Diagnosis

Spider bites can be mistaken for other skin sores that are red, painful or swollen. Many skin sores attributed to spider bites turn out to have been caused by bites from other bugs, such as ants, fleas, mites, mosquitoes and biting flies. Skin infections and other skin conditions, even burns, can be mistaken for spider bites.

Your doctor will likely diagnose a spider bite based on your history and your signs and symptoms. The process might involve determining whether anyone saw a spider bite you, having an expert identify the spider, and ruling out other possible causes of the signs and symptoms.

Black widow identification

Some clues for identifying black widow spiders include:

• Shiny black body with long legs
• Red hourglass shape on the belly
• Length of entire body, including legs, about 1 inch (2.5 cm) across

Brown recluse identification

Some clues for identifying brown recluse spiders include:

• Golden or dark brown body with long legs
• Dark violin shape on top of the leg attachment segment
• Six eyes — a pair in front and a pair on both sides — rather than the usual spider pattern of eight eyes in two rows of four
• Central body is about 1/2 inch (1.2 cm) across