Here's a link to the WedMD. It has some good information on it. Page 4 shows pics of how quickly the damage occurs.

http://www.webmd.com/a-to-z-guides/brown-recluse-spider-bite

When I was bit in the underarm area by one, I ran a fever. I was at a wedding reception and noticed that I couldn't raise my arm when dancing. It was too painful. I was given antibiotics and some type of cream to put on. It was years ago. I remember the smell of dying flesh. I was lucky that my bite damage was stopped.

My father was bitten two different times. He had to have surgery both times. He had been put on antibiotics and pain pills.
They ended up having to cut the dead tissue away both times. He has two holes in his thigh now. The poison from the bite causes the tissues of our bodies to basically rot. It spreads like an ulcer.

My Dad is fanatical about getting his house and car exterminated regularly now. He's thinking that there's a chance he got bit in his car.

Cool, huh?

Basically, there is no treatment known to established medicine.

Ugly thing.

They're also very difficult to get rid of because they are reclusive.
They hide more then other spiders. They're very small too. I've known people that have moved because they can't get rid of them.