisfying things I do,” he said, “is tell someone they’re not allergic anymore and can reintroduce the food into their diet.”


Allergies, asthma and sinus problems can produce similar symptoms, ranging from annoying to life-threatening. The Vanderbilt Asthma, Sinus and Allergy experts give you an accurate diagnosis and treatment tailored to you, your symptoms and your life. Vanderbilt Asthma, Sinus and Allergy has five locations in Middle Tennessee: Nashville, Brentwood, Franklin, Gallatin and Lebanon.

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