It's a condition that can cause anxiety, isolation and -- in the worst of cases -- death. Childhood food allergies are a growing problem.
It's unknown exactly why the incidence of food allergies is increasing but for some parents, there is a way to lessen the risk.
Elijah Silvera was 3 years old when he died after eating a grilled cheese sandwich at day care.
"From that point on, it changed our family's life forever, pretty much," said Thomas Silvera.
Elijah, who lived in New York City, suffered numerous food allergies, one of them to milk products. Ingesting the grilled cheese sandwich caused Elijah to go into anaphylactic shock in November 2017.
"Severe food allergy is not something people just talk about. It's not a myth. It's not an old wive's tale," said Thomas Silvera.
Food allergies are increasing.
"Studies have shown repeatedly that there's a slow increase in prevalence of food allergies. I think it's a true increase in prevalence," said Dr. John Leung of Boston Food Allergy Center.
A new study in the Journal of Pediatrics estimates around 8 percent of children in the United States now have food allergies.
The most common include peanuts, milk, shellfish and tree nuts.
Peanuts lead the list of foods most likely to cause severe reactions, followed by tree nuts and shellfish.
But Leung says as children grow, some allergies go.
"Some of the food allergies are easy to outgrow. Milk and eggs are easier to outgrow than nuts and shellfish," said Leung.
But for some patients, there is even a way now to lessen the risk of those food allergies they don't outgrow through immunotherapy.
Elizabeth Saxe is undergoing treatment for her peanut allergy.
"It will be nice not to really have to worry about it. Not to have to ask at a restaurant about cross-contamination, that kind of thing," said Saxe.
Elijah Silvera's parents say awareness and education about food allergies is key to protecting other children.
They're working in their son's memory to get a law passed requiring food allergy policies and procedures in all day care centers in New York.
Elijah's father says his son's last words keep him going.
"Make a hand, make a hug, make a kiss... and that's how we continue to move forward," said Thomas Silvera.
Editor's note: A previous version of this story and headline indicated that about 80 percent of children have food allergies. The actual number is about 8 percent.