ORLANDO, Fla. -

"Red touch yellow, kill a fellow. Red touch black, just step back."

It's the rhyme taught to Florida children in hopes of keeping them safe from coral snakes.

But by the end of this month, the only medical way to protect them from danger for certain may no longer exist.

The nation's entire supply of coral snake anti-venin is set to expire on December 31, 2012.

A coral snake doesn't strike, it gnaws.

As it chews, it slowly releases a venom, so toxic, it can seize the nervous system and stop you from breathing in a matter of hours.

To look at Zachary Mazzocci now, you'd never know his young heart stopped beating not once, but twice the day he was bitten by a coral snake.

Zachary was airlifted from his hometown of Naples to Miami-Dade children's hospital where the venom team took immediate action.

“They had never experienced such a young kid getting bit by a coral snake. They started by 5. They thought 5 might be enough,” said Louis Mazzocci, Zachary’s father.

Mazzocci is talking about anti-venin.

Five precious vials doctors injected into his son, but it would take double that amount to finally stabilize the boy.

“When I walked up and saw him for the first time, I can't even put it into words, to see your child like that is one of the most painful things,” said Michelle Mazzocci, Zachary’s mother.

She knows her son would not be here today, racing down the roadway on his bike, without that anti-venin.

"It saved my son's life without a doubt. A coral snake kills you in an hour and a half,” said Mazzocci.

But because coral snake bites are relatively rare, an average of 100 per year in the United States, drug company Wyeth said it was no longer profitable to make and quit manufacturing it in 2003.

The bite numbers in Florida alone accounts for nearly half of the annual bites and poison control calls Central Florida a "hot bed."

Now, the final batch is set to expire in just four weeks.

“They have continued to study the existing lots to see if there is a safe and effective way to extend the expiration,” said Dr. Josef Thundiyil, a medical toxicologist at Orlando Regional Medical Center.

But that's not a guarantee. Thundiyil says the dwindling supply is already affecting the way snake bite victims are treated.

“The more we know and the more that there's a shortage, we are as cautious as we can, use as little as we can to still be effective,” said Thundiyil.

Sometimes, with only a few hundred vials left in the nation, the victim must go without.

“What we'd see without anti-venin is a more severe reaction and a more prolonged course,” said Thundiyil.

Something Zachary's father believes should never happen.

“It's bad because people are going to die, over what, they don't want to make it because it's not profitable for them?,” said Mazzocci.

The Food and Drug Administration is investigating whether anti-venin used in other parts of the world are safe enough to be used in the US.