Black Widow Spider Bite

The black widow is a medium-sized spider -- about a half-inch long. Two species are common to the United States:

  • The southern black widow. This spider has a shiny, black, globe-shaped abdomen. You’ll know it by the red hourglass mark on the underside.
  • The northern black widow. You’ll notice a row of red spots down the middle of the upper surface of its abdomen. It also has two crosswise bars on the underside. Just to make things interesting, the markings can also be yellow or white. The spider may be brown or have red legs.

These spiders are active at night. They prefer dark corners or crevices, like garages. Only the females bite humans, and only when they’re disturbed.

Symptoms

The black widow spider produces a protein venom (poison) that affects your nervous system. Some people are slightly affected by it, but others may have a severe response. Right away, you may feel severe pain, burning, swelling, and redness at the site. You may even see two fang marks.

Other symptoms include:

Many of the symptoms of a black widow bite can look like those of other conditions. But if you think you’ve been bitten by this spider, make an appointment to see your doctor.

IMPORTANT: If you suspect your child was bitten by a black widow, get to the emergency room right away. These bites can be fatal in young children.

In the meantime, try these tips to ease your symptoms and prevent further infection:

  • Wash the area with soap and water.
  • Apply a cold washcloth or ice pack wrapped in cloth to the area.
  • Take an over-the-counter pain reliever, like Tylenol.
  • If the bite is on your arm or leg, elevate it to prevent swelling.
  • Apply an antibiotic cream or lotion to the bite.

If possible, kill and capture the spider (place it in a plastic bag or jar) and take it to your doctor appointment. This way, he’ll know for sure that it was a black widow that bit you.

Continued

Your doctor will review your symptoms and decide what more treatment, if any, is needed. If they’re severe, you may need muscle relaxants or stronger pain medicine. You may have to stay in the hospital, though that’s rarely the case.

In the most severe cases, your doctor may inject you with antivenin. It’s a drug made from substances in the blood of horses. Antivenin neutralizes the black widow’s venom. That means it prevents it from causing you harm.

Your doctor will only use this treatment after he’s spoken with another doctor who has experience in treating these bites. Antivenin can cause a number of side effects, so if your doctor gives it to you, he’ll have to monitor you for about 8 to 12 days afterward.

Prevention

Black widow spiders live in cool, dark places like sheds and garages. They normally bite when they’re startled or surprised. To reduce your risk of being bitten, keep storage areas clean. And outside, try to avoid woodpiles, fallen tree branches, and other places they may hide.

WebMD Medical Reference Reviewed by Neha Pathak, MD on January 03, 2017

Sources

SOURCES:

Mayo Clinic: “Spider Bites: First Aid.”

KidsHealth.org: “First Aid: Spider Bites.”

Munson Healthcare Cadillac Hospital: “Spider Bites.”

Johns Hopkins Medicine: “Spider Bites.”

Stanford Children’s Health: “Spider Bites in Children.”

Merck & Co.: “Antivenin.”

© 2017 WebMD, LLC. All rights reserved.

Pagination