Spider Bite

Skin | Emergency Medicine | Spider Bite (Symptom)


A primary concern of the bite of a spider is the effect of its venom. A spider envenomation occurs whenever a spider injects venom into the skin. Spider venoms work on one of two fundamental principles; they are either neurotoxic (attacking the nervous system) or necrotic (attacking tissues surrounding the bite, and, in some cases, attacking vital organs and systems).

Bites from all kinds of toxic bugs create local reactions associated with: redness, swelling, itching and pain. Assumption that a reported injury was caused by a spider is the most common source of false reports, which in some cases have led to misdiagnosis and mistreatment, with potentially life-threatening consequences.

Many spider bites, including those by some dangerous species, are relatively painless at first and may go unnoticed if not directly observed. Victims should be concerned when a local reaction continues to get worse for more than 24 hours.

Diagnosis and Treatment

Most spider bites are harmless, and require no specific treatment. Treatment of bites may depend on the type of spider; thus, capture of the spider—either alive, or in a well-preserved condition, is useful.

In the case of bites by widow spiders, Australian venomous funnel-web spiders, or Brazilian wandering spiders, prompt medical attention should be sought as in some cases the bites of these spiders may develop into a medical emergency.

Treatment for non-poisonous spider bites include washing the bite with soap and water and ice to reduce inflammation. . Analgesics and antihistamines may be used, however antibiotics are not recommended unless there is also a bacterial infection present.