"We thought we were going to lose him. He stopped breathing. By the time the paramedics got to him, his heart had stopped," she said.
So in preparation for Nicolas starting pre-school, Carolyn gave administrators a list of 19 strict requirements to keep him safe.
They included prohibiting food-trading among children, making children wash their face and hands after eating and insuring a teacher carries a life-saving shot of epinephrine wherever Nicolas goes.
"If he has a reaction, this is what they'll use. This is basically adrenaline," she said.
The school suggested that perhaps Nicolas should stay home.
Carolyn read from a letter from the school: "Nicolas' condition would pose a significant threat to the health of the other children and staff of the program."
"It's heartbreaking to receive a letter like that," she said.
Melissa Hopper knows what Nicolas is going through. Peanut oil nearly killed her at age 14
"It was an awful experience. I was turning blue from lack of oxygen," Hooper said.
When she dines out, Melissa takes no chances and demands the restaurant screen her food for nuts of any kind hidden in sauces, flour or oil.
Of the two million American children and adults who have nut allergies, more than 100 suffer fatal allergic reactions each year. Dr. Hugh Sampson says even the tiniest amount can be deadly.
"If they have a very severe reaction they will actually develop a drop in their blood pressure and they will lose consciousness," Sampson said.
This can happen in just a couple of minutes.
New hope for people with peanut allergies may come from experiments being conducted at Sampson's lab at the Mount Sinai Medical Center in New York. They are working on a vaccine against peanut allergies.
"We're sensitizing the mice so that they'll develop an allergic reaction to peanut, much like you'd see in a human," Sampson said.
So far, experiments with the vaccine in mice have been promising. Sampson hopes to try it in humans within two years - and take away the anxiety so many peanut-allergic people suffer.
"Our whole society is so involved in eating. Every social event we go to involves eating. And for these people, it's a nightmare," he said.
The nightmare has already eased a little. Manufacturers have begun to process food with nuts on separate machines to avoid cross-contamination. Some school districts have banned peanut butter all together.
And after a seven-hour meeting with Nicolas' school, Carolyn Lengua hopes the battle is over.
"It took a while to convince the school that all we wanted to do was keep him safe," she said.
Even with the strictest of precautions, until a vaccine is perfected for Nicolas, Melissa and many other, peanuts will remain as deadly as poison.
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