Seniors  |  Toddler and Preschool  |  Adults  |  Summer  |  Spring  |  Autumn  |  Insects and spiders

Black Widow Spiders

The Bottom Line

Black widow spider bites can be dangerous but fatal bites are rare. Black widow spider bites often are painful right away. After a bad bite, severe pain and muscle cramps can start in a couple of hours. Pain and muscle cramps can be treated. Antivenin is available but is needed only rarely.

The Full Story

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. The poison specialist who answers your call will tell you what to do. If you need emergency care, the poison specialist will contact the emergency room staff with treatment advice.

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


For More Information

Safety tips for outdoor workers and others who may come into contact with spiders (National Institute for Occupational and Safety Health)

References

Quan D. North American poisonous bites and stings. Crit Care Clin. 2012;28:633–659.

Poisoned?

CALL 1-800-222-1222

Prevention Tips

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.

This Really Happened

A 12-year-old girl felt a prick on her arm after putting on her jacket. She quickly developed pain at the site as well as pain in her back. The parents described a spider that looked like a black widow. The child was taken to the emergency room within 45 minutes with back, stomach, and chest spasms. She was in severe pain with high blood pressure and a fast heart rate. It took several hours to initially control her pain and muscle spasms, using intravenous morphine, sedation, and antihistamines as well as oral muscle relaxants and steroids. The pain and spasms continued during the next couple of days. The child spent three days in the hospital.