In the United States, the brown recluse ( Figure 1) and the black widow ( Figure 2) are the 2 best-known species that can cause serious illness.īrown recluse spider. The bites of only a few spider species produce medically significant effects in humans.

Systemic effects, if they occur, are typically mild. Typically, the bite causes limited local tissue inflammation similar to the bites and stings of other small arthropods, and patients respond well to over-the-counter analgesics and antihistamines, if any treatment is needed. In most cases, the medical consequences of a spider bite are minor. Thus, a spider bite must be considered an anomaly that probably resulted from human actions which induced the arthropod to bite in self-defense. Unlike insects that feed on human blood or serum, spiders have no reason to bite humans. SPIDER BITES: AN OVERVIEW Spiders have complex and specialized feeding strategies they often use webs to capture and eat insects and other small arthropods. We also examine the reasons why the diagnosis of 'spider bite' remains a popular explanation for any unexplained dermonecrotic lesion, and we review the conditions in the differential diagnosis of such lesions. Here we describe the clinical features of spider bites and summarize the treatment options. Thus, we suggest that you approach the complaint of a 'spider bite' with a skeptical eye. Most of the conditions in the differential are far more common than spider bites. The spider is seldom seen by the patient, let alone recovered for identification, and the bite is often not felt.Īlthough spider bites can produce dermonecrotic wounds, the differential diagnosis of such lesions is extensive. This self-diagnosis is rarely corroborated by evidence, however. Patients often attribute the otherwise unexplained development of a dermonecrotic lesion to a spider bite.

Blood disorders and spider bits