Skip to content
Call a poison centerGet help online
Loading Theme Toggle

Black widow spider bites can be dangerous

Test Image

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.

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.

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, use the webPOISONCONTROL® online tool to get help, or call your poison center at 1-800-222-1222. Whether online or by phone, expert guidance is always free, confidential, and available 24 hours a day.

Related Articles

Back to blog
  • spotted lanternfly on tree

    Shining a light on spotted lanternflies

    The spotted lanternfly is an insect species native to parts of China and Vietnam. The insect itself does not bite or sting. It is not known to be toxic to humans but could cause upset stomach if ingested. Potential side effects of ingesting small amounts of spotted lanternflies are nausea, vomiting, constipation, abdominal pain, and loss of appetite. These symptoms are self-limited and do not typically require treatment.

    Find out more
  • pest strip

    Use pest strips as directed!

    Pest strips are typically made out of either glue on a paper backing or a porous strip impregnated with an organophosphate insecticide. Glue may stick to the skin or get in the eyes, but is unlikely to result in significant toxicity. However, exposure to organophosphates can be very toxic, causing muscle weakness, vomiting, diarrhea, seizures, and coma.

    Find out more
  • mosquito

    Use DEET safely

    DEET is an insect repellant which helps prevent bites, and illnesses, from mosquitos and ticks. There are rare reports of health problems associated with the use of DEET, but most have been because of using the product incorrectly. The potential risks of West Nile Virus, Lyme disease, and other diseases caused by infected insects surpass the slight risks associated with DEET.

    Find out more
  • tick habitat sign

    Treating tick bites

    Ticks are most active during warmer months (April-September), but tick bites can happen during any time of the year. Ticks live in grassy, wooded, brush-filled areas or even on animals. Tick exposure can happen in your own backyard. See a healthcare provider if you experience fever, rash, or aches within a few weeks of a tick bite.

    Find out more
  • mother applying tick repellent on son

    An introduction to common tick-borne diseases

    Ticks are experts at feeding on your blood and, in return for your generosity, transmitting disease to you. There are several different kinds of bacterial, viral, and parasitic diseases transmitted by ticks, and tick-borne diseases are on the rise. Prevention is key: do what you can to prevent them from having access to you.

    Find out more