Mild to severe pain usually develops 2-8 hours after the initial bite. Within 3-4 days necrosis develops and a dark eschar develops which gradually hardens. By the 7-14 day the wound edges become uneven and the center of the wound sinks and the eschar sloughs, leaving a painful ulcer. Third category consists of systemic loxoscelism. This may occur as early as 24-72 hours after the bite.
Children are especially vulnerable.
Symptoms are directly proportional to the amount of envenomation. The most common cause of death is massive hemolysis. The diagnosis of a BR spider is often difficult and delayed. There is no specific laboratory test or serological assay to identify a BR spider envenomation. If the diagnosis is suspected in a child, it is important to check a CBC every third day to rule out hemolysis.