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Poisoning Due to Black Widow Spider Venom (Black Widow Spider Bites)

Black Widow Spiders

Black widow spiders are easily recognizable. They’re plump, black, and shiny, with an hourglass-shaped, red mark on their abdomens. Sometimes, this red mark may take a slightly different shape. In other cases, the spider may have red markings on its back too.

This type of spider gets its name from its mating behavior. After mating, the females typically kill and then eat their male partners, leaving them as "widows."

These spiders aren’t aggressive and only bite when they feel threatened. The bites usually aren’t fatal, but they can still cause some serious and uncomfortable symptoms.

If a black widow spider has bitten you, get medical treatment right away.

This spider type is found throughout the world. While they are found all over the United States, they’re most common in the Southern and Western states.

What Are the Symptoms of Black Widow Spider Venom Poisoning?

You’ll usually feel the sensation of a minor pinprick when a black widow spider first bites you. You might not realize that you’ve been bitten at first unless you caught the spider in the act. In some cases, the bite might be painful right away.

The area around the bite will likely redden and begin to swell.

You’ll develop more serious symptoms within a few hours of the bite. Sometimes, the more serious symptoms can develop in as little as 15 minutes after the bite occurs. Most commonly, you’ll experience pain that’s not limited to the bite location. Your chest and abdomen, in particular, will be painful. The muscles in these areas will cramp and go rigid due to severe muscle spasms. Your back and shoulders may also hurt.

Other signs and symptoms you might experience include:

In rare and extreme cases, black widow spider venom poisoning may lead to seizures and even death. Death generally doesn’t occur in healthy adults. Young people, the elderly, and those with weakened immune systems are more susceptible to serious complications and death from a black widow spider bite.

Regardless, anyone who has been bitten, or who suspects they’ve been bitten by a black widow spider, should seek medical treatment immediately.

What Causes a Black Widow Spider to Bite?

Black widow spiders are reclusive and not aggressive. They’ll never seek you out to bite you. Instead, they only bite in self-defense or when they feel threatened.

Black widow spiders live in dark, hidden spots, such as in piles of rocks, leaves, or wood. Don’t move or disturb these piles without wearing gloves, as you might accidentally touch a black widow spider and get bitten.

You should also wear gloves when you’re moving things out of dark corners in garages or basements. Black widow spiders may live in these areas.

These spiders might also hide in a variety of other dark places, such as:

  • inside your shoes, especially if they’re stored somewhere dark
  • in piles of unused blankets
  • in the crevices of porch furniture
  • between stones in a rock wall

How Is Black Widow Spider Venom Poisoning Treated?

Treatment for a black widow bite will vary depending on your health, symptoms, and the severity of the bite.

You may be given medication to help ease your pain. You might also be given medications to help lower the high blood pressure that sometimes accompanies a black widow spider bite.

If the bite is more severe, you may need muscle relaxants or antivenin, which is an antitoxin used to treat venomous bite). In some cases, you may even need to be hospitalized.

You should go to a doctor or emergency room right away if a black widow spider has bitten you.

There are some steps you can take immediately preceding your trip to the hospital or on the way to the hospital.

  • Wash the bite thoroughly with soap.
  • Apply a wet or damp ice pack for 10 minutes at a time, with 10-minute breaks in between.
  • Elevate the location of the bite, if possible. For example, if you were bitten on your hand, keep your arm over your head. You should get to a hospital as soon as possible.

Content licensed from:

Written by: Gretchen Holm
Medically reviewed on: Jan 29, 2016: Steve Kim, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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