Black Widow Spider Bites Can Be Dangerous

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Black widow spider bites can be dangerous, especially to young children and elderly people. Hospital treatment is sometimes needed, but fatal bites are rare. Some pest control operators report an increased number after mild winter seasons.

Black widow spiders are about the size of a half-dollar, including the legs. They appear hard, black, and shiny. The abdominal section is large and rounded. The classic marking is a red hourglass shape, but the marks can be orange or white or tan. Also, the markings might be dots or spots, instead of the typical hourglass shape. The webs look tangled and messy.

These spiders like dark, undisturbed areas. You might find them in stacks of wood, brush piles, corners of garages and sheds, under flowerpots, inside gardening gloves and boots, and other sheltered places. Black widow spiders won't come after you. But if they feel threatened, they will bite.

A black widow spider bite often is painful right away. There will be tiny puncture wounds at the bite site, with some local swelling. Wash the area well with soap and water. If there is no pain, or if the pain is mild, no special treatment is needed.

After a bad bite, severe pain and muscle cramps can start in a couple of hours. Muscle cramps start in the area of the bite (often a hand or foot) and move towards the center of the body. Some black widow bites cause such extreme pain that it's mistaken for appendicitis or a heart attack. This kind of intense pain is treated with narcotics. Muscle cramps are treated with muscle relaxants. Once in a while, black widow bites can cause trouble breathing. There is an antivenin for such serious cases, but it's rarely needed.

Anyone who is bitten needs protection from tetanus. If you haven't had a tetanus booster shot in the last five years, call your physician.

Because black widow spiders hide, you might not see them even if they're close by. Protect yourself in areas where they might live.

• Shake out your gardening gloves before putting them on. Shake out boots or shoes that you've stored in garages, basements, or sheds before putting them on.
• Always wear gloves when moving wood, reaching into wood piles, handling mulch, grabbing empty flower pots, etc.
• If you'll be working in a garage or shed, or under a porch or deck, wear a hat to protect your head.

If you have a lot of black widow spiders and are concerned, consider consulting a professional pest control applicator for advice. 

If someone is bitten by a black widow spider, call Poison Control right away at 1-800-222-1222 or use the webPOISONCONTROL^® online tool for guidance.

Rose Ann Gould Soloway, RN, BSN, MSEd, DABAT emerita
Clinical Toxicologist