Daughter was bitten by a brown recluse when she was young (6-7ish) and because she was so small (prob. 50lbs or under) the poison didn't stay at the bite, but spread throughout her body via. her lymphatic system.
Quick trip to the hospital, and couple doc visits and she was just fine. We left a week later to go on a vacation.
Day 2 of said vacation the bite area got infected, and due to the damage done by the recluse a massive infection spread throughout her body. We got to spend 4-5 days in the St. Louis Jewish Hospital (kudos to them, top-notch place) and eventually she was ok.
So the bite isn't what did it, it was the infection that spread due to the damage the poison causes.
To this day I shake out my shoes and clothes before I put 'em on. Nasty little buggers.
(Official member of the "kill the brown recluse with extreme prejudice club)