Black Widow
When a black widow strikes, you may not even realize you've been bitten. When you do feel something, it feels like a pin-prick, according to the Mayo Clinic. First symptoms include mild swelling and red marks. Several hours later, the bitten area will hurt intensely and begin to stiffen. This is accompanied by chills, fever, queasiness, vomiting and severe abdominal pain, according to the Mayo Clinic. These bites are serious but rarely fatal.
Brown Recluse
A brown recluse bite feels like a mild sting, according to the Mayo Clinic. Within eight hours, the bitten area will turn red and become severely painful. Brown recluse bites also produce a fluid-filled blister, which subsides and then forms a deep ulcer. Brown recluse bites may also cause fever, rash, nausea and fatigue. Brown recluse bites can kill, more often in children than in adults.
Allergic Bites
Many spider bites carry no actual venom, but they can produce severe allergic reactions. Depending on a person's disposition to allergies, spider bites may cause a life-threatening reaction called anaphylaxis. Its symptoms set in within minutes or seconds, and they include abdominal pain, wheezing, diarrhea, trouble breathing, light-headedness, hives, nausea, vomiting, heavy heartbeat, redness and slurred speech.