Is it possible to get bitten by a black widow or brown recluse spider and not know it? i've seen a few in my house before, can they kill me?

Not likely: It is hilly doubtful you saw both of these spiders, but not impossible. They can inflict quite a bite, usually not deadly, but with serious consequences that require medical intervention. If you think you have them in the house, have a professional exterminator deal with the problem. Good luck from nyc.

No: You may not see the spider but you will see the effects. Brown recluse is a small siper, light brown with a violin looking belly. It injects a fat dissolving toxin which creates an enlarging ulcer. Black widow injects a neurotoxin which will affect the brain and can put you in coma. Get pest control an undust your house.

You would know it,: If you were bitten, because both of these spiders have toxins with obvious effects on humans.