Spider Bites

DEFINITION

Spider bites are usually harmless. In fact, many bites attributed to spiders turn out to have been inflicted by other bugs. Skin infections also have been mistaken for spider bites.

Only a few types of spiders have fangs long enough to penetrate human skin and venom strong enough to severely affect a human being. In the U.S., these include the black widow spider and the brown recluse spider.

Black widow spider bites can cause severe abdominal pain and cramping, while brown recluse spider bites can cause the skin around the bite to die. Both these spiders generally live in undisturbed areas, such as attics or sheds, and don’t bite unless threatened.

CAUSES

Severe spider bite symptoms occur as a result of injected spider venom. The severity of symptoms depends on the type of spider, the amount of venom injected and how sensitive your body is to the venom.

SYMPTOMS

Typically, a spider bite looks like any other bug bite — a red, inflamed, sometimes itchy or painful bump on your skin — and may even go unnoticed. Harmless spider bites usually don’t produce other symptoms.

Black widow spider bites

Signs and symptoms of a black widow spider bite may include:

• Pain. Typically beginning within an hour of being bitten, pain can spread from the bite site into your abdomen, back or chest.
• Cramping. Abdominal cramping or rigidity can be so severe that it’s sometimes mistaken for appendicitis or a ruptured appendix.
• Sweating. Excessive sweating can occur around the bite mark or may involve the entire limb.

Brown recluse spider bite

The pain associated with a brown recluse spider bite typically increases during the first eight hours after the bite. The bite usually heals on its own in about a week. In a minority of cases, the skin at the center of the bite can become dusky red and then evolve into a deep open sore (ulcer) that enlarges as the surrounding skin dies. The ulcer usually stops growing within 10 days after the bite, but full healing can take months.

When to see a doctor

Seek prompt medical assistance if you believe you’ve been bitten by a spider and you’re experiencing:

• Severe pain
• Abdominal cramping
• A growing ulcer at the bite site