What is a black widow spider?
The black widow spider is an eight-legged arachnid with a shiny black body that ranges from 1/4 inch to 1 3/8 inches long. Female black widows have a distinctive red hourglass-shaped marking on the underside of their bodies. Females are larger and more dangerous than males. Black widows get their name from the myth that the females eat the males after mating, leaving them “widowed,” but this rarely happens.
Where do black widow spiders live?
Black widow spiders mostly live in warm, dry climates in the Southern and Western U.S., but they can be found in all states except Hawaii and Alaska.
Black widows primarily live outdoors, where they build webs near garages, fences, woodpiles, building overhangs and other outdoor structures. They like to hide out in gardening equipment, outdoor furniture and garbage, as well. You may also find them in cluttered areas such as basements, closets, attics and under sinks.
How common are black widow spider bites?
Black widow spiders are a member of the Latrodectus family. People report about 2,600 Latrodectus-species bites to the National Poison Data System every year.
Symptoms and Causes
What are the symptoms of a black widow spider bite?
Black widow spiders have large fangs and glands that produce very toxic venom. When bitten, the venom attacks the nerve endings in your muscles, causing symptoms such as severe, bodywide muscle pain and cramping. However, only the female black widow bites. The males are too small and can’t break through human skin. Black widow spider bites typically occur when humans come into direct contact with their webs. They only bite when threatened.
A black widow spider bite causes a sharp, pinprick-like pain. A dull numbness in the bite area may follow. Black widow spider venom interferes with chemicals in your nerve endings. This can produce severe pain, stiffness and muscle spasms throughout your body, including your belly (abdomen), shoulders, chest and back.
Other black widow spider bite symptoms may include:
- Trouble breathing (dyspnea).
- Swollen or droopy eyes.
- Headache.
- Increased saliva production.
- Nausea and vomiting.
- Excessive sweating (diaphoresis).
- Fever and chills.
What does a black widow spider bite look like?
You may see tiny red fang marks where the spider bit you. You may also have mild redness and swelling in the bite area. A blister may form, or you may have an itchy skin rash. In addition, your skin may turn bluish-gray (cyanosis) at the bite site.
What causes a black widow spider to bite?
Male black widow spiders rarely bite. They’re too small and not able to break your skin with their fangs. But female black widows may bite in defense, especially after they lay eggs. Most spider bites are accidents. If you accidentally brush up against a spider, it’s just trying to defend itself. They don’t purposely try to attack you.
What are the complications of a black widow spider bite?
You can get a skin condition called cellulitis from a spider bite. Cellulitis occurs when bacteria enter your skin and cause an infection.
Rarely, some people have long-term pain or muscle spasms after black widow spider bites.
Diagnosis and Tests
How is a black widow spider bite diagnosed?
Healthcare providers can’t identify a particular spider based on its bite mark. There are no tests to confirm what kind of spider bit you. If you have the spider, bring it with you for confirmation. However, most of the time, you won’t have the spider. Providers usually diagnose a spider bite based on your symptoms.
Management and Treatment
What should I do if a black widow bites me?
If you think a black widow spider bit you:
- Wash the area with soap and water.
- Apply an ice pack to help reduce pain and swelling and to delay the effects of the venom. (Wrap the ice in a thin cloth — don’t apply the ice directly to your skin because direct contact can cause tissue damage.)
- Elevate the wound site, if possible.
- Don’t attempt to remove the venom (sucking out the venom is a dangerous practice that’s just as likely to envenom the person trying to do it).
- In the U.S., call the National Capital Poison Control Center (1-800-222-1222), and seek medical care. If you live outside the U.S., call the agency or organization specific to where you live.
How is a black widow spider bite treated?
Treatment for a black widow spider bite may include:
- Muscle relaxers and sedatives, to help relieve muscle pain and spasms.
- Analgesics, to help reduce pain.
- Antivenom, to help reverse the effects of the venom, including bodywide muscle cramping.
Black widow bites are serious. Children younger than 16 and people older than 60 may need hospitalization to treat:
- Breathing issues.
- Heart problems.
- High blood pressure.
- Severe muscle pain and cramping.
Complications/side effects of the treatment
Some people are allergic to the antivenom providers use to treat spider bites. This is rare, but in these cases, anaphylaxis can occur.
Prevention
Can black widow spider bites be prevented?
You can reduce your risk of a black widow spider bite by minimizing the clutter in your basement, attic and/or garage. This can help eliminate their hiding spots. Other ways to prevent black widow spider bites include:
- Wearing gloves when moving items that have been in storage for a long time. Also, wear gloves when working in your garden, carrying wood or moving rocks.
- Wearing long pants and sleeves in wooded areas.
- Shaking out your shoes, gloves and hats before wearing them.
- Applying an EPA-approved insect repellant.
- Treating shoes and clothing with insecticide.
- Storing firewood outside at least 20 feet away from your house on a raised structure (like a platform or rack).
Outlook / Prognosis
What is the outlook (prognosis) for a black widow spider bite?
The prognosis for black widow bites is generally good. With prompt treatment, you should make a full recovery within 24 to 48 hours. Some people experience long-term pain or muscle spasms after black widow bites, but this is rare.
Living With
When should I go to the ER?
After treatment for a black widow spider bite, you should return to the emergency department if the following symptoms develop:
- Rash.
- Joint or muscle pain.
- Blood in your urine (hematuria).
- Swollen lymph nodes.
- Trouble breathing.
What questions should I ask my healthcare provider?
If you were bitten by a black widow spider, you may want to ask your healthcare provider the following questions:
- Is there a way to confirm it was a black widow?
- What’s the best treatment for a black widow spider bite?
- Am I at risk for complications?
- What signs of infection should I look out for?
- How can I prevent future black widow spider bites?
A note from Cleveland Clinic
Black widow spiders have a bad reputation. But like all spiders, they really don’t want to bite you. They only bite when they feel the need to defend themselves. To avoid a black widow spider’s wrath, clear the clutter in your garage, basement and attic. And wear gloves if you’re working in an area that may have spiders. You should seek immediate medical attention if a black widow spider bites you.
