How do brown recluse spider bites present?

Unlike the black widow, the brown recluse produces a dermonecrotic toxin that can cause severe necrosis of the skin as well as a hemolytic toxin that causes severe, even life-threatening, hemolysis. The brown recluse is a shy, reclusive, brown spider with a dark brown violin-like marking on the dorsum of the cephalothorax, hence the name fiddleback spider. The spider is located largely in the Midwest but has been reported along the East Coast, in Texas, and in California. The bite commonly occurs when a person is cleaning old storage rooms or woodpiles outdoors, where the spider resides. Often, the spider is not seen or recovered at the time of the bite. The initial bite may be painless but is usually sharp and stinging for 6 to 8 hours and then is replaced by dull, aching pain that gradually increases in intensity and is accompanied by itching. The bite then begins to show a central blue color (impending necrosis), a surrounding white area (a vasospasm and ischemia), and a peripheral red halo (inflammation). Extension of this reaction demonstrates a remarkable gravitational spread to dependent areas. Over the next 2 to 4 days, the extent of the necrosis will be known. If a larger area of necrosis develops after a few days, a rare but serious and life-threatening systemic reaction to the hemolytic toxin may occur. Therefore, observation for hematologic changes such as red blood cell hemolysis or disseminated intravascular coagulopathy (DIC) should be observed.