What's a Black Widow Spider?

The black widow spider is one of a few poisonous kinds of spiders in the United States. It is part of the arachnid family, which includes not just spiders, but ticks, mites, and scorpions, too. Its body is about one-half inch long (smaller than a dime), and it has long legs. The black widow spider is shiny and black with a red-orange or yellow mark in the shape of an hourglass on its stomach.

Black widow spiders and their relatives can be found almost anywhere in the Western hemisphere of the world in damp and dark places. Their favorite places are woodpiles, tree stumps, trash piles, storage sheds, fruit and vegetable gardens, in stone walls, and under rocks.

If they come inside, they will go to dark places like corners of closets, garages, or behind furniture. They are shy by nature and bite only when trapped, sat on, or accidentally touched.

What a Bite Looks and Feels Like

A person who gets bitten by a black widow spider might not know it right away, since the bite can sometimes feel like a little pinprick. After 30 to 40 minutes, though, the area of the bite will swell and hurt a lot, and sometimes a person can get achy all over.

Other symptoms can include weakness, nausea, vomiting, sweating, and headache.

What You Should Do

If you ever think that you've been bitten by a black widow spider, tell an adult immediately. Black widow spider bites rarely kill people, but it's important to get medical attention as soon as you can because they can make you very sick.

With an adult's help, wash the bite well with soap and water. Then apply an ice pack to the bite, and try to elevate the area and keep it still to help prevent the spread of venom (poison).

If it's possible, have an adult catch and bring the spider to the doctor's office with you. Even though it's usually easy to identify black widows, you'll want to make sure that's the kind of spider that bit you. The spider can be killed first before you bring it with you; just be sure not to squish it so much that no one can tell what it is.

What a Doctor Will Do

Doctors treat people who have been bitten by black widow spiders with medications to help relax the muscles and reduce pain. They sometimes give antivenin, a medication that fights the venom in the spider's bite, if someone who has been bitten has underlying medical problems or doesn't get better from the other medications.

How to Avoid Getting Bitten

The best way to avoid getting bitten by black widow spiders is to be careful in areas where they like to spend time. Don't play around in rock piles or woodpiles. If you are working outside in the yard in big piles of logs or leaves, wear gloves.

Be sure to shake out blankets and clothing that have been stored in the attic or the basement, or if they have been in a closet but not used for a long time.

If you are cleaning behind furniture, look carefully behind it before reaching around. If you keep your shoes in a mudroom or garage, shake them out before putting them on.

Reviewed by: Elana Pearl Ben-Joseph, MD
Date reviewed: April 2013