Spider bite toxicity and age?

I have what I believe to be a spider bite and at its worst it looked like a large yellow oval with a thin red ring around it. I have been seeing many brown recluse spiders recently and have had a small one (about the size of my pinky fingernail) that has been crawling around my wall and ceiling near my bed. I know that a brown recluse bite would have been much worse than that so I was wondering if the age of a spider affects the toxicity of its bite.