Nearly 1.5 million Americans are severely allergic to even a trace of peanuts.
That allergy can cause hives, plunging blood pressure and swelling of the face and throat, which can be fatal.
A 15-year-old in Montreal died this week after kissing her boyfriend, who had eaten a peanut butter snack.
It's a product that many of us don't think twice about eating, a popular sandwich spread or snack at the ballgame.
For others, it can mean being on constant alert to avoid peanuts due to severe allergic reactions.
"Once that reaction gets triggered, the end result can be a fatality," says Dr. Martin Voss, a Luther Midelfort allergist. "Most of the time, the cause of death is closing off of the airway either upper airway or an asthmatic reaction or shock."
People with severe peanut allergies can have reactions based on traces of peanuts found on doorknobs, tables, anything that's been touched by someone eating peanut products or even passed along by particles in the air.
Eau Claire School District is seeing more students with the allergy and is taking steps to prevent deadly reactions.
"We're seeing more and more of them and we're taking more precautions," says registered dietitian Mary Paulson, who works for the district. "We have several schools where we have peanut-free tables where the children eat at that are completely peanut free."
Teachers and staff are trained to respond if reactions do occur. For the most part, Paulson says, schools menus are now peanut free.
"We've established a health council of registered nurses, teachers, administrators, registered dietitians to work on our plan."
A shot of adrenaline shuts down the reaction, and those who know they have the allergy carry one with them constantly.
"It'll stop the reaction," says Dr. Voss. "It also is the only drug that will reverse all the target organs causing you to have this serious response in your body."
New federal guidelines will require warning labels on foods containing peanuts starting next year.