Spider Bites: What You Should Know

Unless you see a spider bite you, don’t assume that mysterious bump on your skin came from an eight-legged creature. Spider bites are fairly rare.

These eight-legged creatures do bite people on occasion. But most of the time, these bites don’t cause a problem. That’s because most of the spiders in the U.S. have fangs that are too short to break your skin, and their venom isn’t strong enough to endanger a creature as large as a human.

Only two spiders that are native to the U.S. can do real harm when they bite a person: Black widows and brown recluses. Black widows tend to live in woodpiles, along fences or in outhouses in the South and West. Brown recluses tend to live in garages, attics or piles of rocks or firewood in the Midwest or South.

Both of these spiders tend to keep to themselves. They don’t bite unless they’re cornered. People sometimes invade their spaces without knowing it. That’s when they get bitten.

Symptoms of Spider Bites

Most look like normal bug bites, with red raised bumps that might itch. Bites from black widows or brown recluses may or may not look different. (In fact, bites from brown recluses may look and feel like nothing at all at first.) But if you’re bitten by either of these spiders, you’ll have symptoms that let you know right away that something’s wrong. These might include:

  • Sharp pain or swelling at the site of the bite
  • Pain that spreads to the back, belly or chest
  • Sweating
  • Severe stomach cramps or pain (most common with black widow bites)
  • Fever
  • Chills
  • Feeling achy all over
  • Joint pain
  • Weakness
  • Nausea
  • Headache
  • A deep ulcer that forms at the site of the bite, with the skin at the center turning purple (can occur from brown recluse bites)

Diagnosis

Your doctor will ask about your symptoms and how you were bitten. He’ll want to know if you saw a spider bite you, and if you did, what the spider looked like. That’s really the only way he can know for sure that it was a spider that bit you.

If you have more than one bite on different parts of your body, or if several people in your house were also bitten, a spider is probably not to blame. In this case, your doctor will examine you to rule out other causes, like infection or vasculitis (a condition that causes blood vessels to swell).

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Treatment

Many people who are bitten by spiders don’t need to visit the doctor, even if they’ve been bitten by a black widow or brown recluse. If you don’t have more severe symptoms like the ones listed above, you may be able to care for your spider bite at home. Try these tips so ease your pain or discomfort:

  • Clean the wound with soap and water.
  • Dab it with antibiotic cream.
  • Elevate (raise) the area that was bitten to reduce swelling.
  • Put an ice pack on the bite.
  • Take over-the-counter pain medicine, if needed.
  • Watch for more severe symptoms.

See a doctor right away if you were bitten by a black widow and y have extreme pain or other serious symptoms. He may need to give you an antivenom shot.

If the site of bite gets infected, you may need antibiotics. You might also need to get a tetanus booster. That’s because tetanus spores sometimes collect inside spider bites.

Prevention

You can try to avoid spider bites by doing your best to not cross paths with spiders.

For example, if you spend time working outside in places where spiders may live:

  • Wear long-sleeved shirts, hats and gloves.
  • Tuck your pants into your socks.
  • Shake out garden gloves and other clothing before putting them on.
  • Store gardening clothes in a tightly sealed plastic bag.
  • Move piles of firewood and stones away from your home, and use caution around them.

To prevent spider bites while indoors, try to avoid storing items in cool, dark spaces, like under the bed. And make sure that all windows and doors have screens. It’ll help to keep the bugs out.

WebMD Medical Reference Reviewed by Jennifer Robinson, MD on December 12, 2018

Sources

SOURCES:

Mayo Clinic: “Spider bites -- Overview,” Spider bites -- Symptoms and Causes,” “Spider bites -- Treatment,” “Spider bites -- Diagnosis,” “Spider bites -- Prevention.”

CDC: “Types of Venomous Spiders,” “Venomous Spider Recommendations.”

Nemours Foundation: “Bug Bites and Stings.”

U.S. Department of Labor: “Brown Recluse Spider.”

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