(CNN) - Stephanie Mellom was bitten by a poisonous spider while she slept but she didn't know it.
"I felt a bump on my chest and I thought it was just like a bump you have on your face," Mellom said.
When the bite got bigger, painful and read, she went to the doctor. She was experiencing some classic symptoms of a poisonous brown recluse spider bite.
This species, known for the violin shaped brown mark on its back, and the black widow, most easily identified by an hourglass red mark on its belly, are the two types of spiders dangerous to humans in the United States.
Fortunately, their bites are rarely lethal.
According to Dr. Keith Jeffords with Paramount Plastic Surgery, "The distinguishing factor between a pimple and a spider bite would be puss."
He said pimples and infections will create puss, but spider bites will not. While the venom does not often kill, it can still be dangerous.
"It destroys the skin tissue, the superficial skin tissue," said Dr. Robert Geller of the Georgia Poison Center at Emory University, "and what you see is, it looks like a severe burn almost."
A bite from either poisonous spider can also cause fever and nausea. Black widow venom usually brings on severe abdominal pain as well. Fortunately, medications are available to treat both kinds of bites.
It's been six weeks for Stephanie and she's finally feeling better.