Fortunately, when discussing the symptoms of spider bites, it can be said that the majority of Spiders do not have mouths large enough to penetrate human skin, which means that they cannot actually bite a human. In the United States, however, there are two spiders whose bites can penetrate the human skin and can be deadly if left untreated due to the poison in the spider's venom. The black widow spider and the brown recluse spider are the two most poisonous spiders located in the US. If you think you've been bitten by one of these dangerous spiders, you need to check your symptoms and seek medical attention right away. Both the black widow and the brown recluse are more common in the southern United States than anywhere else. They live in warm, dry areas where they can go undisturbed, such as piles of wood, basements, attics and even underneath the sink. Closets are also a common place where they spend time. When you have been bitten by a black widow spider, the bite feels like a pinprick, although you may not feel the spider bite you immediately. You will notice two fang marks at the location of the bite and you will experience immediate localized pain, redness and burning that accompanies swelling. Seek medical attention immediately. When bitten by a brown recluse spider you will notice localized symptoms that include mild stinging, redness and a bluish purple area around the bite with a ring of white surrounding it and a ring of red surrounding that, forming a bulls eye pattern. A blister filled with fluid begins to form within 8 hours of being bitten and when removed, it looks like a black ulcer. Additionally, both type of spider bites come with generalized symptoms that include nausea, vomiting, abdominal pain, stiffness or pain in the joints, a rash, extreme muscle cramps and a fever that is accompanied by a headache. When any of these symptoms are experienced along with what you suspect is a spider bite you will be able to see where you were bitten you should immediately seek medical attention to treat the bites and prevent them from becoming more serious.