Because children generally do not outgrow peanut allergies, they must avoid peanuts, peanut oil and foods contaminated with traces of peanuts for their entire lives.

More than a dozen parents traveled to the hearing in Silver Spring, Md., with their children to urge the advisory committee to approve the drug, often breaking into tears as they spoke. They recounted how their children’s lives had changed after they took part in the study. (The company paid travel expenses for some of the families.)

Guiliana Ortega, w ho participated in the Aimmune study, described life as an 8-year-old with a severe peanut allergy: sitting at a separate peanut-free lunch table in the cafeteria, for example, and having to ask relatives if they have eaten peanuts before giving them a hug.

“It means getting only two friends at lunch instead of 20,” she told the committee. “It means not getting to eat cake at parties, and eating my safe snack while watching others enjoy it.”

“It means feeling different all the time,” she said. “It’s a world of no. ‘No, you can’t have that — it may not be safe.’”

Tessa Grosso, 16, a high school junior from Menlo Park, Calif., told the panel she was allergic to peanuts, dairy and many other foods until she was 10, when she was treated with an early form of oral immunotherapy at Stanford University.

Now, she said, she eats just about anything and has peanut butter every morning before school.

“Before I was treated, my life was like navigating a minefield,” Ms. Grosso said in an interview. “I couldn’t go to anyone’s house, and a crumb of something on my hands could have killed me. At one point, a glass of milk spilled on my hand and I went into anaphylactic shock and almost died.”