The first time Amber Chen tried Reese's Pieces, she had an anaphylactic allergic reaction to the peanuts in the candy.

SOUNDBITE (English) REPORTER SAYING: "Can you eat them?"

AMBER CHEN, PEANUT ALLERGY SUFFERER, SAYING: "No."

REPORTER SAYING: "Why not?

AMBER CHEN, PEANUT ALLERGY SUFFERER, SAYING "Because I'm allergic."

Four year old Amber is one of roughly 2.8 million Americans with a potentially life-threatening allergy to peanuts.

Anaphylaxis can cause difficulty breathing, swelling of the tongue, eyes or face; vomiting, and in some cases death.

Amber's mom Heather Sapp knows what to watch for.

(SOUNDBITE) (English) HEATHER SAPP, MOTHER OF PEANUT ALLERGY SUFFERER, SAYING:

"She gets a runny nose, then she starts complaining about her tummy, all things that, you know, kids get. You wouldn't think it was anything other than just the flu. But pretty soon after that, she starts developing hives, then her face starts swelling, then s