About Spider Bites

For most of us, spider bites are not much of a threat. Of the more than 100,000 species of arachnids (which include spiders, scorpions, ticks, and mites), most are harmless. In spite of their horrific reputation, spiders are reclusive and unlikely to sit down beside us. But a few species bite, and in rare cases the bite, if untreated, can be serious or even fatal.

Signs of a Spider Bite

Reactions to a spider bite usually peak within two to three hours, then begin to subside. They can include muscle pain and swelling around the bite site; itching and/or burning; sweating, nausea, vomiting; and severe headache.

Types of Spider Bites

Two kinds of spiders were responsible for almost half of the spider bites reported to poison-control centers in the United States in the mid-1990s (the most recent period for which the Centers for Disease Control and Prevention has national figures): the black widow and the brown recluse.

The female black widow is about half an inch long with a shiny black body and a red hourglass-shaped mark on its underside. The brown recluse is smaller and has a violin-shaped mark on its upper body. Both types tend to dwell in dry, dark surroundings such as under porches or in woodpiles.

Another troublesome arachnid, the hobo spider, common in the Pacific Northwest, is thought to have inflicted many of the 5,300 other bites classified as “other/unknown,” and possibly some of those blamed on the brown recluse. Indeed, spider bites are more often reported in the Pacific Northwest (Oregon, Washington, Idaho) than in any other areas.

Tarantulas, a kind of large, hairy spider found mostly in the Southwest, racked up 82 bites. Some 15,000 insect bites are reported annually—but most people don’t know what kind of insect or spider bit them. If a spider bites you and you kill it, it may help if you take the spider along with you to a physician.

Immediate Care for Spider Bites

Most spider bites don’t require medical attention, but it’s important not to break the skin or lance the bite, which can lead to a secondary infection. For milder bites, which should heal in a day or two, cold compresses on the bite are helpful.

When to Seek Medical Attention for a Spider Bite

If a bite causes a severe reaction—which can include symptoms such as intense pain, muscle spasms, fever, chills, difficulty breathing, and/or convulsions—try to get medical help right away.

Also seek medical help for children under three or adults older than 70. This is especially important if the bite is from a black widow or brown recluse; bites from these spiders can be fatal for children or the elderly without treatment.

If a bite seems to be getting worse, it’s a good idea to seek medical attention. For a serious bite, you may need a tetanus shot and wound care. Antivenins (antivenom drugs) are available for black widow bites, but because of concern about adverse reactions, they are used only for severe cases.

Prevention Tips for Spider Bites

Protecting yourself from bites is the best policy. If you’re working in a crawl space, working outdoors where brush is piled up, or gathering wood for a campfire, it’s always a good idea to wear gloves and other protective clothing. If you have to use an outdoor privy, look before you sit.

Inspect your shoes before putting them on when you’re out camping—or if you’re putting on boots or shoes that you haven’t worn in some time.

For More Information about Spider Bites

  • Centers for Disease Control and Prevention

Publication Review By: the Editorial Staff at HealthCommunities.com

Published: 12 Aug 2010

Last Modified: 21 Oct 2014