ST. AUGUSTINE BEACH, Fla. -

A St. Augustine Beach 20-year-old said he feels lucky to still have a leg after he was bitten by a water moccasin on Sunday.

It took 12 vials of antivenin to treat Jon Heater, who is back home after three days in the hospital.

Heater said he can't remember exactly when he was bitten. But after hours of his ankle swelling, he realized something was wrong.

Now he's home propping his leg up, and he said he's relieved he still has that leg to prop.

“It could have been a lot worse, walking around with no leg,” Heater said. “That wouldn't be any fun.”

Heater said that could have been the reality if he didn't get to the hospital Sunday, hours after he went fishing. His ankle, which is still swollen, started swelling up that day, and he said he thought he'd been bitten by a spider.

“But then the fang marks were so wide and it just was so bad,” Heater said. “Once I got to hospital, they took blood and I checked in and was definitely going to be a snake bite. They've seen it before. How puffed up it was, it looked just like what they'd seen with moccasins in the past.”

Doctors administered a dozen doses of antivenin to counteract the venom from the water moccasin that bit Heater.

“I can't get bit again or I'll die,” Heater said. “I can't have antivenin anymore. You're only allowed to have antivenin one time in your life, and I got 12 doses of it in the past three days, so if I get it again, they can't do anything to help me.”

As a result, Heater said he'll be more cautious for his next fishing trip.

“I don't know, I guess wear boots,” Heater said. “I just can't go barefoot around the water anymore.”

And Heater's not out of the woods yet. Doctors said they will be monitoring him for the next seven days because sometimes people can have a bad reaction to the antivenin.