Black Widow Spider Bite

Medically Reviewed by Jabeen Begum, MD on May 11, 2023
3 min read

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 belly (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. They only bite when disturbed.

The black widow spider makes a venom that affects your nervous system. Some people are slightly affected by it, but others may have a serious response. You may feel serious pain, burning, swelling, and redness at the site. You may even see two fang marks.

Other symptoms include:

If you have serious symptoms like these, seek medical help right away.


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, call your doctor or a poison control center right away. 

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

In the meantime, you can 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 acetaminophen.
  • 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, capture and kill the spider (place it in a plastic bag or jar) and take it to your doctor visit. This way, they’ll know for sure whether it was a black widow that bit you.

the doctor will review your symptoms and decide what treatment, if any, you need. If your symptoms are serious, you may need muscle relaxants or stronger pain medicine. You might have to stay in the hospital, though that’s rarely the case.

In the most serious cases, the 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 they've 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, they’ll have to monitor you for about 8-12 days afterward.

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.